When serum bilirubin concentration is high, about 43 mol/l or more, jaundice appears. Some cases of jaundice such as hemolytic jaundice, neonatal jaundice, obstructive jaundice (gallstones, pancreatic head cancer, etc.)
Enzyme alterations in hyperbilirubinemia
Reason
Fecal bilirubin | Urine bilirubin | Direct bilirubin next(%total) | ASAT | ALAT | Alkaline phosphatase | |
Hemolysis | | - | < 20 | Jar often | Jar often | Normal |
Cell destruction liver (viral or toxic) | | + | > 40 | | | |
Jaundice or cholestasis | | + | > 50 | | | |
Alcoholic cirrhosis | Jar often | | < 30 | | | |
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Presents the Definition, Classification, and Composition of Drug Emulsions. -
Presenting the Definition, Classification, and Composition of Drug Suspensions. -
![Qos Assurance Methods for Multimedia Communications
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low. The EF PHB requires a sufficiently large number of output ports to provide low delay, low loss, and low jitter.
EF PHBs can be implemented if the output ports bandwidth is sufficiently large, combined with small buffer sizes and other network resources dedicated to EF packets, to allow the routers service rate for EF packets on an output port to exceed the arrival rate λ of packets at that port.
This means that packets with PHB EF are considered with a pre-allocated amount of output bandwidth and a priority that ensures minimum loss, minimum delay and minimum jitter before being put into operation.
PHB EF is suitable for channel simulation, leased line simulation, and real-time services such as voice, video without compromising on high loss, delay and jitter values.
Figure 2.10 Example of EF installation
Figure 2.10 shows an example of an EF PHB implementation. This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ.
Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally
not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets.
2.2.4.2 Assured Forwarding (AF) PHB
PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels.
Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance.
PHB Class
PHB Subclass
Package type
DSCP
AF4
AF41
Short
100010
AF42
Medium
100100
AF43
High
100110
AF3
AF31
Short
011010
AF32
Medium
011100
AF33
High
011110
AF2
AF21
Short
010010
AF22
Medium
010100
AF23
High
010110
AF1
AF11
Short
001010
AF12
Medium
001100
AF13
High
001110
Table 2.8 AF DSCPs
The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped.
When service levels are defined using AF classes, different quantity and quality between AF classes can be realized by allocating different amounts of bandwidth and buffer space to the four AF classes. Unlike
EF, most AF traffic is non-real-time traffic using TCP, and the RED queue management strategy is an AQM (Adaptive Queue Management) strategy suitable for use in AF PHBs. The four AF PHB layers can be implemented as four separate queues. The output port bandwidth is divided into four AF queues. For each AF queue, packets are marked with three “colors” corresponding to three separate priority levels.
In addition to the 32 DSCP 1 groups defined in Table 2.8, 21 DSCPs have been standardized as follows: one for PHB EF, 12 for PHB AF, and 8 for CSCP. There are 11 DSCP 1 groups still available for other standards.
2.2.5.Example of Differentiated Services
We will look at an example of the Differentiated Service model and mechanism of operation. The architecture of Differentiated Service consists of two basic sets of functions:
Edge functions: include packet classification and traffic conditioning. At the inbound edge of the network, incoming packets are marked. In particular, the DS field in the packet header is set to a certain value. For example, in Figure 2.12, packets sent from H1 to H3 are marked at R1, while packets from H2 to H4 are marked at R2. The labels on the received packets identify the service class to which they belong. Different traffic classes receive different services in the core network. The RFC definition uses the term behavior aggregate rather than the term traffic class. After being marked, a packet can be forwarded immediately into the network, delayed for a period of time before being forwarded, or dropped. We will see that there are many factors that affect how a packet is marked, and whether it is forwarded immediately, delayed, or dropped.
Figure 2.12 DiffServ Example
Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on
Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a routers per-hop behavior is based only on the packets marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability.
Chapter Conclusion
Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of solving the disadvantages of the IntServ model.
DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy.
Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS
In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc.
In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being frozen, or many packets being dropped, seriously affecting service quality.
Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion.
3.1. DropTail method
DropTail is a simple, traditional queue management method based on FIFO mechanism. All incoming packets are placed in the queue, when the queue is full, the later packets are dropped.
Due to its simplicity and ease of implementation, DropTail has been used for many years on Internet router systems. However, this algorithm has the following disadvantages:
− Cannot avoid the phenomenon of “Lock out”: Occurs when 1 or several traffic streams monopolize the queue, making packets of other connections unable to pass through the router. This phenomenon greatly affects reliable transmission protocols such as TCP. According to the anti-congestion algorithm, when locked out, the TCP connection stream will reduce the window size and reduce the packet transmission speed exponentially.
− Can cause Global Synchronization: This is the result of a severe “Lock out” phenomenon. Some neighboring routers have their queues monopolized by a number of connections, causing a series of other TCP connections to be unable to pass through and simultaneously reducing the transmission speed. After those monopolized connections are temporarily suspended,
Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed.
− Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the routers buffer, this method is very expensive and ineffective.
− No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy.
The problem of choosing the buffer size of the routers in the network is to “absorb” short bursts of traffic without causing too much queuing delay. This is necessary in bursty data transmission. The queue size determines the size of the packet bursts (traffic spikes) that we want to be able to transmit without being dropped at the routers.
In IP-based application networks, packet dropping is an important mechanism for indirectly reporting congestion to end stations. A solution that prevents router queues from filling up while reducing the packet drop rate is called dynamic queue management.
3.2. Random elimination method – RED
3.2.1 Overview
RED (Random Early Detection of congestion; Random Early Drop) is one of the first AQM algorithms proposed in 1993 by Sally Floyd and Van Jacobson, two scientists at the Lawrence Berkeley Laboratory of the University of California, USA. Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet.
The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router.
Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the
traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways:
− Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes.
− Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet).
Figure 3. 1 RED algorithm
The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols.
To achieve the above goals, RED gateways must do the following:
− The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to.
− The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion
If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network.
− An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connections shared bandwidth at the gateway.
− Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows).
3.2.2 Algorithm
This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5]
For each packet arrival
Caculate the average queue size avg If minth ≤ avg < maxth
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Qos Assurance Methods for Multimedia Communications
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low. The EF PHB requires a sufficiently large number of output ports to provide low delay, low loss, and low jitter.
EF PHBs can be implemented if the output port's bandwidth is sufficiently large, combined with small buffer sizes and other network resources dedicated to EF packets, to allow the router's service rate for EF packets on an output port to exceed the arrival rate λ of packets at that port.
This means that packets with PHB EF are considered with a pre-allocated amount of output bandwidth and a priority that ensures minimum loss, minimum delay and minimum jitter before being put into operation.
PHB EF is suitable for channel simulation, leased line simulation, and real-time services such as voice, video without compromising on high loss, delay and jitter values.
Figure 2.10 Example of EF installation
Figure 2.10 shows an example of an EF PHB implementation. This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ.
Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally
not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets.
2.2.4.2 Assured Forwarding (AF) PHB
PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels.
Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance.
PHB Class
PHB Subclass
Package type
DSCP
AF4
AF41
Short
100010
AF42
Medium
100100
AF43
High
100110
AF3
AF31
Short
011010
AF32
Medium
011100
AF33
High
011110
AF2
AF21
Short
010010
AF22
Medium
010100
AF23
High
010110
AF1
AF11
Short
001010
AF12
Medium
001100
AF13
High
001110
Table 2.8 AF DSCPs
The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped.
When service levels are defined using AF classes, different quantity and quality between AF classes can be realized by allocating different amounts of bandwidth and buffer space to the four AF classes. Unlike
EF, most AF traffic is non-real-time traffic using TCP, and the RED queue management strategy is an AQM (Adaptive Queue Management) strategy suitable for use in AF PHBs. The four AF PHB layers can be implemented as four separate queues. The output port bandwidth is divided into four AF queues. For each AF queue, packets are marked with three “colors” corresponding to three separate priority levels.
In addition to the 32 DSCP 1 groups defined in Table 2.8, 21 DSCPs have been standardized as follows: one for PHB EF, 12 for PHB AF, and 8 for CSCP. There are 11 DSCP 1 groups still available for other standards.
2.2.5.Example of Differentiated Services
We will look at an example of the Differentiated Service model and mechanism of operation. The architecture of Differentiated Service consists of two basic sets of functions:
Edge functions: include packet classification and traffic conditioning. At the inbound edge of the network, incoming packets are marked. In particular, the DS field in the packet header is set to a certain value. For example, in Figure 2.12, packets sent from H1 to H3 are marked at R1, while packets from H2 to H4 are marked at R2. The labels on the received packets identify the service class to which they belong. Different traffic classes receive different services in the core network. The RFC definition uses the term behavior aggregate rather than the term traffic class. After being marked, a packet can be forwarded immediately into the network, delayed for a period of time before being forwarded, or dropped. We will see that there are many factors that affect how a packet is marked, and whether it is forwarded immediately, delayed, or dropped.
Figure 2.12 DiffServ Example
Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on
Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a router's per-hop behavior is based only on the packet's marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability.
Chapter Conclusion
Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of solving the disadvantages of the IntServ model.
DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy.
Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS
In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc.
In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being "frozen", or many packets being dropped, seriously affecting service quality.
Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion.
3.1. DropTail method
DropTail is a simple, traditional queue management method based on FIFO mechanism. All incoming packets are placed in the queue, when the queue is full, the later packets are dropped.
Due to its simplicity and ease of implementation, DropTail has been used for many years on Internet router systems. However, this algorithm has the following disadvantages:
− Cannot avoid the phenomenon of “Lock out”: Occurs when 1 or several traffic streams monopolize the queue, making packets of other connections unable to pass through the router. This phenomenon greatly affects reliable transmission protocols such as TCP. According to the anti-congestion algorithm, when locked out, the TCP connection stream will reduce the window size and reduce the packet transmission speed exponentially.
− Can cause Global Synchronization: This is the result of a severe “Lock out” phenomenon. Some neighboring routers have their queues monopolized by a number of connections, causing a series of other TCP connections to be unable to pass through and simultaneously reducing the transmission speed. After those monopolized connections are temporarily suspended,
Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed.
− Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the router's buffer, this method is very expensive and ineffective.
− No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy.
The problem of choosing the buffer size of the routers in the network is to “absorb” short bursts of traffic without causing too much queuing delay. This is necessary in bursty data transmission. The queue size determines the size of the packet bursts (traffic spikes) that we want to be able to transmit without being dropped at the routers.
In IP-based application networks, packet dropping is an important mechanism for indirectly reporting congestion to end stations. A solution that prevents router queues from filling up while reducing the packet drop rate is called dynamic queue management.
3.2. Random elimination method – RED
3.2.1 Overview
RED (Random Early Detection of congestion; Random Early Drop) is one of the first AQM algorithms proposed in 1993 by Sally Floyd and Van Jacobson, two scientists at the Lawrence Berkeley Laboratory of the University of California, USA. Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet.
The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router.
Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the
traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways:
− Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes.
− Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet).
Figure 3. 1 RED algorithm
The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols.
To achieve the above goals, RED gateways must do the following:
− The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to.
− The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion
If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network.
− An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connection's shared bandwidth at the gateway.
− Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows).
3.2.2 Algorithm
This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5]
For each packet arrival
Caculate the average queue size avg If minth ≤ avg < maxth
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Quality Management and Levels of Quality Management -
Solutions for Security and Travel Safety
3. SOME HEMATOLOGICAL TESTS
3.1. RED BLOOD CELLS
(1mm 3 in men has 4,200,000 ± 200,000; in women has 3,850,000 � 150,000 )
The main function of red blood cells is to transport oxygen from the lungs to the tissues thanks to the role of hemoglobin. Normal hemoglobin concentration in Vietnamese people is: male 14.6 0.6g/dl; female 13.2 0.5g/dl.
Anemia is when hemoglobin concentration is lower than 13g/dl in men and 12g/dl in women.
There are also cases of pseudocyesis due to blood dilution causing increased plasma volume.
Hematocrite (male: 39- 45%; female 35- 42%)
If anticoagulated whole blood is centrifuged in a capillary tube, two parts will be separated: plasma and blood cells. The comparison of the percentage between the volume of blood cells and whole blood is called hematocrite. Hematocrite decreases in hemolytic anemia and increases in dehydration due to diarrhea, vomiting, and prolonged fever.
Red blood cell index
These indices are used to classify anemia Mean corpuscular volume (MCV)
MCV = Hematocrite / Red blood cell count Mean corpuscular hemoglobin (MCH)
MCH = Hemoglobin / Red Blood Cell Count Mean corpuscular hemoglobin concentration (MCHC)
MCHC = Hemoglobin / Hematocrite MCHC = MCH / MCV
Normal value | Meaning | |
MCV | 88- 100 m 3 1fl (femtolite) = 10 -15 liters = 1 m 3 | Detect changes in red blood cell size: <80: microcytic >100: large red blood cells >160: giant red blood cells |
MCH | 28- 32pg (picogram) 1.8- 2fmol (femtomol) | |
MCHC | 320- 350g/l = 20- 22mmol/l | Determine the nature of isochromatic, hyperchromatic or hypochromatic of anemia |
Red blood cell index
The following are common anemia conditions:
Hypochromic anemia, small red blood cell size, hemoglobin is much lower than the number of red blood cells, seen in anemia due to chronic bleeding, stomach ulcers, hookworms, hemorrhoids, malaria, iron deficiency in diet.
Normochromic anemia, normal red blood cell size, hemoglobin decreases parallel to red blood cell count, seen in acute bleeding, some cases of hemolytic anemia, some infectious diseases, typhoid.
Hyperchromic anemia, large red blood cells, low hemoglobin compared to the number of red blood cells, seen in Biermer anemia, anemia after gastrectomy, pregnancy, cirrhosis, vitamin B12 or folic acid deficiency.
Reticulocytes (0.5- 1.5% of RBCs; SI = 0.005- 0.015)
These are young red blood cells that have just been released into the blood. After 24-48 hours, these red blood cells become normal red blood cells. After bleeding or hemolysis, this rate can be up to 30-40%.
Erythrocyte sedimentation rate (3-7mm/hour in men; 5-10mm/hour in women)
The erythrocyte sedimentation rate is the sedimentation rate of red blood cells in anticoagulated blood drawn into a capillary tube of a certain diameter in an upright position.
Plasma column height is usually obtained after the first 1 or 2 hours.
Erythrocyte sedimentation rate increases in inflammatory diseases such as rheumatism, progressive tuberculosis, cancer...
3.2. LEUKOCYTE (3200- 9800/mm 3 )
White blood cells help the body fight pathogens through phagocytosis or immunity. Based on shape and structure, white blood cells are divided into 5 types with the following ratio:
Neutrophils 50-70%
Basophils 0-1%
Acidophilic granulocytes 1- 4%
Lymphocytes 20-25%
Monocytes 5-7%
White blood cell count above 10,000/mm 3 is called leukocytosis, below 3,000/mm 3 is considered leukopenia .
Neutrophils (1,100- 7,000 /mm 3 )
Has a phagocytic role.
Neutropenia is found in acute infections such as pneumonia, appendicitis, pus-causing diseases, boils, etc.
Neutropenia can be due to decreased reproduction or increased destruction seen in infections such as typhoid, influenza, measles, HIV, malaria or due to some
Drugs that affect DNA synthesis such as phenothiazines, phenytoin, antibiotics, sulfonamides, anticancer drugs...
A severe condition is agranulocytosis, which is manifested by a sudden, very severe decrease in granulocytes (<200/mm3 ) accompanied by fever, ulcers, and necrosis of the oral and pharyngeal mucosa... Agranulocytosis occurs in cases where the bone marrow is severely damaged by infection, poisoning...
Eosinophils (eosinophils = 0 - 400/ mm 3 )
Has the ability to act as a macrophage but is weaker than a neutrophil. Increased in allergies, asthma, eczema, worms, parasites...
Decreased in shock, Cushing's disease, and states of complete bone marrow failure.
Basophils (0 - 150/ mm 3 )
Very rare in blood, they are incapable of motility and phagocytosis.
They also play a role in allergies.
Basophils increase in hypersensitivity states, hypothyroidism and decrease in corticosteroid treatment.
Monocytes (200 - 700/mm3)
After being produced in the bone marrow, monocytes enter the blood for a short time and then enter the tissues, becoming macrophages. A macrophage can engulf up to 100 bacterial cells, eat old red blood cells, dead neutrophils, parasites, necrotic tissue... In addition, they also play a role in initiating the immune process.
Monocytes increase in acute and chronic infections such as tuberculosis, influenza, typhoid, fungus, hepatitis, cancer...
Lymphocytes (1,500 - 3,000/mm3)
Are immune cells, localized in the spleen and lymphoid tissues.
There are 2 types:
B lymphocytes have humoral immune function.
T lymphocytes have cellular immune functions.
Lymphocyte proliferation and deregulation also change in some viral and bacterial infections.
When the number of lymphocytes decreases significantly, the patient suffers from immunodeficiency. Immunodeficiency can be congenital or acquired (due to chemicals used in cancer, immune substances used in tissue transplantation, radiation, HIV infection, etc.).
3.3. PLATELETS (150,000- 300,000/mm3)
These are non-nucleated cells that participate in the process of hemostasis. Thrombocytopenia below 100,000/mm3 can easily cause bleeding. Thrombocytopenia can be caused by bone marrow failure, cancer, arsenic poisoning, benzene poisoning, bacterial and viral infections.
Many drugs can cause thrombocytopenia such as chloramphenicol, quinidine, heparin, anticancer drugs... Many drugs have the ability to inhibit platelet adhesion such as Aspirin.
EVALUATION QUESTION
1) Name 7 blood biochemical test indicators that help diagnose and monitor disease progression and monitor drug effects.
2) Characteristics of plasma creatinine
3) Meaning of plasma creatinine test
4) Relationship between clearance coefficient and plasma creatinine content
5) Characteristics of urea in blood
6) Meaning of blood urea test
7) Characteristics of plasma glucose
8) Significance of plasma glucose testing
9) Characteristics of uric acid in the blood
10) The significance of blood uric acid testing
11) Characteristics of serum proteins
12) Significance of serum protein testing
13) Characteristics of creatine kinase (CK) or creatine phosphokinase (CPK)
14) The significance of testing creatinine kinase or Creatin phosphokinase CPK)
15) Characteristics of aspartate amino transferase
16) Significance of aspartate amino transferase (ASAT) test
17) Characteristics of alanine amino transferase (ALAT)
18) Significance of alanine amino transferase (ALAT) test
19) Characteristics of bilirubin
20) Significance of bilirubin test
21) Name the hematological tests that help diagnose and monitor disease progression and drug effects.
22) Normal values in hematological tests
23) How do the values of red blood cells, white blood cells, platelets, reticulocytes... reflect the patient's condition?
24) List 3 causes of high blood urea (> 50 mg/dl)
25) List 3 cytotoxic drugs that can increase blood uric acid.
26) Which enzyme increases earliest in myocardial infarction? Why?
27) Hematocrite changes in which pathological cases?
28) In which pathological cases does the erythrocyte sedimentation rate increase?
Distinguish right from wrong
29) Urea is the main degradation product of protein, formed in the intestine and excreted mainly in the feces.
30) Fasting blood glucose levels higher than 140 mg/dl are considered pathological.
31) ASAT is also known as GOT
32) ALAT is also known as GPT
33) Alkaline phosphatase is excreted in the bile.
Choose the correct answer
34. Creatinine is excreted in urine mainly due to:
AAGFR
BBRenal tubular secretion
CCNegative tubular secretion or reabsorption
DDA and C are correct
35. Diseases that lead to hyperglycemia
A. Diabetes
B. Cushing's syndrome, hyperthyroidism
C. Due to use of drugs such as Hydrochlorothiazide
D. A, B, C are correct
36. Causes of hypoglycemia
A. Insulin Overdose
B. Hypopituitarism, thyroid deficiency
C. Pancreatic tumors, liver failure
D. A, B, C are correct 37. The most specific enzyme for the liver:
A. CK
B. Alkaline phosphatase
C. ASAT
D. ALAT
LESSON 7
USE OF DRUG IN SPECIAL SUBJECTS
LEARNING OBJECTIVES
List the subjects that need special monitoring when taking the drug, and the reasons why they need to be concerned.
List some groups of drugs that should not be used or should be used with caution in the above subjects.
Analyze changes in the effects and impacts of drugs when using drugs for the above subjects compared to normal people.
Present issues to note when using drugs for these subjects.
above.
CONTENT
1. NEWBORNS AND CHILDREN UNDER 1 YEAR OLD
1.1. DRUG ABSORPTION
1.1.2. Oral and rectal route
o Stomach pH is higher than in older children because they still secrete less acid.
o The gastric emptying time is long, but intestinal motility is stronger than in older children.
o Immature intestinal mucosa. Incomplete enzymes Therefore:
o Slows absorption of weak acids: phenobarbital, paracetamol, aspirin
o Increases absorption of weak bases: theophylline, ampicillin
o Poor release of active drug: chloramphenicol palmitate cannot separate the ester group to release the free form, reducing absorption.
o But absorption through the rectum is good
1.1.3. By injection
Skeletal muscle system is still weak, blood volume is low, easy to constrict due to reflex, water volume is high. Therefore, absorption is slow and irregular. Should be injected intravenously.
1.1.4. Through the skin
The stratum corneum is still thin and easily absorbs medicine. Therefore:
Be careful with corticosteroids
Do not rub strong essential oils: menthol, camphor, because strong irritation can easily cause respiratory reflex.
Do not use irritants: salicylic acid, iodine, alcohol
1.2. DRUG DISTRIBUTION
Plasma protein content is still low in both quantity and quality, so free drug is high or there is competition between endogenous substances and drugs.
Drugs enter the central nervous system faster and in greater quantities
1.3. DRUG METABOLISM
In the first year, the enzyme activity is poor, but then suddenly increases, sometimes 5 times that of adults.
1.4. DRUG EXCRETION
Under 1 year old, kidney function is still poor so the half-life of the drug is long.
Therefore, the dose of the drug needs to be reduced and the frequency of doses should be less. After one year, the kidneys function like adults.
Some points to note when giving medicine to children
1. Dosage for children
Children should not be treated as miniature adults. Dosage for children should take into account age, weight, and body surface area, and should be based on the ability of the liver and kidneys to function properly. Dosage for children is usually calculated in mg/kg.
2. Choosing a drug for children
Oral medication
Oral medications are the safest and most convenient. Medications should have attractive colors and flavors to make them easier for children to take, making them feel interested and willing to take the medication, which will help the treatment to be successful.
For children under 5 years old, the medicine should be given in liquid form. Older children can take medicine in solid form. In many cases, the tablets are crushed with a spoon and then mixed with something like honey, fruit juice, etc. for the child to drink. Do not mix the medicine with the child's food.
Injectable drugs
As analyzed above, intramuscular injection should be avoided for young children. With intravenous infusion, attention should be paid to slow infusion rate and the volume of fluid allowed for use in children.
Rectal suppositories
This is a convenient route of administration because children often refuse to take medicine. This route of administration can achieve a quick effect, suitable for children with severe vomiting, coma or intestinal obstruction, and parents can easily intervene. However, do not abuse this route of administration because it can cause local irritation.
Aerosol medicine
Children under 5 years old have difficulty using metered dose inhalers because they do not know how to coordinate inhalation and exhalation when spraying the medicine, so a nebulizer or spray booth (for children under 3 years old, a mask is required) is more suitable.
2. PREGNANT WOMEN
2.1. USE OF MEDICATION FOR PREGNANT WOMEN
2.1.1 Effects of drugs on the fetus
When a pregnant woman takes medication, most drugs cross the placenta to varying degrees and enter the fetal circulation.
The concern when using drugs in pregnant women is that the drugs enter the fetal circulation and cause harm to the fetus. Drugs used for the mother can have direct or indirect effects on the fetus. The effects of drugs on the fetus depend on when the drug is used during pregnancy.
When to take medication during pregnancy and its effects
Teratogenic substances rarely cause a single malformation. Usually, a series of malformations will occur. From the moment the egg is fertilized, pregnancy lasts for 38 weeks, and is divided into three stages: pre-embryonic, embryonic, and fetal.
Pre-embryonic period.
Lasting 17 days after the egg is fertilized, it is usually insensitive to harmful factors because the cells have not yet begun to differentiate. Drug toxicity to the fetus follows the “All or Nothing” rule.
Embryonic period
From day 18 to day 56, most of the body's organs are formed during this period. Taking medication during this period can cause abnormalities.
severe morphological effects on the child. For example, some sedatives, antibiotics, hormonal drugs, anticancer drugs: Thailidomide disaster. Each organ has a certain stage that is most sensitive to the toxicity of the drug.
Pregnancy period
From week 8-9 onwards (2nd month), lasting until birth. During this period, the body parts continue to develop and mature. The fetus is less sensitive to toxic substances. However, the parts of the fetus's body that are still at high risk are the central nervous system, eyes, teeth, ears and external genitalia. For example: tetracycline antibiotics, aminoside antibiotics. Right before labor, some drugs can still affect the fetus such as morphine...
2.1.2 Effects of drugs used by pregnant women on children after birth
Newborns may be exposed to the effects of medications given to their mothers during pregnancy. Because newborns have poor drug excretion, some medications may accumulate significantly and be toxic to the baby. Therefore, special attention should be paid to certain medications when given to pregnant women near the due date.
2.2 Classification of drug safety levels for pregnant women
The US Food and Drug Administration (FDA) has classified drugs into five categories:
Type A
Controlled studies have shown no risk to the fetus at any point during pregnancy.
Type B
Tested on animals and found no risk and not tested on pregnant women, or tested on animals with risk but no reliable evidence to prove risk to pregnant women (prednisone, insulin).
Type C
Fetal risk. Human studies are insufficient, but animal studies demonstrate a risk to the fetus; or animal studies are not available and human studies are insufficient.
Type D
There is a definite risk to the fetus. Research data or post-marketing data indicate that the drug has a risk of harm to the fetus, but the therapeutic benefit outweighs the risk.
Type X
Contraindicated in pregnant women. (Isotretinone)
Teratogenic drugs:
Alcohol, ACE inhibitors, androgens, anticonvulsants, cancer drugs, diethlstilbestrol, iodine, isotretinone, lithium, thalidomide, warfarin….
2.3 Principles in using drugs for pregnant women
- Minimize the use of drugs, should choose non-drug treatment methods
medicine.
- Avoid taking medication during the first 3 months of pregnancy.
- Use the lowest effective dose for the shortest possible time.
- Choose drugs that have been proven safe, avoid using drugs that have not been
widely used for pregnant women.
3. BREASTFEEDING WOMEN
Systemic drugs when administered to nursing mothers can be excreted in milk, to a greater or lesser extent. An example of a drug that is excreted in milk is a drug containing iodine derivatives (Lugol's solution, used to treat hyperthyroidism), which is particularly