Split (1)

train · 617k rows

text stringlengths 2 132k	source dict
Correct such that: a) There is a path in 𝐺 ( Correct ) from 𝑝 𝑙 to every process 𝑝 𝑐 ∈ Correct (i.e. 𝑝 𝑙 can reach every process in Correct). b) There exists a process 𝑝 𝑘 ∈ Correct , 𝑝 𝑘 ≠ 𝑝 𝑙 , such that there is a path in 𝐺 ( Correct ) from 𝑝 𝑘 to 𝑝 𝑙 (i.e. there is a process in Correct which can reach 𝑝 𝑙 ). The following lemma shows the necessity condition of Part a) of Property 1. It is an adaptation of Theorem 1 in . Lemma 9 There is no algorithm 𝐴 that implements a failure detector D of Class Ω in system 𝑆 𝑠 without preserving that there is a process 𝑝 𝑙 ∈ Correct such that there is a path in 𝐺 ( Correct ) from 𝑝 𝑙 to every process 𝑝 𝑐 ∈ Correct . Proof By the way of contradiction, let us assume that there is an algorithm 𝐴 that implements a failure detector D of Class Ω in system 𝑆 𝑠 without preserving that there is a process 𝑝 𝑙 ∈ Correct such that there is a path in 𝐺 ( Correct ) from 𝑝 𝑙 to every process 𝑝 𝑐 ∈ Correct (i.e. 𝑝 𝑙 can reach every process in Correct). Thus no correct process is able to reach every correct process. Let us also assume an execution E of 𝐴 in which all the messages sent through lossy-asynchronous links are lost. From Definition 1 of Ω, there is a correct process 𝑝 𝑙 and a time 𝜏 ′ such that, for all 𝜏 ≥ 𝜏 ′ , for each correct process 𝑝 𝑐 , 𝐷 . leader 𝑐 𝜏 ( ) returns 𝑝 𝑙 permanently. Let U be	{ "page_id": null, "source": 7342, "title": "from dpo" }
the set of correct processes that cannot be reached from 𝑝 𝑙 in 𝐺 ( Correct ) . Recall that, from the initial hypothesis, this set is not empty. Let us consider now another execution 𝐸 ′ of 𝐴 analogous to E except that process 𝑝 𝑙 is a non-correct process (i.e., it can be a deaf, mute, autistic or crashed process). Note that no process in U can possibly distinguish E from 𝐸 ′ since they do not receive messages from 𝑝 𝑙 nor from any other process in Correct ∖ 𝑈 . Hence, every process in U can behave exactly as in E and, for each correct process 𝑝 𝑢 ∈ 𝑈 , 𝐷 . leader 𝑢 𝜏 ( ) returns 𝑝 𝑙 permanently for all 𝜏 ≥ 𝜏 ′ , what violates Definition 1 since 𝑝 𝑙 is a non-correct process, and we reach a contradiction. The following lemma shows that, if a process 𝑝 𝑙 is the leader of the failure detector D implemented in 𝑆 𝑠 , then there must be a path of eventually-timely links from 𝑝 𝑙 to every correct process of 𝑆 𝑠 . Lemma 10 Let D be a failure detector of Class Ω. If there is a time 𝜏 ′ such that, for all 𝜏 ≥ 𝜏 ′ , 𝐷 . leader 𝑖 𝜏 ( ) = 𝑝 𝑙 for every process 𝑝 𝑖 ∈ Correct , then there must be a path in 𝐺 ( Correct ) from 𝑝 𝑙 to every other correct process (i.e. 𝑝 𝑙 must be able to reach every correct process). Proof By the way of contradiction, assume that there is an execution E of a failure detector D of Class Ω in which there is a time 𝜏 ′ such that for all	{ "page_id": null, "source": 7342, "title": "from dpo" }
𝜏 ≥ 𝜏 ′ 𝐷 . leader 𝑖 𝜏 ( ) = 𝑝 𝑙 for every correct process 𝑝 𝑖 , but 𝑝 𝑙 is not able to reach any process in 𝑈 ⊆ Correct in 𝐺 ( Correct ) . Note that, from the initial assumption, 𝑈 ≠ ∅ . Let us also assume that, in E, all the messages sent through lossy-asynchronous links are lost. Let us consider now another execution 𝐸 ′ of D analogous to E except that process 𝑝 𝑙 is a non-correct process (i.e., it can be a deaf, mute, autistic or crashed process). Note that no process in U can possibly distinguish E from 𝐸 ′ since they do not receive messages from 𝑝 𝑥 nor from any other process in Correct ∖ 𝑈 . Hence, every process in U can behave exactly as in E and, for each correct process 𝑝 𝑢 ∈ 𝑈 , 𝐷 . leader 𝑢 𝜏 ( ) returns 𝑝 𝑙 for all 𝜏 ≥ 𝜏 ′ , what violates Definition 1 since 𝑝 𝑙 is a non-correct process, and we reach a contradiction. The following lemma shows the necessity of Part b) of Property 1. Lemma 11 There is no algorithm 𝐴 that implements a failure detector D of Class Ω in system 𝑆 𝑠 without preserving that there exists a process 𝑝 𝑘 ∈ Correct , such that there is a path in 𝐺 ( Correct ) from 𝑝 𝑘 to another correct process 𝑝 𝑙 from which there is a path in 𝐺 ( Correct ) to every correct process. Proof Let us assume, by the way of contradiction, that there is an execution E of an algorithm 𝐴 that implements a failure detector D of Class Ω in system 𝑆 𝑠 not preserving that	{ "page_id": null, "source": 7342, "title": "from dpo" }
there is a correct process 𝑝 𝑘 which can reach another process 𝑝 𝑙 which can reach every correct process. Let us also assume that, in E, all the messages sent through lossy-asynchronous links are lost. Since 𝐴 implements a failure detector of Class Ω, then from Definition 1, there is a process 𝑝 𝑙 and a time 𝜏 ′ such that for all 𝜏 ≥ 𝜏 ′ 𝐷 . leader 𝑖 𝜏 ( ) = 𝑝 𝑙 for every correct process 𝑝 𝑖 . Besides, from the initial assumption, either 𝑝 𝑙 is not able to reach every other correct process, or no other correct process can reach 𝑝 𝑙 . However, from Lemma 10, there must be a path in 𝐺 ( Correct ) from 𝑝 𝑙 to every correct process, so there is nopath in 𝐺 ( Correct ) from any correct process to 𝑝 𝑙 . Let us consider now another execution 𝐸 ′ of D analogous to E except that process 𝑝 𝑙 is a deaf process. Note that 𝑝 𝑙 can only be sure that it is not a deaf process if it eventually receives messages permanently from some process. Since there is no correct process that is able to reach process 𝑝 𝑙 , then it does not have any possibility of distinguishing E from 𝐸 ′ , since process 𝑝 𝑙 does not receive messages permanently. Note also that all processes in Correct can behave exactly as in E, and they cannot distinguish E from 𝐸 ′ since process 𝑝 𝑙 sends them the same messages in both executions. Hence, for all 𝜏 ≥ 𝜏 ′ , 𝐷 . leader 𝑖 𝜏 ( ) = 𝑝 𝑙 for every correct process 𝑝 𝑖 . Since 𝑝 𝑙 is a deaf process, this	{ "page_id": null, "source": 7342, "title": "from dpo" }
violates Definition 1, and we reach a contradiction. Theorem 3 There is no algorithm 𝐴 that implements a failure detector D of Class Ω in a system 𝑆 𝑠 without preserving Property 1. Proof Direct from Lemma 9 and Lemma 11. 6.2. Implementing Ω in 𝑆 𝑝 We present in this section an algorithm (called 𝐴 Ω ) which implements a failure detector of Class Ω fulfilling weak assumptions with respect to the number of faulty processes, synchrony, knowledge of membership and the number of eventually-timely links. Thus, 𝐴 Ω works in a system (we call it 𝑆 𝑝 ) with degenerative Byzantine failures as in S, where up to n processes can be faulty, with partial synchrony, where the membership is unknown, and preserving Property 1 (which is minimal with respect to the number of eventually-timely links). 6.2.1. The Partially Synchronous System 𝑆 𝑝 Let 𝑆 𝑝 be a system such as S but with the following differences. 𝑆 𝑝 is partially synchronous , that is, the maximum time needed by each process 𝑝 𝑖 ∈ 𝑆 𝑝 to execute a step is bounded but unknown by every process, and the time needed to receive a sent message is bounded but also unknown. We assume that in system 𝑆 𝑝 there may be any number of faulty processes (i.e., 𝑓 ≤ 𝑛 ). Regarding membership, 𝑆 𝑝 is weaker than S in the sense that, similarly to S, in 𝑆 𝑝 each process 𝑝 𝑖 has no initial information about any other process but itself. However, unlike S, processes do not know the size n of the system. 𝑆 𝑝 has two types of links: eventually-timely and lossy-asynchronous . We consider that, in 𝑆 𝑝 , every process 𝑝 𝑖 can send messages to every other process 𝑝 𝑘	{ "page_id": null, "source": 7342, "title": "from dpo" }
, 𝑝 𝑘 ≠ 𝑝 𝑖 , using a different and unidirectional link. Note that, unlike S, and for the sake of generalization and avoiding a trivial solution, we eliminate the possibility that a process 𝑝 𝑖 sends messages to itself. Thus, we prevent a process 𝑝 𝑖 from trivially knowing if it is a deaf or mute process. Recall that, in 𝑆 𝑝 , 𝐺 ( Correct ) needs not be a complete graph of eventually-timely links. Hence, rebroadcasts are necessary to effectively reach the destination of each message (if possible). However, we assume that every process can irrefutably validate the legitimacy of every message no matter it has been rebroadcast. This can be enforced by using digital signatures with asymmetric encryption. Each message could include in its header both the signature and the public key necessary to verify the signature. Thus, if a mortal Byzantine process tries to alter a legitimate message during a rebroadcast, it would not be able to correctly sign the altered message and a correct process will detect the attack and discard the altered message upon reception. Finally, we also assume that 𝑆 𝑝 satisfies Property 1, which was proved in Theorem 3 to be a necessary condition for the implementability of a failure detector of Class Ω. 6.2.2. Description of Algorithm 𝐴 Ω in 𝑆 𝑝 Fig. 3 presents Algorithm 𝐴 Ω which implements a failure detector D of Class Ω in system 𝑆 𝑝 , as we will prove below. The algorithm is based on information processes diffuse about their suspicions on the processes they know. Download: Download high-res image (251KB) Download: Download full-size image Fig. 3. Algorithm 𝐴 Ω for implementing a failure detector D of Class Ω in System Sp, i.e., in a partially synchronous system with unknown membership, degenerative	{ "page_id": null, "source": 7342, "title": "from dpo" }
Byzantine failures and where f ≤ n (code of pi). Each process uses some variables to record its current knowledge of the state of the system. In order to simplify the algorithm, these variables are considered dynamic in the sense that space is allocated and initialized as needed the first time some particular value is accessed. In particular, variable susp 𝑖 is a two dimensional matrix used by process 𝑝 𝑖 to store, at each row j, the suspicions process 𝑝 𝑗 has of every other process 𝑝 𝑘 known by 𝑝 𝑗 . Variable correct 𝑖 stores the set of processes which process 𝑝 𝑖 considers to be correct. Process 𝑝 𝑖 considers that process 𝑝 𝑗 is correct if 𝑝 𝑖 periodically receives messages form 𝑝 𝑗 and those messages are consistent with the messages previously received from 𝑝 𝑗 . If process 𝑝 𝑖 receives a message form 𝑝 𝑗 which is inconsistent with the previous messages received from 𝑝 𝑗 , then 𝑝 𝑗 must be a Byzantine process. Byzantine processes are stored in variable known _ byzantine 𝑖 . When a Byzantine process is detected, it will never again be considered to be correct. A process 𝑝 𝑖 uses Task T1 to propagate ( HB , next _ seq 𝑖 [ 𝑖 ] , susp 𝑖 [ 𝑖 ] , 𝑖 ) messages periodically (each η units of time) reporting, to all processes, the system status as known by process 𝑝 𝑖 (Lines 6–8). These messages are heartbeats (HB) which tell each receiver process that 𝑝 𝑖 is a non-crashed process, so the receiver can update its view of the system status. These messages diffuse the current suspicions of process 𝑝 𝑖 in susp 𝑖 [ 𝑖 ] , and include their sequence number next	{ "page_id": null, "source": 7342, "title": "from dpo" }
_ seq 𝑖 [ 𝑖 ] . A process 𝑝 𝑖 uses Task T2 (roughly) to learn and report about the identity of processes and the status known by the processes that form the membership (Lines 9–27), to acknowledge the sender heartbeats (Lines 28–33), to increase the level of suspicions of processes from which 𝑝 𝑖 does not receive heartbeats on time (Lines 34–38), and to compute and return the leader process (Lines 39–46). Each ( HB , next _ seq 𝑘 , susp _ 𝑝 𝑘 , 𝑘 ) message received has a sequence number next _ seq 𝑘 which starts from 1 and is increased each time the HB with the previous sequence number is acknowledged by some other process in the system (done at Line 32). Thus, it is possible to know that a HB message is newer than the last one received from the same process 𝑝 𝑘 (as checked at Line 16). Note that only new HB messages are taken into consideration. Note also that process 𝑝 𝑖 stores in next _ seq 𝑖 [ 𝑘 ] , 𝑘 ≠ 𝑖 the sequence number of the newest HB message received from process 𝑝 𝑘 (Line 24). Since the time of reception of these heartbeats by each process 𝑝 𝑖 is bounded but variable and unknown (due to the fact that 𝑆 𝑝 is partially synchronous), 𝑝 𝑖 may temporarily (and erroneously) believe that it does not receive HB messages from 𝑝 𝑘 on time because 𝑝 𝑘 is a non-correct process. Each process 𝑝 𝑖 uses susp 𝑖 [ 𝑘 ] to count the number of times that process 𝑝 𝑘 has suspected each other process to be a non-correct process. Each process 𝑝 𝑖 keeps in variable Timeout 𝑖 [ 𝑘 ] the time	{ "page_id": null, "source": 7342, "title": "from dpo" }
to wait for a HB message from 𝑝 𝑘 . Each time it receives a HB message from process 𝑝 𝑘 (not in known _ byzantine 𝑖 , what is tested at Line 16) on time, it updates 𝑝 𝑘 suspicions, adds it to correct 𝑖 , sends back an acknowledgment, updates the sequence number of the last HB message received and resets the timer associated with process 𝑝 𝑘 (Lines 20–26). Each time the timer associated with 𝑝 𝑘 expires (Lines 34–38), 𝑝 𝑘 is removed from correct 𝑖 , its suspicions are increased as well as its corresponding timeout, and the timer is reset to the new timeout value. When process 𝑝 𝑖 receives a ( HB , next _ seq 𝑘 , susp 𝑘 , 𝑘 ) message, it relays it trying to reach all processes (Line 10). To avoid messages being permanently in the network, each message is only forwarded once (Line 9). Finally, Function leader 𝑖 ( ) (Lines 39–46) returns the current leader of process 𝑝 𝑖 each time it is invoked. The leader will be the process with the minimum value of suspicions in susp 𝑖 among the processes in 𝑐 𝑜 𝑟 𝑟 𝑒 𝑐 𝑡 𝑖 , and, in case of a tie, we use the minimum identity of these processes with the minimum suspicions. To clarify the code, we use the auxiliary variable punish 𝑖 to temporarily store these minimum values per process. 6.2.3. Correctness of Algorithm 𝐴 Ω in 𝑆 𝑝 In this section we prove the correctness of Algorithm 𝐴 Ω . We start proving that, eventually, mute, deaf, autistic and mortal Byzantine processes are not considered correct anymore. Lemma 12 Eventually, no correct process 𝑝 𝑖 considers a mute, deaf, autistic or mortal Byzantine process to be	{ "page_id": null, "source": 7342, "title": "from dpo" }
correct. Proof Note that mute processes eventually stop sending heartbeats, so there is a time after which their timers expire forever. Thus, at Line 35 they will be removed from correct 𝑖 by all correct processes, and Line 22 will never again be executed. Deaf processes will eventually stop receiving ACK_HB messages from other processes. Hence, they will stop increasing their sequence numbers since they will never reach Line 32. Hence, all their future HB messages will have the same sequence number. Then, when a correct process receives their HB messages, the condition of Line 16 will never again be satisfied, so their timers will always expire. Thus, every correct process 𝑝 𝑖 will remove them from correct 𝑖 at Line 35. Recall that autistic processes are both mute and deaf, so the previous arguments also apply to autistic processes. Finally, mortal Byzantine processes will eventually stop sending messages (when they crash). Hence, after they crash, they will be permanently removed from correct 𝑖 at Line 35, since their timers will expire forever after. Lemma 13 Let 𝑝 𝑖 and 𝑝 𝑘 be any two correct processes. Eventually, every HB message from 𝑝 𝑘 is received by 𝑝 𝑖 before timer 𝑖 ( 𝑘 ) expires. Proof Since every time timer 𝑖 ( 𝑘 ) expires, Timeout 𝑖 [ 𝑘 ] is increased (at Line 37) and, in System 𝑆 𝑝 , the time required by a message to arrive to its destination is bounded, eventually, Timeout 𝑖 [ 𝑘 ] will be enough to allow the reception of every message from process 𝑝 𝑘 before timer 𝑖 ( 𝑘 ) expires. Corollary 3 Eventually, suspicions on correct processes stop increasing. Proof From Lemma 13, eventually, all processes receive the HB messages from all processes before their timers expire. Since	{ "page_id": null, "source": 7342, "title": "from dpo" }
suspicions are only increased at Line 36 (when timers expire), eventually, suspicions on correct processes stop increasing. Theorem 4 Algorithm 𝐴 𝛺 of Fig. 3 implements a failure detector D of Class Ω in 𝑆 𝑝 . Proof From Lemma 12, eventually, no correct process 𝑝 𝑖 considers a mute, deaf, autistic or mortal Byzantine process to be correct. Hence, eventually, the leader process returned by Function leader 𝑖 ( ) at every correct process will be a correct process. Besides, from Corollary 3, eventually, suspicions on correct processes stop increasing. Thus, there is a time after which all the HB messages sent by a process with successive sequence numbers have the same suspicions. Hence, there is a time after which the suspicions collected by all correct processes are the same, so all of them will choose the same leader when Function leader 𝑖 ( ) is invoked. 7. Conclusions In this paper we have studied consensus in asynchronous systems with unknown membership under a failure model with 𝑓 < 𝑛 / 3 degenerative Byzantine failures. In this model, every faulty process is a Byzantine process (i.e., it deviates from its specification) such that eventually degenerates and makes a physical or a transmission failure permanently. A physical failure is that in which the process crashes permanently, and a transmission failure happens when a process (intentionally or unintentionally) omits a communication operation. The main advantage of this degenerative Byzantine failure model with respect to the classical Byzantine model is that Consensus can be solved in an pure asynchronous system augmented with a failure detector such that both of them are totally decoupled. This independence between consensus and failure detectors allows simplifying the design, development, correctness and maintenance of the algorithms because the designers can focus on the properties the	{ "page_id": null, "source": 7342, "title": "from dpo" }
consensus algorithm must preserve, based only on the properties supplied by the failure detector. From a practical point of view, several examples where this failure model is useful have been previously given in . In this paper we have presented a consensus algorithm 𝐴 𝐶 which is simple and optimal with respect to the maximum number of faulty processes. It is optimal because 𝐴 𝐶 solves Consensus when 𝑓 < 𝑛 / 3 , being f the maximum number of faulty processes and n the number of processes in the system , . Trying to make 𝐴 𝐶 simple, it uses a failure detector of Class Ω and a broadcast primitive (RFLOB) to communicate messages among processes. To our knowledge, 𝐴 𝐶 is the first algorithm that solves Consensus with a decoupled failure detector, unknown membership and the degenerative Byzantine failures. We have also introduced a definition of Ω adapted from the crash failure model of to our failure model with degenerative Byzantine failures, and an algorithm 𝐴 Ω which implements a failure detector of Class Ω. Furthermore, we have proven in this paper that 𝐴 Ω can be implemented with unknown membership and minimum connectivity requirements (i.e., the minimum communication reliability and synchrony properties) in a system with degenerative Byzantine failures. To our knowledge, all failure detector classes in systems with Byzantine failures, present in the literature prior to this paper, cannot be implemented when the membership is unknown. Thus, 𝐴 Ω covers this gap. Finally, to simplify the consensus algorithm, we have introduced the RFLOB primitive which guarantees that correct processes deliver the same sequence of messages if they were broadcast by the same process, and the messages broadcast by each process are delivered by all correct processes following the same FIFO and local order . We	{ "page_id": null, "source": 7342, "title": "from dpo" }
have described and proven the correctness of algorithm 𝐴 RFLOB which implements this RFLOB primitive for systems with unknown membership and 𝑓 < 𝑛 / 3 classical Byzantine processes . Also, to our knowledge, this algorithm 𝐴 RFLOB is the first implementation of a broadcast primitive with reliability properties, FIFO and local reception and unknown membership in a system with the classical Byzantine processes of (note that our degenerative Byzantine failure model is a subset of this classical Byzantine failure model). Thus we show that Consensus is implementable using an Ω failure detector and the RFLOB broadcast primitive, in a system with degenerative Byzantine failures even with unknown membership. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References Marcos K. Aguilera, Carole Delporte-Gallet, Hugues Fauconnier, Sam Toueg On implementing omega in systems with weak reliability and synchrony assumptions Distrib. Comput., 21 (4) (2008), pp. 285-314 CrossrefView in ScopusGoogle Scholar Marcos Kawazoe Aguilera, Carole Delporte-Gallet, Hugues Fauconnier, Sam Toueg Stable leader election Distributed Computing, Proceedings of the 15th International Conference DISC 2001, Lisbon, Portugal, October 3–5, 2001 (2001), pp. 108-122 Google Scholar Gabriel Bracha Asynchronous byzantine agreement protocols Inf. Comput., 75 (2) (1987), pp. 130-143 View PDF View articleView in ScopusGoogle Scholar Gabriel Bracha, Sam Toueg Asynchronous consensus and broadcast protocols J. ACM, 32 (4) (1985), pp. 824-840 View in ScopusGoogle Scholar Tushar Deepak Chandra, Vassos Hadzilacos, Sam Toueg The weakest failure detector for solving consensus J. ACM, 43 (4) (July 1996), pp. 685-722 View in ScopusGoogle Scholar Tushar Deepak Chandra, Sam Toueg Unreliable failure detectors for reliable distributed systems J. ACM, 43 (2) (March 1996), pp. 225-267 View in ScopusGoogle Scholar	{ "page_id": null, "source": 7342, "title": "from dpo" }
Siobhàn Clarke, Elisa Baniassad Aspect-Oriented Analysis and Design Addison-Wesley Professional (2005) Google Scholar Miguel Correia, Giuliana Santos Veronese, Nuno Ferreira Neves, Paulo Verissimo Byzantine consensus in asynchronous message-passing systems: a survey Int. J. Critical Comput.-Based Syst., 2 (2) (2011), pp. 141-161 CrossrefView in ScopusGoogle Scholar Edsger W. Dijkstra On the role of scientific thought Selected Writings on Computing: A Personal Perspective, Springer (1982), pp. 60-66 CrossrefGoogle Scholar Danny Dolev, Cynthia Dwork, Larry Stockmeyer On the minimal synchronism needed for distributed consensus J. ACM, 34 (1) (January 1987), pp. 77-97 View in ScopusGoogle Scholar Assia Doudou, Benoît Garbinato, Rachid Guerraoui, André Schiper Muteness failure detectors: specification and implementation Proceedings of the Third European Dependable Computing Conference on Dependable Computing, EDCC-3, Springer-Verlag, London, UK (1999), pp. 71-87 CrossrefView in ScopusGoogle Scholar Assia Doudou, André Schiper Muteness detectors for consensus with byzantine processes Proceedings of the Seventeenth Annual ACM Symposium on Principles of Distributed Computing, PODC '98, ACM, New York, NY, USA (1998), p. 315 Google Scholar Antonio Fernández, Ernesto Jiménez, Sergio Arévalo Minimal system conditions to implement unreliable failure detectors 12th IEEE Pacific Rim International Symposium on Dependable Computing, PRDC 2006, 18–20 December, 2006, University of California, Riverside, USA (2006), pp. 63-72 2006 Google Scholar Colin J. Fidge Logical time in distributed computing systems IEEE Computer, 24 (8) (1991), pp. 28-33 View in ScopusGoogle Scholar Michael J. Fischer, Nancy A. Lynch, Michael S. Paterson Impossibility of distributed consensus with one faulty process J. ACM, 32 (2) (April 1985), pp. 374-382 View in ScopusGoogle Scholar Roy Friedman, Achour Mostefaoui, Michel Raynal Simple and efficient oracle-based consensus protocols for asynchronous byzantine systems IEEE Trans. Dependable Secure Comput., 2 (1) (January 2005), pp. 46-56 View in ScopusGoogle Scholar Vassos Hadzilacos, Sam Toueg A modular	{ "page_id": null, "source": 7342, "title": "from dpo" }
approach to fault-tolerant broadcasts and related problems Technical Report Ithaca, NY, USA (1994) Google Scholar Jackson Daniel Software Abstractions: Logic, Language, and Analysis MIT Press (2012) Google Scholar Ernesto Jiménez, Sergio Arévalo, Antonio Fernández Implementing unreliable failure detectors with unknown membership Inf. Process. Lett., 100 (2) (October 2006), pp. 60-63 View PDF View articleView in ScopusGoogle Scholar Kim Potter Kihlstrom, Louise E. Moser, P.M. Melliar-Smith Solving consensus in a byzantine environment using an unreliable fault detector Alain Bui, Marc Bui, Vincent Villain (Eds.), On Principles Of Distributed Systems, Proceedings of the 1997 International Conference, Chantilly, France, December 10–12, 1997, Hermes (1997), pp. 61-76 Google Scholar Leslie Lamport Time, clocks, and the ordering of events in a distributed system Commun. ACM, 21 (7) (1978), pp. 558-565 View in ScopusGoogle Scholar Leslie Lamport, Robert Shostak, Marshall Pease The byzantine generals problem ACM Trans. Program. Lang. Syst., 4 (3) (July 1982), pp. 382-401 View in ScopusGoogle Scholar Dahlia Malkhi, Michael K. Reiter A high-throughput secure reliable multicast protocol J. Comput. Secur., 5 (2) (1997), pp. 113-128 View in ScopusGoogle Scholar Dahlia Malkhi, Michael K. Reiter Unreliable intrusion detection in distributed computations 10th Computer Security Foundations Workshop, CSFW '97, Rockport, Massachusetts, USA, June 10–12, 1997, IEEE Computer Society (1997), pp. 116-125 Google Scholar Friedemann Mattern Virtual time and global states of distributed systems Parallel and Distributed Algorithms, North-Holland (1988), pp. 215-226 Google Scholar Achour Mostéfaoui, Michel Raynal Signature-free broadcast-based intrusion tolerance: never decide a byzantine value Principles of Distributed Systems - Proceedings of the 14th International Conference, OPODIS 2010, Tozeur, Tunisia, December 14–17, 2010 (2010), pp. 143-158 CrossrefView in ScopusGoogle Scholar Achour Mostéfaoui, Michel Raynal Intrusion-tolerant broadcast and agreement abstractions in the presence of byzantine processes IEEE Trans. Parallel Distrib. Syst., 27 (4) (2016),	{ "page_id": null, "source": 7342, "title": "from dpo" }
pp. 1085-1098 View in ScopusGoogle Scholar M. Pease, R. Shostak, L. Lamport Reaching agreement in the presence of faults J. ACM, 27 (2) (April 1980), pp. 228-234 View in ScopusGoogle Scholar Kenneth J. Perry, Sam Toueg Distributed agreement in the presence of processor and communication faults IEEE Trans. Softw. Eng., 12 (3) (1986), pp. 477-482 View in ScopusGoogle Scholar Michel Raynal Communication and Agreement Abstractions for Fault-Tolerant Asynchronous Distributed Systems Synthesis Lectures on Distributed Computing Theory, Morgan & Claypool Publishers (2010) Google Scholar Michael K. Reiter Secure agreement protocols: reliable and atomic group multicast in rampart CCS '94, Proceedings of the 2nd ACM Conference on Computer and Communications Security, Fairfax, Virginia, USA, November 2–4, 1994. (1994), pp. 68-80 View in ScopusGoogle Scholar T.K. Srikanth, Sam Toueg Simulating authenticated broadcasts to derive simple fault-tolerant algorithms Distrib. Comput., 2 (2) (1987), pp. 80-94 View in ScopusGoogle Scholar Sam Toueg Randomized byzantine agreements Proceedings of the Third Annual ACM Symposium on Principles of Distributed Computing, Vancouver, B.C., Canada, August 27–29, 1984 (1984), pp. 163-178 View in ScopusGoogle Scholar Josef Widder, Martin Biely, Günther Gridling, Bettina Weiss, Jean-Paul Blanquart Consensus in the presence of mortal byzantine faulty processes Distrib. Comput., 24 (6) (2012), pp. 299-321 CrossrefView in ScopusGoogle Scholar Cited by (1) An in-depth and insightful exploration of failure detection in distributed systems 2024, Computer Networks Show abstract ☆ This work has been partially funded by the Ministry of Economy and Competitiveness (MINECO) under project CloudDB (TIN2016-80350), and by the Regional Government of Madrid (CM) under project EDGEDATA (P2018/TCS-4499). © 2019 Elsevier Inc. Recommended articles The complexity of planar Boolean #CSP with complex weights Journal of Computer and System Sciences, Volume 107, 2020, pp. 1-27 Heng Guo, Tyson Williams View PDF Collision-free network exploration Journal of Computer	{ "page_id": null, "source": 7342, "title": "from dpo" }
and System Sciences, Volume 86, 2017, pp. 70-81 Jurek Czyzowicz, …, Dominik Pająk View PDF Exploiting hidden structure in selecting dimensions that distinguish vectors Journal of Computer and System Sciences, Volume 82, Issue 3, 2016, pp. 521-535 Vincent Froese, …, Manuel Sorge View PDF Show 3 more articles Article Metrics Citations Citation Indexes 1 Captures Mendeley Readers 7 View details About ScienceDirect Remote access Advertise Contact and support Terms and conditions Privacy policy Cookies are used by this site. Cookie Settings All content on this site: Copyright © 2025 Elsevier B.V., its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies. For all open access content, the relevant licensing terms apply. × Chat with an article Save up to 50% of your literature research time by asking your questions to an article. Try for free	{ "page_id": null, "source": 7342, "title": "from dpo" }
Title: Microsoft PowerPoint - Failure Detectors.pptx URL Source: Published Time: 2011-04-14T15:27:57.000Z Markdown Content: Failure Detectors Distributed Systems Instructor: Ajay Kshemkalyani Failure Detectors Presented by, Archana Bharath Lakshmi 1• Failure detector is an application that is responsible for detection of node failures or crashes in a distributed system. • A failure detector is a distributed oracle that Failure Detector • A failure detector is a distributed oracle that provides hints about the operational status of other processes 2Why Failure Detectors • The design and verification of fault- tolerant distributed system is a difficult problem. • The detection of process failures is a crucial problem, system designers have to cope withproblem, system designers have to cope with in order to build fault tolerant distributed platforms 3Synchronous Vs Asynchronous • A distributed system is synchronous if: – there is a known upper bound on the transmission delay of messages – there is a known upper bound on the processing– there is a known upper bound on the processing time of a piece of code • A distributed system is asynchronous if: – there is no bound on the transmission delay of messages – there is no bound on the processing time of a piece of code 4Why Failure Detectors cont… • To stop waiting or not to stop waiting? • Unfortunately, it is impossible to distinguish with certainty a crashed process from a very slow process in a purely asynchronousslow process in a purely asynchronous distributed system. • Look at two major problems • Consensus • Atomic Broadcast 5• The problem can be defined with a safety and a liveness property. • The safety property stipulates that “nothing bad ever happens” Liveness & Safety bad ever happens” • The liveness property stipulates that “something good eventually happens” 6‘q’ not crashed • The	{ "page_id": null, "source": 7344, "title": "from dpo" }
message from q to p is only very slow. • Assuming that ‘q’ has crashed will violate the safety property q p Slow 7‘q’ has crashed • To prevent the bad previous scenario from occurring, p must wait until it gets q’s message. • It is easy to see that p will wait forever, and the liveness property of the application will never be satisfied q p 8Characterizing Failure Detectors • Completeness – Suspect every process that actually crashes • Accuracy – Limit the number of correct processes that are– Limit the number of correct processes that are suspected 9Completeness • Strong Completeness – Eventually, every crashed process is permanently suspected by every correct process • Weak Completeness• Weak Completeness – Eventually, every crashed process is permanently suspected by some correct process 10Strong Completeness 11Weak Completeness 12Accuracy • Strong Accuracy – A process is never suspected before it crashes by any correct process • Weak Accuracy• Weak Accuracy – Some correct process never suspected by any correct process Perpetual Accuracy! As these properties hold all the times 13Eventual Accuracy • Eventual Strong Accuracy – After a time, correct processes do not suspect correct processes • Eventual Weak Accuracy• Eventual Weak Accuracy – After a time, some correct process is not suspected by any correct process 14Failure Detector Classes Completeness Accuracy Strong Weak Eventual Strong Eventual Weak Strong Perfect Strong Eventually EventuallyStrong Perfect PPPP Strong SSSS Eventually Perfect PPPP Eventually Strong SSSS Weak vvvv Weak WWWW vvvv Eventually Weak WWWW0 15Reducibility • A Failure detector D is reducible to another failure detector D’ if there exist a reduction algorithm TD -> D’ that transforms D to D’. • Then• Then – D’ is Weaker than D (i.e) D D’ • If D D’ and D’ D then D and D’ are	{ "page_id": null, "source": 7344, "title": "from dpo" }
equivalent (i.e) D ≡ D’ • Suppose a given algorithm ‘A’ requires failure detector D’, but only D is available. 16Example 17• PPPP v ;v ;v ;v ; SSSS W ; PW ; PW ; PW ; P v ;v ;v ;v ; SSSS WWWW • vvvv PPPP ;;;; WWWW S ;S ;S ;S ; vvvv PPPP ;;;; W SW SW SW S • PPPP ≡ v ;v ;v ;v ; SSSS ≡ W ; PW ; PW ; PW ; P ≡ v ;v ;v ;v ; SSSS ≡ WWWW Reducibility of FD • Hence if we solve a problem for four failure detectors with strong completeness, the problem is automatically solved for the remaining four failure detectors. 18Comparing Failure detectors by Reducibility vvvvvvvv 19Failure Detectors : Reducibility • Two failure detectors are equivalent if they are reducible to each other. • Failure detector with weak completeness is equivalent to corresponding failure detector with strong completeness.strong completeness. • P ≡ v ; P ≡ v ; S ≡ W ; S ≡ W • Solving a problem for the four failure detectors with strong completeness, automatically solves for the remaining four failure detectors. 20Weak to Strong Completeness • Every process p executes the following: • Output p← Null • cobegin – //Task 1: repeat forever– //Task 1: repeat forever • suspects p←D p {p queries its local failure detector module D p} • send(p, suspects p) to all other processes. – //Task 2: when receive (q, suspects q) for a process q • output p← output p ∪ suspects q − {q} {output p emulates E p} • coend 21A B F,C Weak to Strong Completeness F E C D E E,C 22A B C,EC,E Weak to Strong Completeness E,C F E C D C,E 23The consensus problem •	{ "page_id": null, "source": 7344, "title": "from dpo" }
Termination : Every correct process eventually decides some value. • Uniform integrity : Every process decides at most once. • Agreement : No two correct processes decide• Agreement : No two correct processes decide differently. • Uniform validity : If a process decides a value v, then some process proposed v. • It is widely known that the consensus cannot be solved in asynchronous systems in the presence of even a single crash failure 24Solutions to the consensus problem • P ≡ v ; P ≡ v ; S ≡ W ; S ≡ W • Solving a problem for the four failure detectors with strong completeness, automatically solves for the remaining four failure detectorsfor the remaining four failure detectors • Since P is reducible to S and P is reducible to S. • The algorithm for solving consensus using S also solve consensus using P. • The algorithm for solving consensus using S also solve consensus using P. 25Consensus using SSSS 2627Work for up to f < n/2 crashes 1 2 3 4 • Processes are numbered 1, 2, …, n • They execute asynchronous rounds • In round r , the coordinator is Solving Consensus using s : Rotating Coordinator Algorithms 28 • In round r , the coordinator is process (r mod n) + 1 • In round r , the coordinator: - tries to impose its estimate as the consensus value - succeeds if does not crash and it is not suspected by S• The algorithm goes through – three Asynchronous stages • Each stage has several asynchronous rounds – Each round has 2 tasks » Task 1 • Four asynchronous phases Consensus using SSSS » Task 2 • In the first stage, several decision values are proposed • In second stage, a value gets locked:	{ "page_id": null, "source": 7344, "title": "from dpo" }
no other decision value is possible • In the third and final stage, the processes decide on the locked value and consensus is reached. 29• Task 1 – Phase1 • Every process ‘p’ sends – Current estimate to coordinator Cp – Round number tsp – Phase 2 • Cp gathers (n+1)/2 estimates • Selects one with largest time stamp estimatep • Send the new estimate to all processes – Phase 3 Consensus using SSSS – Phase 3 • Each process ‘p’ – May receive estimatep » Send an ack to Cp – May not receive estimatep » Send an nack to Cp (suspecting Cp has crashed) – Phase 4 • Waits for (n+1)/2 (acks or nacks) – If all are acks then estimatep is locked – Cp broadcasts the decided value estimatep • Task 2 – If a process ‘p’ receives a broadcast on decided value and has not already decided • Accepts the value 301 2 2,ts2 Consensus using SSSS Let ts2 < ts1 < ts3 3 3,ts3 311 2 Estp =3 Consensus using SSSS 3 Estp =3 321 2 ack Consensus using SSSS 3 ack 333 2 3 Consensus using SSSS 3 Locks 3 and broad casts 3 343 3 Consensus using SSSS 3 Locks 3 and broad casts 35Consensus using SSSS 36Consensus using S cont…S cont…S cont…S cont… 37Consensus using S cont…S cont…S cont…S cont… 38Atomic Broadcast • Informally, atomic broadcast requires that all correct processes deliver the same set of messages in the same order (i.e., deliver the same sequence of messages).same sequence of messages). • Formally atomic broadcast can be defined as a reliable broadcast with the total order property • Chandra and Toueg showed that the result of consensus can be used to solve the problem of atomic broad cast. 39• Reliable Broadcast –	{ "page_id": null, "source": 7344, "title": "from dpo" }
Validity : If the sender of a broadcast message m is non-faulty, then all correct processes eventually deliver m. – Agreement : If a correct process delivers a message m, then all correct processes deliver m. – Integrity : Each correct process delivers a message– Integrity : Each correct process delivers a message at most once. • Total Order – If two correct processes p and q deliver two messages m and m’, then p delivers m before m’ if and only if q delivers m before m’. 40Reliable Broadcast 41• The algorithm consists of three tasks : • Task 1 : – when a process p wants to A-broadcast a message m, it R_broadcasts m. • Task 2 : – a message m is added to set R_deliveredp when process p R_delivers it. Atomic Broadcast R_delivers it. • Task 3 : – when a process p A_delivers a message m, it adds m to set A_deliveredp. – Process p periodically checks whether A_undeliveredp contains messages. If it contains messages, p enters its next execution of consensus, say the kth one, and proposes A_undeliveredp as the next batch of messages to be A_delivered. 42Atomic Broadcast 43Implementation of failure detector • Task 1 : Each process p periodically sends a “p-is-alive” message to all other processes. This is like a heart-beat message that informs other processes that process p is alive. • Task 2 : If a process p does not receive a “q-is-alive” message from a process q within p(q) time units on its clock, then p adds q to its set of suspects if q is not already in the suspectadds q to its set of suspects if q is not already in the suspect list of p. • Task 3 : When a process delivers a message from	{ "page_id": null, "source": 7344, "title": "from dpo" }
a suspected process, it corrects its error about the suspected process and increases its timeout for that process. – If process p receives “q-is-alive” message from a process q that it currently suspects, p knows that its previous timeout on q was premature – p removes q from its set of suspects and increases its timeout period for process q, p(q). 44Implementation of failure detector 45Lazy failure detection protocol • A relatively simple protocol that allows a process to “monitor” another process, and consequently to detect its crash. • This protocol enjoys the nice property to rely as much as possible on application messages to do this monitoring. • The cost associated with the implementation of a failure detector incurs only when the failure detector is used (hence, it is called a lazy failure detector).lazy failure detector). • Each process pi has a local hardware clock hci that strictly monotonically increases. • The local clocks are not required to be synchronized • Every pair of processes is connected by a channel and they communicate by sending and receiving messages through channels. • Channels are not required to be FIFO 46Lazy failure detection protocol 47A short introduction to failure detectors for asynchronous Distributed SystemsDistributed Systems 48Failure Detectors-Definition Why use FD? • Based on well defined set of Abstract concepts • Not dependant on any particular implementation • Layered approach favors design, proof and portability• Layered approach favors design, proof and portability of protocol • Helps to solve impossible time-free asynchronous distributed system problems like the Consensus problem. • Eventually accurate failure detectors helps in designing indulgent algorithms. 49Asynchronous System Models Process model • A process can fail by premature halting(crashing). • A process is correct if it does not crash else it is faulty Computation models • FLP Crash-prone processes and	{ "page_id": null, "source": 7344, "title": "from dpo" }
reliable links • FLL Crash-prone processes and fair lossy links 50Asynchronous System Models Communication model Processes communicate and synchronize by exchanging messages through links. Reliable • Does not create or duplicate messages • Every message sent by Pi to Pj is eventually received by Pj Fair lossy • Does not create or duplicate messages • Can lose message • Can send infinite number of messages from one process to another 51Consensus 52Consensus • All the processes, propose a initial value and they all have to agree upon some common value proposed • Solving consensus is key to solving many problems in distributed computing (e.g., total order broadcast, atomic commit, terminating reliable broadcast) 53Consensus definition C-Validity: Any value decided is a value proposed C-Agreement: No two correct processes decide differently C-Termination: Every correct process eventuallyC-Termination: Every correct process eventually decides C-Integrity: No process decides twice C- Uniform Agreement: No two (correct or not) processes decide differently 54Consensus p1 propose(0) decide(1)propose(1) decide(0) p2 p3 decide(1) propose(0) decide(0) crash 55Uniform Consensus p1 propose(0) decide(0)propose(1) decide(0) p2 p3 decide(0) propose(0) decide(0) crash 56Eventually accurate failure detectors • Strong Completeness Eventually, all processes that crash are suspected by every correct process • Eventually Weak Accuracy There is a time after which some correct process is never suspected by the correct processes 57S-based Consensus Protocol • FLP model • Indulgent – Never violates consensus safety – Terminates when the sets contain correct values– Terminates when the sets contain correct values during a long enough period • Requires majority of correct processes (t maxi ) then esti ← est; maxi ← j endif at time (i-1)d doat time (i-1)d do if ( {p1,p2,…,pi-1} ⊆ suspectedi) then broadcast (esti,i) endif at time ( j-1)d + D for every 1 ≤ j ≤ n do if ((pj ∉ suspectedi)	{ "page_id": null, "source": 7344, "title": "from dpo" }
∧ (pi has not yet decided)) then return (esti) endif 78Thank YouThank You 79	{ "page_id": null, "source": 7344, "title": "from dpo" }
Title: Sarcopenia: revised European consensus on definition and diagnosis URL Source: Markdown Content: Abstract -------- ### Background in 2010, the European Working Group on Sarcopenia in Older People (EWGSOP) published a sarcopenia definition that aimed to foster advances in identifying and caring for people with sarcopenia. In early 2018, the Working Group met again (EWGSOP2) to update the original definition in order to reflect scientific and clinical evidence that has built over the last decade. This paper presents our updated findings. ### Objectives to increase consistency of research design, clinical diagnoses and ultimately, care for people with sarcopenia. ### Recommendations sarcopenia is a muscle disease (muscle failure) rooted in adverse muscle changes that accrue across a lifetime; sarcopenia is common among adults of older age but can also occur earlier in life. In this updated consensus paper on sarcopenia, EWGSOP2: (1) focuses on low muscle strength as a key characteristic of sarcopenia, uses detection of low muscle quantity and quality to confirm the sarcopenia diagnosis, and identifies poor physical performance as indicative of severe sarcopenia; (2) updates the clinical algorithm that can be used for sarcopenia case-finding, diagnosis and confirmation, and severity determination and (3) provides clear cut-off points for measurements of variables that identify and characterise sarcopenia. ### Conclusions EWGSOP2's updated recommendations aim to increase awareness of sarcopenia and its risk. With these new recommendations, EWGSOP2 calls for healthcare professionals who treat patients at risk for sarcopenia to take actions that will promote early detection and treatment. We also encourage more research in the field of sarcopenia in order to prevent or delay adverse health outcomes that incur a heavy burden for patients and healthcare systems. Keywords: sarcopenia, muscle strength, physical performance, muscle assessment, EWGSOP2, older people Introduction: sarcopenia 2018 ----------------------------- In 2010, the European Working Group on	{ "page_id": null, "source": 7345, "title": "from dpo" }
Sarcopenia in Older People (EWGSOP) published a sarcopenia definition that was widely used worldwide; this definition fostered advances in identifying and caring for people at risk for or with sarcopenia [1 to determine whether an update to the definition of sarcopenia was justified. This meeting took place 10 years after the gathering of the original EWGSOP, and an update was deemed necessary to reflect scientific evidence that has accumulated since then. In the decade since EWGSOP’s initial work, researchers and clinicians have explored many aspects of sarcopenia. Expert groups worldwide have published complementary definitions of sarcopenia [( and researchers have made remarkable strides in understanding muscle and its roles in health and in disease [( ( Sarcopenia is now formally recognised as a muscle disease with an ICD-10-MC Diagnosis Code that can be used to bill for care in some countries [( ( Even though healthcare professionals today are better at recognising sarcopenia, many research findings have not yet been translated into clinical practice. To this end, EWGSOP2 uses the newest evidence to delineate clear criteria and tools that define and characterise sarcopenia in clinical practice and in research populations. EWGSOP2 emphasises that practitioners have ever-increasing possibilities for preventing, delaying, treating, and sometimes even reversing sarcopenia by way of early and effective interventions. ### Health and healthcare costs of untreated sarcopenia Optimal care for people with sarcopenia is essential because the condition has high personal, social and economic burdens when untreated [( In terms of human health, sarcopenia increases risk of falls and fractures [( ( impairs ability to perform activities of daily living [( is associated with cardiac disease [( respiratory disease [( and cognitive impairment [( leads to mobility disorders [( and contributes to lowered quality of life [(	{ "page_id": null, "source": 7345, "title": "from dpo" }
loss of independence or need for long-term care placement [17 and that such disability was associated with lower quality of life (QoL) and higher healthcare costs in these target groups [( In another study, patients with sarcopenia had significantly elevated costs of care during hospitalisation—regardless of whether they were younger or older than 65 years [( ### Filling the gaps for sarcopenia awareness, care and research design Many aspects of the epidemiology and pathophysiology of sarcopenia are better understood today than 10 years ago. Researchers have identified links between muscle pathology and adverse health outcomes, and studies have also provided evidence that certain treatment strategies can help prevent or delay adverse consequences. Such new insights led EWGSOP2 to review, ‘What is new?’ and ‘How can we use this knowledge to improve care for people with sarcopenia and to guide future research studies?’ These insights include: * First, sarcopenia has long been associated with ageing and older people, but the development of sarcopenia is now recognised to begin earlier in life [( and the sarcopenia phenotype has many contributing	{ "page_id": null, "source": 7345, "title": "from dpo" }
causes beyond ageing [26, with low muscle strength overtaking the role of low muscle mass as a principal determinant [11 build a sarcopenia definition that reflects recent advances in scientific, epidemiological, and clinical knowledge about skeletal muscle, (2) identify variables that best detect sarcopenia and predict outcomes, and determine best tools for measuring each variable, (3) advise cut-off points for measured variables and (4) recommend an updated screening and assessment pathway that is easy to use in clinical practice. ### EWGSOP2 meetings, methods and endorsement by scientific organisations EWGSOP2 was organised by the European Geriatric Medicine Society (EuGMS) to include two groups of participants—a 16-member writing group and a 13-member extended group. Original members of the EWGSOP were invited to participate, and other relevant European researchers in the field were identified and recruited	{ "page_id": null, "source": 7345, "title": "from dpo" }
by feedback from involved experts and societies. The writing group met face-to-face 1–2 February 2018 near Madrid to identify how the definition and diagnostic characteristics needed to be updated, to begin the process of seeking consensus on key diagnostic and care strategies, and to designate topical areas for additional literature searches. Following this meeting, literature searches were conducted, and a preliminary draft of the manuscript was prepared and circulated for review among members of the writing and extended groups. Feedback was provided by email, and content was revised. Then a second face-to-face meeting of the writing group took place on 4 June 2018 in Amsterdam to discuss open questions and to achieve further consensus for final recommendations. This second draft was again opened for discussion by members of the Writing Group and Extended Group to produce the final draft. All EWGSOP2 members participated in manuscript content review throughout the process, and all were polled for consensus agreement on the final content. Once completed, the manuscript was reviewed and endorsed by scientific societies: EuGMS, the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), the European Society for Clinical Nutrition and Metabolism (ESPEN), International Association of Gerontology and Geriatrics European Region (IAGG-ER) and the International Osteoporosis Foundation (IOF). Sarcopenia: operational definition ---------------------------------- Sarcopenia is a progressive and generalised skeletal muscle disorder that is associated with increased likelihood of adverse outcomes including falls, fractures, physical disability and mortality. The original operational definition of sarcopenia by EWGSOP was a major change at that time, as it added muscle function to former definitions based only on detection of low muscle mass [( In these revised guidelines, muscle strength comes to the forefront, as it is recognised that strength is better than mass in predicting adverse outcomes [( ( (	{ "page_id": null, "source": 7345, "title": "from dpo" }
( Muscle quality is also impaired in sarcopenia; this term has been used to describe micro- and macroscopic aspects of muscle architecture and composition. Because of technological limits, muscle quantity and muscle quality remain problematic as primary parameters to define sarcopenia [( ( ( Detection of low physical performance predicts adverse outcomes, so such measures are thus used to identify the severity of sarcopenia. In its 2018 definition, EWGSOP2 uses low muscle strength as the primary parameter of sarcopenia; muscle strength is presently the most reliable measure of muscle function (Table ( Specifically, sarcopenia is probable when low muscle strength is detected. A sarcopenia diagnosis is confirmed by the presence of low muscle quantity or quality. When low muscle strength, low muscle quantity/quality and low physical performance are all detected, sarcopenia is considered severe. ### Table 1. 2018 operational definition of sarcopenia Probable sarcopenia is identified by Criterion 1. Diagnosis is confirmed by additional documentation of Criterion 2. If Criteria 1, 2 and 3 are all met, sarcopenia is considered severe. 1. Low muscle strength 2. Low muscle quantity or quality 3. Low physical performance Techniques for evaluating muscle quantity are available in many but not all clinical settings. As instruments and methods to evaluate muscle quality are developed and refined in the future, this parameter is expected to grow in importance as a defining feature of sarcopenia. Physical performance was formerly considered part of the core definition of sarcopenia, but others have used it as an outcome measure. We now propose using physical performance to categorise the severity of sarcopenia. To apply this definition in practice, this EWGSOP2 paper reviews tests and tools used for assessing muscle properties and performance, and it presents an updated algorithm for sarcopenia case-finding, diagnosis and severity determination. Identifying sarcopenia in clinical practice and	{ "page_id": null, "source": 7345, "title": "from dpo" }
in research ----------------------------------------------------------- ### Validated tests and tools for current use A wide variety of tests and tools are now available for characterisation of sarcopenia in practice and in research (Table 2, access to technical resources in the healthcare test setting (community, clinic, hospital or research centre), or the purpose of testing (progression monitoring, or monitoring rehabilitation and recovery). In the next sections, general descriptions of validated tests and tools are provided, and pros and cons for use of each method are noted. #### Table 2. Choosing tools for sarcopenia case finding and for measurement of muscle strength, muscle mass and physical performance in clinical practice and in research \| Variable \| Clinical practice \| Research studies \| Video for practical instruction, reference \| \| --- \| --- \| --- \| --- \| \| Case finding \| SARC-F questionnaire Ishii screening tool \| SARC-F \| Malmstrom _et al._ (2016) [12 [40 [41 \| Chair stand test (5-times sit-to-stand) \| American Academy of Orthotists & Prosthetists \| \| \| \| Skeletal muscle mass orSkeletal muscle quality \| Appendicular skeletal muscle mass (ASMM) by Dual-energy X-ray absorptiometry (DXA)* \| ASMM by DXA \| Schweitzer (2015) [[42 [43 or ASMM predicted by Bioelectrical impedance analysis (BIA)* \| Whole-body SMM or ASMM by Magnetic Resonance Imaging (MRI, total body protocoI) \| Shen (2004) [44 [45 [46 [47 [48 [( \| \|	{ "page_id": null, "source": 7345, "title": "from dpo" }
\| Mid-thigh muscle cross-sectional area by Computed Tomography (CT) or MRI \| Lee (2004) [50 [51 [52 \| Goodpaster (2000) [53 [54 [55 [56 [57 \| SPPB \| Short Physical Performance Battery Protocol \| \| \| \| NIH Toolbox \| \| [ \| \| Timed-up-and-go test (TUG) \| TUG \| Mathias (1986) [[40 \| 400-m walk \| Newman (2006) [41. In such cases, further testing for sarcopenia is recommended [( EWGSOP2 recommends use of the SARC-F questionnaire as a way to elicit self-reports from patients on signs that are characteristic of sarcopenia. SARC-F can be readily used in community healthcare and other clinical settings. The SARC-F is a 5-item questionnaire that is self-reported by patients as a screen for sarcopenia risk [( Responses are based on the patient’s perception of his or her limitations in strength, walking ability, rising from a chair, stair	{ "page_id": null, "source": 7345, "title": "from dpo" }
climbing and experiences with falls. This screening tool was evaluated in three large populations—the African American Health Study, Baltimore Longitudinal Study of Aging and the National Health and Nutrition Examination study [( and was likewise used in a study of Chinese men and women [( In these populations, the SARC-F was valid and consistent for identifying people at risk of sarcopenia-associated adverse outcomes. SARC-F has a low-to-moderate sensitivity and a very high specificity to predict low muscle strength [( As such, SARC-F will mostly detect severe cases. We recommend SARC-F as a way to introduce assessment and treatment of sarcopenia into clinical practice. SARC-F is an inexpensive and convenient method for sarcopenia risk screening. A project is underway to translate and validate SARC-F in multiple different world languages [( Since SARC-F is self-reported by the patient, results reflect perceptions of adverse outcomes that matter to the patient. Alternatively, clinicians may prefer a more formal case-finding instrument for use in clinical populations where sarcopenia is likely [( For example, the Ishii screening test is a method that estimates the probability of sarcopenia using an equation-derived score based on three variables—age, grip strength and calf circumference [( #### Measuring sarcopenia parameters ##### Muscle strength Measuring grip strength is simple and inexpensive. Low grip strength is a powerful predictor of poor patient outcomes such as longer hospital stays, increased functional limitations, poor health-related quality of life and death [( ( Accurate measurement of grip strength requires use of a calibrated handheld dynamometer under well-defined test conditions with interpretive data from appropriate reference populations [( Grip strength correlates moderately with strength in other body compartments, so it serves as a reliable surrogate for more complicated measures of arm and leg strength. Because of its ease of use, grip strength is advised for routine use	{ "page_id": null, "source": 7345, "title": "from dpo" }
in hospital practice, in specialty clinical settings, and in community healthcare [28, isometric torque methods can be used to measure lower limb strength [66 can be used as a proxy for strength of leg muscles (quadriceps muscle group). The chair stand test measures the amount of time needed for a patient to rise five times from a seated position without using his or her arms; the timed chair stand test is a variation that counts how many times a patient can rise and sit in the chair over a 30-second interval [64, as Appendicular Skeletal Muscle Mass (ASM), or as muscle cross-sectional area of specific muscle groups or body locations. Magnetic resonance imaging (MRI) and computed tomography (CT) are considered to be gold standards for non-invasive assessment of muscle quantity/mass [64 is a more widely available instrument	{ "page_id": null, "source": 7345, "title": "from dpo" }
to determine muscle quantity (total body lean tissue mass or appendicular skeletal muscle mass) non-invasively, but different DXA instrument brands do not give consistent results [31, weight (ASM/weight) or body mass index (ASM/BMI) [72 [( has been explored for estimation of total or ASM. BIA equipment does not measure muscle mass directly, but instead derives an estimate of muscle mass based on whole-body electrical conductivity. BIA uses a conversion equation that is calibrated with a reference of DXA-measured lean mass in a specific population [( ( BIA equipment is affordable, widely available and portable, especially single-frequency instruments. Since estimates of muscle mass differ when different instrument brands and reference populations are used, we advise use of raw measures produced by the different devices along with the cross-validated Sergi equation for standardisation [( ( BIA prediction models are most relevant to the populations in which they have been derived, and	{ "page_id": null, "source": 7345, "title": "from dpo" }
the Sergi equation is based on older European populations. Age, ethnicity and other related discrepancies between those populations and patients should be considered in the clinic. In addition, BIA measurements can also be influenced by hydration status of the patient. For affordability and portability, BIA-based determinations of muscle mass may be preferable to DXA; however, more study is necessary to validate prediction equations for specific populations [75, weight (ASM/weight) or body mass index (ASM/BMI) [72 [79, and the Timed-Up and Go test (TUG), among other tests. It is not always possible to use certain physical performance measures, such as when a patient’s test performance is impaired by dementia, gait disorder or a balance disorder. Gait speed is considered a quick, safe and highly reliable test for sarcopenia, and it	{ "page_id": null, "source": 7345, "title": "from dpo" }
is widely used in practice [81 can be performed in most clinical settings. In terms of its convenience to use and ability to predict sarcopenia-related outcomes, gait speed is advised by EWGSOP2 for evaluation of physical performance [( The SPPB also predicts outcomes [( but it is more often used in research than in clinical assessment because the battery of tests takes at least 10 min to administer. Likewise, the 400-m walk test predicts mortality but requires a corridor more than 20 m long to set up the testing course [( The TUG has also been found to predict mortality [( ###	{ "page_id": null, "source": 7345, "title": "from dpo" }
Alternative or new tests and tools A variety of methods are being used or evaluated to determine the quantity and quality of muscle and impact of sarcopenia on the patient’s QoL. These diagnostic measures are being tested for validity, reliability and accuracy and may play a relevant role in the future. For use in practice, tools need to be cost-effective, standardised and repeatable by practitioners in a variety of clinical settings and across different patient populations [78 has been used to image tumors and their response to treatment, and this technique has also been shown to give practical and precise measures of body composition. In particular, CT images of a specific lumbar vertebral landmark (L3) correlated significantly with whole-body muscle [94 has also been used in research studies, as it is a good predictor of whole-body skeletal muscle mass and very sensitive to change [( ( ( ( Mid-thigh muscle area is more strongly correlated with total body muscle	{ "page_id": null, "source": 7345, "title": "from dpo" }
volume than are lumbar muscle areas L1–L5 [42 [101 is ingested by a fasting patient; labelled	{ "page_id": null, "source": 7345, "title": "from dpo" }
and unlabelled creatine and creatinine in urine are later measured using liquid chromatography and tandem mass spectrometry [( Total body creatine pool size and muscle mass are calculated from D 3-creatinine enrichment in urine. Creatine dilution test results correlate well with MRI-based measures of muscle mass and modestly with measures from BIA and DXA [( ( The creatine dilution test is mostly used in research at this time, so further refinement is needed to make this methodology practical for use in clinical settings. #### Ultrasound assessment of muscle Ultrasound is a widely used research technique to measure muscle quantity, to identify muscle wasting, and also as a measure of muscle quality. It is reliable and valid and is starting to be used at the bedside by trained clinicians. Ultrasound is accurate with good intra- and inter-observer reliability, even in older subjects [( Assessment of pennate muscles such as the quadriceps femoris can detect a decrease in muscle thickness and cross-sectional area within a relatively short period of time, thus suggesting potential for use of this tool in clinical practice, including use in the community [( ( The use of ultrasound has recently been expanded in clinical practice to support the diagnosis of sarcopenia in older adults. The EuGMS sarcopenia group recently proposed a consensus protocol for using ultrasound in muscle assessment, including measurement of muscle thickness, cross-sectional area, fascicle length, pennation angle and echogenicity [( Echogenicity reflects muscle quality, since non-contractile tissue associated with myosteatosis shows hyper-echogenicity [( ( Thus, ultrasound has the advantage of being able to assess both muscle quantity and quality. A systematic review on the use of ultrasound to assess muscle in this population concluded that the tool was reliable and valid for the assessment of muscle size in older adults, including those with comorbid conditions	{ "page_id": null, "source": 7345, "title": "from dpo" }
such as coronary artery disease, stroke, and chronic obstructive pulmonary disease [( Ultrasound was shown to have good validity to estimate muscle mass as compared to DXA, MRI and CT. While data are available for older adults, more research is needed to validate prediction equations for those with varying health conditions and functional status [( #### Specific biomarkers or panels of biomarkers The development and validation of a single biomarker might be an easy and cost-effective way to diagnose and monitor people with sarcopenia. Potential biomarkers could include markers of the neuromuscular junction, muscle protein turnover, behaviour-mediated pathways, inflammation-mediated pathways, redox-related factors and hormones or other anabolic factors [( However, because of the complex pathophysiology of sarcopenia, it is unlikely that there will be a single biomarker that can identify the condition in the heterogeneous population of young and old people [( The development of a panel of biomarkers must instead be considered, including potential serum markers and tissue markers [( ( The implementation of a multidimensional methodology for the modelling of these pathways could provide a way to stratify risk for sarcopenia, facilitate the identification of a worsening condition and provide monitoring of treatment effectiveness [( #### SarQoL questionnaire From a patient’s perspective, it is important to have sarcopenia treatment plans that address QoL issues. To this end, the SarQoL tool is a self-administered questionnaire for people with sarcopenia [( ( SarQoL identifies and predicts sarcopenia complications that may later impact the patient’s quality of life. SarQoL assists the healthcare provider in assessing a patient’s perception of his or her physical, psychological and social aspects of health. The SarQoL tool has been validated as consistent and reliable, and it can be used in clinical care and in research studies [( The sensitivity of SarQoL to patient status changes over	{ "page_id": null, "source": 7345, "title": "from dpo" }
time needs validation in longitudinal studies. Once validated, SarQoL may serve as a proxy measure of treatment efficacy. To facilitate widespread use of the SarQoL tool, it has been translated into multiple languages. ### Defining cut-off points for sarcopenia tests Cut-off points depend on the measurement technique and on the availability of reference studies and populations. The original EWGSOP consensus paper did not advise specific cut-off points, and disputes over cut-off points have hampered research and development in the field due to lack of study consistency. More recently, the Asian Working Group on Sarcopenia developed an EWGSOP-based consensus that specified cut-off points for diagnostic variables [4 [26 [67 [3 [125 [1 [84 [90 [( \| \| TUG \|	{ "page_id": null, "source": 7345, "title": "from dpo" }
≥20 s \| Bischoff (2003) [127 [128 [26. In clinical practice, EWGSOP2 advises use of the SARC-F questionnaire to find individuals with probable sarcopenia. We advise use of grip strength and chair stand measures to identify low muscle strength. To generate evidence that confirms muscle of low quantity or quality, we recommend evaluation of muscle by DXA and BIA methods in usual clinical care, and by DXA, MRI or	{ "page_id": null, "source": 7345, "title": "from dpo" }
CT in research and in specialty care for individuals at high risk of adverse outcomes. We advise measures of physical performance (SPPB, TUG and 400-m walk tests) to assess severity of sarcopenia. Sarcopenia development ---------------------- ### Time course Muscle mass and strength vary across a lifetime—generally increasing with growth in youth and young adulthood, being maintained in midlife and then decreasing with ageing. In young adulthood (up to ~40 years of age), maximal levels, which are higher in men than in women, are reached (Figure 2 and loss of strength (1.5–5% per year) have been reported [129. Centiles shown are 10th, 25th, 50th, 75th and 90th. Cut-off points based on _T_-score of ≤ -2.5 are shown for males and females (≤27 kg and 16 kg, respectively). Color-coding represents different birth cohorts used for the study (Figure adapted with permission from R Dodds and PLOS One). Interestingly, there is a positive association between birth weight and muscle strength, which is maintained across the life course [( In the initial stages of sarcopenia development, an individual may be above the threshold of low physical performance and is very likely to be above the threshold of disability. While genetic and lifestyle factors can hasten muscle weakening and progression toward functional impairment and disability, interventions including nutrition and exercise training seem to slow or reverse these processes [( Therefore, to prevent or delay sarcopenia, the aim is to maximise muscle in youth and young adulthood, maintain muscle in middle age and minimise loss in older age (Figure ( [(	{ "page_id": null, "source": 7345, "title": "from dpo" }
#### Figure 3. ![Image 3: Figure 3. when no other specific cause is evident, while sarcopenia is considered ‘secondary’ when causal factors other than (or in addition to) ageing are evident. Sarcopenia can occur secondary to a systemic disease, especially one that may invoke inflammatory processes, e.g. malignancy or organ failure. Physical inactivity also contributes to development of sarcopenia, whether due to a sedentary lifestyle or to disease-related immobility or disability [132 and secondary (disease, inactivity, and poor nutrition). Because a wide range of factors contribute to sarcopenia development, numerous muscle changes seem possible when these multiple factors interact. ### Acute and chronic sarcopenia EWGSOP2 newly identifies subcategories of sarcopenia as acute and chronic. Sarcopenia that has lasted less than 6 months is considered an acute condition, while sarcopenia lasting ≥6 months is considered a chronic condition. Acute sarcopenia is usually related to an acute illness or injury, while chronic sarcopenia is likely to be associated with chronic and progressive conditions and increases the	{ "page_id": null, "source": 7345, "title": "from dpo" }
risk of mortality. This distinction is intended to underscore the need to conduct periodic sarcopenia assessments in individuals who may be at risk for sarcopenia in order to determine how quickly the condition is developing or worsening. Such observations are expected to facilitate early intervention with treatments that can help prevent or delay sarcopenia progression and poor outcomes. ### Sarcopenic obesity Sarcopenic obesity is a condition of reduced lean body mass in the context of excess adiposity [( Sarcopenic obesity is most often reported in older people, as both risk and prevalence increase with age [( Obesity exacerbates sarcopenia, increases the infiltration of fat into muscle, lowers physical function and increases risk of mortality [( Sarcopenic obesity is a distinct condition, and there are ongoing initiatives to improve its definition. Sarcopenic obesity is therefore outside of the scope of this article. ### Frailty Frailty is a multidimensional geriatric syndrome that is characterised by cumulative decline in multiple body systems or functions [( ( with pathogenesis involving physical as well as social dimensions [( Frailty increases vulnerability to poor health outcomes such as disability, hospital admission, reduced quality of life and even death [( ( The physical phenotype of frailty, described by Fried and co-workers [( shows significant overlap with sarcopenia; low grip strength and slow gait speed are characteristic of both. Weight loss, another diagnostic criterion for frailty, is also a major etiologic factor for sarcopenia. Treatment options for physical frailty and for sarcopenia likewise overlap—provision of optimal protein intake, supplementation of vitamin D, and physical exercise [( ( ( Taken together, frailty and sarcopenia are still distinct—one a geriatric syndrome and the other a disease. While sarcopenia is a contributor to the development of physical frailty, the syndrome of frailty represents a much broader concept. Frailty is seen as	{ "page_id": null, "source": 7345, "title": "from dpo" }
the decline over a lifetime in multiple physiological systems, resulting in negative consequences to physical, cognitive, and social dimensions. Frailty’s diagnostic tools reflect these multiple dimensions, e.g. the Groningen Frailty Indicator, the Frailty Index of Rockwood _et al._ and others [146, reduced nutrient bioavailability (e.g. with diarrhea, vomiting) or high nutrient requirements (e.g. with inflammatory diseases such as cancer or organ failure with cachexia) [150, studies are needed to establish if gender-specific and region-specific threshold values for sarcopenia diagnosis improve prediction of outcomes. * What muscle quality indicators best predict outcomes? How can we best assess muscle quality? What tools and measurements are accurate and affordable? * What are the kinetics of muscle loss	{ "page_id": null, "source": 7345, "title": "from dpo" }
in different people and circumstances, as detected by multiple measurements? What are differences in causes and consequences of gradual versus rapid loss? * What outcomes are best used as sensitive measures of response to sarcopenia treatments? Summary and call-to-action -------------------------- Sarcopenia, i.e. muscle failure, is a muscle disease rooted in adverse muscle changes that accrue across a lifetime; sarcopenia is common among adults of older age but can also occur earlier in life. Sarcopenia is defined by low levels of measures for three parameters: (1) muscle strength, (2) muscle quantity/quality and (3) physical performance as an indicator of severity. Although research findings over the last decade have answered many questions, other findings raised more areas for researchers to address in the future. Thus, a clear definition of sarcopenia, as well as clear diagnostic criteria, are necessary to guide both clinical practice and research design for the future. For screening and diagnosis of sarcopenia, EWGSOP recommends following the pathway: Find cases-Assess-Confirm-Severity (F-A-C-S). Find-cases: To identify individuals at risk for sarcopenia, EWGSOP advises use of the SARC-F questionnaire or clinical suspicion to find sarcopenia-associated symptoms. Assess: To assess for evidence of sarcopenia, EWGSOP recommends use of grip strength or a chair stand measure with specific cut-off-points for each test. For special cases and for research studies, other methods for measurement of strength (knee flexion/extension) can be used. Confirm: To confirm sarcopenia by detection of low muscle quantity and quality, DXA is advised in clinical practice, and DXA, BIA, CT or MRI in research studies. Determine Severity: Severity can be evaluated by performance measures; gait speed, SPPB, TUG and 400-m walk tests can be used. EWGSOP2's updated recommendations aim to increase awareness of sarcopenia and its risk. With these new recommendations, EWGSOP2 calls for healthcare professionals who treat patients at risk for sarcopenia	{ "page_id": null, "source": 7345, "title": "from dpo" }
to take actions that will promote early detection and treatment. We also encourage more research in the field of sarcopenia in order to prevent or delay adverse outcomes that also incur a heavy burden for patients and healthcare systems. ### Key points. * In the updated definition of sarcopenia, EWGSOP2 elevates low strength to the forefront as a primary indicator of probable sarcopenia. * Sarcopenia is now defined as a muscle disease that may be acute or chronic. * We recommend an algorithm for case-finding, diagnosis, and severity determination for systematic and consistent identification of people with sarcopenia or its risk. * We recommend simple, specific cut-off points for measures that identify and characterize sarcopenia. * These new recommendations are aimed at facilitating early detection and better treatment of sarcopenia in clinical practice. Acknowledgements ---------------- The authors warmly thank Cecilia Hofmann, PhD, (C Hofmann & Associates, Western Springs, IL USA) for her valuable assistance in compilation of the medical literature, for thorough editing of this multi-authored manuscript, and for her longstanding association with the EWGSOP. Extended Group for EWGSOP2 includes: Ivan Bautmans (Department of Gerontology and Department of Frailty in Ageing, Vrije University Brussel; Brussels, Belgium); Jean-Pierre Baeyens (Geriatrician at the Teaching Hospital AZ Alma; Eeklo, Belgium; and University of Luxembourg; Luxembourg City, Luxenbourg); Matteo Cesari (Geriatric Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Università di Milano; Milan, Italy); Antonio Cherubini (Geriatria, Accettazione geriatrica e Centro di ricerca per l’invecchiamento, IRCCS INRCA, Ancona, Italy); John Kanis(Center for Metabolic Bone Diseases, University of Sheffield Medical School; Sheffield, UK and Institute for Health and Ageing, Australian Catholic University; Melbourne, Australia); Marcello Maggio (Geriatric Clinic Unit, Geriatric Rehabilitation Department, University-Hospital of Parma, Department of Medicine and Surgery); Finbarr Martin (Department of Ageing and Health, Guys and St Thomas’ NHS Foundation Trust; London,	{ "page_id": null, "source": 7345, "title": "from dpo" }
UK); Jean-Pierre Michel(Department of Rehabilitation and Geriatrics, University of Geneva; Geneva, Switzerland); Kaisu Pitkala (Department of General Practice and Primary Health Care, University of Helsinki and Helsinki University Central Hospital, Unit of Primary Health Care; Helsinki, Finland); Jean-Yves Reginster (Bone and Cartilage Metabolism Unit, University of Liège; Liège, Belgium); René Rizzoli (Department of Bone Disease, University of Geneva; Geneva, Switzerland); Dolores Sánchez-Rodríguez (Geriatrics Department, Parc Salut Mar. Rehabilitation Research Group, Institut Hospital del Mar d’Investigacions Mèdiques (IMIM). Universitat Autònoma de Barcelona, Universitat Pompeu Fabra; Barcelona, Spain); Jos Schols (Department of Health Services Research, Maastricht University; Maastricht, the Netherlands). Contributor Information ----------------------- Writing Group for the European Working Group on Sarcopenia in Older People 2 (EWGSOP2), and the Extended Group for EWGSOP2: [Ivan Bautmans]( [Jean-Pierre Baeyens]( [Matteo Cesari]( [Antonio Cherubini]( [John Kanis]( [Marcello Maggio]( [Finbarr Martin]( [Jean-Pierre Michel]( [Kaisu Pitkala]( [Jean-Yves Reginster]( [René Rizzoli]( [Dolores Sánchez-Rodríguez]( and [Jos Schols]( Conflict of interest -------------------- O Bruyére has received grants or consulting fees from Biophytis, IBSA, Servier, SMB, TRB Chemedica and UCB; he is also a shareholder for SarQoL sprl, a spin-off of the University of Liege. T. Cederholm has received unconditional research grants from Nestlé, Nutricia and Fresenius Kabi, and is giving lectures arranged by Nestlé, Nutricia, Fresenius Kabi and Abbott. A. Cherubini is giving presentations for and is consulting with Nestle. C Cooper has received lecture fees and honoraria from Amgen, Danone, Eli Lilly, GSK, Medtronic, Merck, Nestlé, Novartis, Pfizer, Roche, Servier, Shire, Takeda and UCB. A. Cruz-Jentoft has received speakers fees from Abbott Nutrition, Fresenius, Nestlé, Nutricia, Sanofi-Aventis; is a member of advisory boards for Abbott Nutrition, Boehringer Ingelheim Pharma, Nestlé, Pfizer and Regeneron; and has worked on research projects with Novartis, Nutricia, and Regeneron. J.-P. Michel is a speaker for Abbott Nutrition, and serves as a vaccine consultant to	{ "page_id": null, "source": 7345, "title": "from dpo" }
Pfizer and Merck. Y. Rolland is a consultant for Lactalis, Nestlé, Baxter, Novartis, and Biophytis. S Schneider reports honoraria from B. Braun, Fresenius Kabi, Grand-Fontaine, and Nestlé; he has also received honoraria and a grant from Nutricia. C.C. Sieber has received fees for presentations for and consulting with Abbott, Braun, Danone, Fresenius, Nestle, Nutricia, AMGEN, Berlin-Chemie, MSD, Novartis, Roche, Sevier and Vifor. M. Vandewoude is a lecturer for Nutricia. The following authors declare ‘none’ for potential conflicts of interest: J.P. Baeyens, G. Bahat, J. Bauer, I. Bautmans, Y. Boirie, M. Cesari, J.A. Kanis, F. Landi, M. Maggio, F.C. Martin, K. Pitkälä, J.-Y. Reginster, R. Rizzoli, D. Sánchez-Rodriguez, A.A. Sayer, J. Schols, E. Topinkova, M. Visser and M. Zamboni. Funding ------- The EuGMS received a grant from Abbott to fund the European Working Group on Sarcopenia in Older People 2 (EWGSOP2). This grant was used for operational activities of the EuGMS and for funding the two meetings of the Working Group. Abbott had no role in the choice of members of the group, but had the right to have observers at the meetings. Members of the Working Group received no salary or other incomes from the EuGMS, Abbott or any other organisation for any of the tasks involved in the preparation of this manuscript or for attending the meetings of the group. Abbott played no role in the preparation or approval of this manuscript. References ---------- * 1. Cruz-Jentoft AJ, Baeyens JP, Bauer JM et al. Sarcopenia: European consensus on definition and diagnosis: report of the European working group on sarcopenia in older people. Age Ageing 2010; 39: 412–23. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 2. Morley JE, Abbatecola AM, Argiles JM et al. Sarcopenia with limited mobility: an international consensus. J Am Med Dir Assoc 2011; 12: 403–9.	{ "page_id": null, "source": 7345, "title": "from dpo" }
[[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 3. Studenski SA, Peters KW, Alley DE et al. The FNIH sarcopenia project: rationale, study description, conference recommendations, and final estimates. J Gerontol A Biol Sci Med Sci 2014; 69: 547–58. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 4. Chen LK, Liu LK, Woo J et al. Sarcopenia in Asia: consensus report of the Asian working group for sarcopenia. J Am Med Dir Assoc 2014; 15: 95–101. [[DOI]( [[PubMed]( [[Google Scholar]( * 5. Argiles JM, Campos N, Lopez-Pedrosa JM et al. Skeletal muscle regulates metabolism via interorgan crosstalk: roles in health and disease. J Am Med Dir Assoc 2016; 17: 789–96. [[DOI]( [[PubMed]( [[Google Scholar]( * 6. Frontera WR, Ochala J. Skeletal muscle: a brief review of structure and function. Calcif Tissue Int 2015; 96: 183–95. [[DOI]( [[PubMed]( [[Google Scholar]( * 7.[ ICD-10-CM Diagnosis Code M62.84_. 2018. [cited 2018 March 12]. * 8. Vellas B, Fielding RA, Bens C et al. Implications of ICD-10 for sarcopenia clinical practice and clinical trials: report by the International Conference on Frailty and Sarcopenia Research Task Force. J Frailty Aging 2018; 7: 2–9. [[DOI]( [[PubMed]( [[Google Scholar]( * 9. Mijnarends DM, Luiking YC, Halfens RJG et al. Muscle, health and costs: a glance at their relationship. J Nutr Health Aging 2018; 22: 766–73. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 10. Bischoff-Ferrari HA, Orav JE, Kanis JA et al. Comparative performance of current definitions of sarcopenia against the prospective incidence of falls among community-dwelling seniors age 65 and older. Osteoporos Int 2015; 26: 2793–802. [[DOI]( [[PubMed]( [[Google Scholar]( * 11. Schaap LA, van Schoor NM, Lips P et al. Associations of sarcopenia definitions, and their components, with the incidence of recurrent falling and fractures: the longitudinal aging study Amsterdam. J Gerontol A Biol Sci	{ "page_id": null, "source": 7345, "title": "from dpo" }
Med Sci 2018; 73: 1199–204. [DOI, a specific health-related quality of life questionnaire for Sarcopenia. J Cachexia Sarcopenia Muscle 2017; 8: 238–44. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 17. Dos Santos L, Cyrino ES, Antunes M et al. Sarcopenia and physical independence in older adults: the independent and synergic role of muscle mass and muscle function. J Cachexia Sarcopenia Muscle 2017; 8: 245–50. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 18. Akune T, Muraki S, Oka H et al. Incidence of certified need of care in the long-term care insurance system and its risk factors in the elderly of Japanese population-based cohorts: the ROAD study. Geriatr Gerontol Int 2014; 14: 695–701. [[DOI]( [[PubMed]( [[Google Scholar]( * 19. Steffl M, Bohannon RW, Sontakova L et al. Relationship between sarcopenia and physical activity in older people: a systematic review and meta-analysis. Clin Interv Aging 2017; 12: 835–45. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 20. De Buyser	{ "page_id": null, "source": 7345, "title": "from dpo" }
SL, Petrovic M, Taes YE et al. Validation of the FNIH sarcopenia criteria and SOF frailty index as predictors of long-term mortality in ambulatory older men. Age Ageing 2016; 45: 602–8. [DOI. Clin Interv Aging 2017; 12: 2003–07. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 24. Sousa AS, Guerra RS, Fonseca I et al. Financial impact of sarcopenia on hospitalization costs. Eur J Clin Nutr 2016; 70: 1046–51. [[DOI]( [[PubMed]( [[Google Scholar]( * 25. Sayer AA, Syddall H, Martin H et al. The developmental origins of sarcopenia. J Nutr Health Aging 2008; 12: 427–32. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 26. Dodds RM, Syddall HE, Cooper R et al. Grip strength across the life course: normative data from twelve British studies. PLoS One 2014; 9: e113637. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 27. Sayer AA, Syddall HE, Gilbody HJ et al. Does sarcopenia originate in early life? Findings from the Hertfordshire cohort study. J Gerontol A Biol Sci Med Sci 2004; 59: M930–4. [[DOI]( [[PubMed]( [[Google Scholar]( * 28. Ibrahim K, May C, Patel HP et	{ "page_id": null, "source": 7345, "title": "from dpo" }
al. A feasibility study of implementing grip strength measurement into routine hospital practice (GRImP): study protocol. Pilot Feasibility Stud 2016; 2: 27. [DOI study. Lancet 2015; 386: 266–73. [DOI and bio-impedance analysis (BIA) for the evaluation of sarcopenia by Belgian and Latin American geriatricians. J Cachexia Sarcopenia Muscle 2014; 5: 79–81. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 35. Keller K. Sarcopenia. Wien Med Wochenschr 2018. 10.1007/s10354-018-0618-2 [Epub ahead of print]. [[DOI]( [[PubMed]( [[Google Scholar]( * 36. Han A, Bokshan SL, Marcaccio SE et al. Diagnostic criteria and clinical outcomes in sarcopenia research:	{ "page_id": null, "source": 7345, "title": "from dpo" }
a literature review. J Clin Med 2018; 7 10.3390/jcm7040070. [DOI: 93–101. [DOI 1998; 85: 115–22. [[DOI]( [[PubMed]( [[Google Scholar]( * 44. Shen W, Punyanitya M, Wang Z et al. Total body skeletal muscle and adipose tissue volumes: estimation from a single abdominal cross-sectional image. J Appl	{ "page_id": null, "source": 7345, "title": "from dpo" }
Physiol (1985) 2004; 97: 2333–8. [[DOI]( [[PubMed]( [[Google Scholar]( * 45. Sergi G, De Rui M, Stubbs B et al. Measurement of lean body mass using bioelectrical impedance analysis: a consideration of the pros and cons. Aging Clin Exp Res 2017; 29: 591–97. [[DOI]( [[PubMed]( [[Google Scholar]( * 46. Maden-Wilkinson TM, Degens H, Jones DA et al. Comparison of MRI and DXA to measure muscle size and age-related atrophy in thigh muscles. J Musculoskelet Neuronal Interact 2013; 13: 320–8. [[PubMed]( [[Google Scholar]( * 47. Heymsfield SB, Smith R, Aulet M et al. Appendicular skeletal muscle mass: measurement by dual-photon absorptiometry. Am J Clin Nutr 1990; 52: 214–8. [[DOI]( [[PubMed]( [[Google Scholar]( * 48. Kim J, Wang Z, Heymsfield SB et al. Total-body skeletal muscle mass: estimation by a new dual-energy X-ray absorptiometry method. Am J Clin Nutr 2002; 76: 378–83. [[DOI]( [[PubMed]( [[Google Scholar]( * 49. Yamada Y, Nishizawa M, Uchiyama T et al. Developing and validating an age-independent equation using multi-frequency bioelectrical impedance analysis for estimation of appendicular skeletal muscle mass and establishing a cutoff for sarcopenia. Int J Environ Res Public Health 2017; 14 10.3390/ijerph14070809. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 50. Lee SJ, Janssen I, Heymsfield SB et al. Relation between whole-body and regional measures of human skeletal muscle. Am J Clin Nutr 2004; 80: 1215–21. [[DOI]( [[PubMed]( [[Google Scholar]( * 51. van der Werf A, Langius JAE, de van der Schueren MAE et al. Percentiles for skeletal muscle index, area and radiation attenuation based on computed tomography imaging in a healthy Caucasian population. Eur J Clin Nutr 2018; 72: 288–96. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 52. Derstine BA, Holcombe SA, Ross BE et al. Skeletal muscle cutoff values for sarcopenia diagnosis using T10 to L5 measurements in a healthy US population.	{ "page_id": null, "source": 7345, "title": "from dpo" }
Sci Rep 2018; 8: 11369. [DOI 2000; 89: 104–10. [DOI-Reykjavik study. Am J Epidemiol 2016; 183: 53–60. [DOI 2007; 102: 748–54. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 58. Woo J, Leung J, Morley JE. Defining sarcopenia in terms of incident adverse outcomes. J Am Med Dir Assoc 2015; 16: 247–52. [[DOI]( [[PubMed]( [[Google Scholar]( * 59. Bahat G, Yilmazi O, Kilic C et al. Performance of SARC-F in regard to sarcopenia definitions, muscle mass and functional measures. J Nutr Health Aging 2018. 10.1007/s12603-018-1067-8; Epub ahead of print. [[DOI]( [[PubMed]( [[Google Scholar]( * 60. Bahat G, Yilmaz O, Oren M et al. Cross-cultural adaptation and validation of the SARC-F to assess sarcopenia: methodological report from European Union Geriatric Medicine Society Sarcopenia Special Interest Group. Eur Geriatr Med 2018;	{ "page_id": null, "source": 7345, "title": "from dpo" }
9: 23–8. [[DOI]( [[PubMed]( [[Google Scholar]( * 61. Locquet M, Beaudart C, Reginster JY et al. Comparison of the performance of five screening methods for sarcopenia. Clin Epidemiol 2018; 10: 71–82. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 62. Rossi AP, Fantin F, Micciolo R et al. Identifying sarcopenia in acute care setting patients. J Am Med Dir Assoc 2014; 15: 303.e7–12. [[DOI]( [[PubMed]( [[Google Scholar]( * 63. Steiber N. Strong or weak handgrip? Normative reference values for the German population across the life course stratified by sex, age, and body height. PLoS One 2016; 11: e0163917. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 64. Beaudart C, McCloskey E, Bruyere O et al. Sarcopenia in daily practice: assessment and management. BMC Geriatr 2016; 16: 170. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 65. Sipers WM, Verdijk LB, Sipers SJ et al. The Martin vigorimeter represents a reliable and more practical tool than the Jamar dynamometer to assess handgrip strength in the geriatric patient. J Am Med Dir Assoc 2016; 17: 466.e1–7. [[DOI]( [[PubMed]( [[Google Scholar]( * 66. Francis P, Toomey C, Mc Cormack W et al. Measurement of maximal isometric torque and muscle quality of the knee extensors and flexors in healthy 50- to 70-year-old women. Clin Physiol Funct Imaging 2017; 37: 448–55. [[DOI]( [[PubMed]( [[Google Scholar]( * 67. Cesari M, Kritchevsky SB, Newman AB et al. Added value of physical performance measures in predicting adverse health-related events: results from the Health, Aging And Body Composition Study. J Am Geriatr Soc 2009; 57: 251–9. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 68. Jones CJ, Rikli RE, Beam WC. A 30-s chair-stand test as a measure of lower body strength in community-residing older adults. Res Q Exerc Sport 1999; 70: 113–9. [[DOI]( [[PubMed]( [[Google Scholar]( * 69.	{ "page_id": null, "source": 7345, "title": "from dpo" }
Cooper C, Fielding R, Visser M et al. Tools in the assessment of sarcopenia. Calcif Tissue Int 2013; 93: 201–10. [DOI. Clin Nutr 2003; 22: 537–43. [[DOI]( [[PubMed]( [[Google Scholar]( * 74. Sergi G, De Rui M, Veronese N et al. Assessing appendicular skeletal muscle mass with bioelectrical impedance analysis in free-living Caucasian older adults. Clin Nutr 2015; 34: 667–73. [[DOI]( [[PubMed]( [[Google Scholar]( * 75. Gonzalez MC, Heymsfield SB. Bioelectrical impedance analysis for diagnosing sarcopenia and cachexia: what are we really estimating? J Cachexia Sarcopenia Muscle 2017; 8: 187–89. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 76. Yu SC, Powell A, Khow KS et al. The performance of five bioelectrical impedance analysis prediction equations against dual X-ray absorptiometry in estimating appendicular skeletal muscle mass in an Adult Australian Population. Nutrients 2016; 8: 189. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 77. Reiss J, Iglseder B, Kreutzer M et al. Case finding	{ "page_id": null, "source": 7345, "title": "from dpo" }
for sarcopenia in geriatric inpatients: performance of bioimpedance analysis in comparison to dual X-ray absorptiometry. BMC Geriatr 2016; 16: 52. [DOI Task Force. J Nutr Health Aging 2009; 13: 881–9. [[DOI]( [[PubMed]( [[Google Scholar]( * 83. Peel NM, Kuys SS, Klein K. Gait speed as a measure in geriatric assessment in clinical settings: a systematic review. J Gerontol A Biol Sci Med Sci 2013; 68: 39–46. [[DOI]( [[PubMed]( [[Google Scholar]( * 84. Studenski S, Perera S, Patel K et al. Gait speed and survival in older adults. JAMA 2011; 305: 50–8. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 85. Guralnik JM, Ferrucci L, Pieper CF et al. Lower extremity function and subsequent disability: consistency across studies, predictive models, and value of gait speed alone compared with the short physical performance battery. J Gerontol A	{ "page_id": null, "source": 7345, "title": "from dpo" }
Biol Sci Med Sci 2000; 55: M221–31. [[DOI]( [[PubMed]( [[Google Scholar]( * 86. Maggio M, Ceda GP, Ticinesi A et al. Instrumental and non-instrumental evaluation of 4-meter walking speed in older individuals. PLoS One 2016; 11: e0153583. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 87. Rydwik E, Bergland A, Forsen L et al. Investigation into the reliability and validity of the measurement of elderly people’s clinical walking speed: a systematic review. Physiother Theory Pract 2012; 28: 238–56. [[DOI]( [[PubMed]( [[Google Scholar]( * 88.[ Physical Performance Battery_. [cited 2018 March 19]. * 89. Podsiadlo D, Richardson S. The timed ‘Up & Go’: a test of basic functional mobility for frail elderly persons. J Am Geriatr Soc 1991; 39: 142–8. [[DOI]( [[PubMed]( [[Google Scholar]( * 90. Pavasini R, Guralnik J, Brown JC et al. Short physical performance battery and all-cause mortality: systematic review and meta-analysis. BMC Med 2016; 14: 215. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 91. Vestergaard S, Patel KV, Bandinelli S et al. Characteristics of 400-meter walk test performance and subsequent mortality in older adults. Rejuvenation Res 2009; 12: 177–84. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 92. Bergland A, Jorgensen L, Emaus N et al. Mobility as a predictor of all-cause mortality in older men and women: 11.8 year follow-up in the Tromso study. BMC Health Serv Res 2017; 17: 22. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 93. Heymsfield SB, Gonzalez MC, Lu J et al. Skeletal muscle mass and quality: evolution of modern measurement concepts in the context of sarcopenia. Proc Nutr Soc 2015; 74: 355–66. [[DOI]( [[PubMed]( [[Google Scholar]( * 94. Mourtzakis M, Prado CM, Lieffers JR et al. A practical and precise approach to quantification of body composition in cancer patients using computed tomography images acquired during routine care. Appl	{ "page_id": null, "source": 7345, "title": "from dpo" }
Physiol Nutr Metab 2008; 33: 997–1006. [[DOI]( [[PubMed]( [[Google Scholar]( * 95. Fearon K, Strasser F, Anker SD et al. Definition and classification of cancer cachexia: an international consensus. Lancet Oncol 2011; 12: 489–95. [[DOI]( [[PubMed]( [[Google Scholar]( * 96. Kim EY, Kim YS, Park I et al. Prognostic significance of CT-determined sarcopenia in patients with small-cell lung cancer. J Thorac Oncol 2015; 10: 1795–9. [[DOI]( [[PubMed]( [[Google Scholar]( * 97. Baracos V, Kazemi-Bajestani SM. Clinical outcomes related to muscle mass in humans with cancer and catabolic illnesses. Int J Biochem Cell Biol 2013; 45: 2302–8. [[DOI]( [[PubMed]( [[Google Scholar]( * 98. Moisey LL, Mourtzakis M, Cotton BA et al. Skeletal muscle predicts ventilator-free days, ICU-free days, and mortality in elderly ICU patients. Crit Care 2013; 17: R206. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 99. Montano-Loza AJ, Meza-Junco J, Baracos VE et al. Severe muscle depletion predicts postoperative length of stay but is not associated with survival after liver transplantation. Liver Transpl 2014; 20: 640–8. [[DOI]( [[PubMed]( [[Google Scholar]( * 100. Baracos VE, Reiman T, Mourtzakis M et al. Body composition in patients with non-small cell lung cancer: a contemporary view of cancer cachexia with the use of computed tomography image analysis. Am J Clin Nutr 2010; 91: 1133S–37S. [[DOI]( [[PubMed]( [[Google Scholar]( * 101. Gu DH, Kim MY, Seo YS et al. Clinical usefulness of psoas muscle thickness for the diagnosis of sarcopenia in patients with liver cirrhosis. Clin Mol Hepatol 2018; 24: 319–30. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 102. Hanaoka M, Yasuno M, Ishiguro M et al. Morphologic change of the psoas muscle as a surrogate marker of sarcopenia and predictor of complications after colorectal cancer surgery. Int J Colorectal Dis 2017; 32: 847–56. [[DOI]( [[PubMed]( [[Google Scholar]( * 103. Baracos VE. Psoas	{ "page_id": null, "source": 7345, "title": "from dpo" }
as a sentinel muscle for sarcopenia: a flawed premise. J Cachexia Sarcopenia Muscle 2017; 8: 527–28. [DOI 1999; 86: 188–94. [DOI 1999; 86: 195–201. [DOI dilution in urine for estimation of total body skeletal muscle mass: accuracy and variability vs. MRI and DXA. J Appl Physiol 2018; 124: 1–9. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar](	{ "page_id": null, "source": 7345, "title": "from dpo" }
* 111. Buehring B, Siglinsky E, Krueger D et al. Comparison of muscle/lean mass measurement methods: correlation with functional and biochemical testing. Osteoporos Int 2018; 29: 675–83. [[DOI]( [[PubMed]( [[Google Scholar]( * 112. Galindo Martin CA, Monares Zepeda E, Lescas Mendez OA. Bedside ultrasound measurement of rectus femoris: a tutorial for the nutrition support clinician. J Nutr Metab 2017; 2017: 2767232. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 113. Ticinesi A, Narici MV, Lauretani F et al. Assessing sarcopenia with vastus lateralis muscle ultrasound: an operative protocol. Aging Clin Exp Res 2018. 10.1007/s40520-018-0958-1 [Epub ahead of print]. [[DOI]( [[PubMed]( [[Google Scholar]( * 114. SARCUS working group on behalf of the Sarcopenia Special Interest Group of the European Geriatric Medicine Society Perkisas S, Baudry S et al. Application of ultrasound for muscle assessment in sarcopenia: towards standardized measurements. Eur J Med 2018. In press. 10.1007/s41999-018-0104-9. [[DOI]( [[PubMed]( [[Google Scholar]( * 115. Sipila S, Suominen H. Muscle ultrasonography and computed tomography in elderly trained and untrained women. Muscle Nerve 1993; 16: 294–300. [[DOI]( [[PubMed]( [[Google Scholar]( * 116. Ismail C, Zabal J, Hernandez HJ et al. Diagnostic ultrasound estimates of muscle mass and muscle quality discriminate between women with and without sarcopenia. Front Physiol 2015; 6: 302. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 117. Nijholt W, Scafoglieri A, Jager-Wittenaar H et al. The reliability and validity of ultrasound to quantify muscles in older adults: a systematic review. J Cachexia Sarcopenia Muscle 2017; 8: 702–12. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 118. Ticinesi A, Meschi T, Narici MV et al. Muscle ultrasound and sarcopenia in older individuals: a clinical perspective. J Am Med Dir Assoc 2017; 18: 290–300. [[DOI]( [[PubMed]( [[Google Scholar]( * 119. Abe T, Loenneke JP, Young KC et al. Validity of ultrasound prediction equations for	{ "page_id": null, "source": 7345, "title": "from dpo" }
total and regional muscularity in middle-aged and older men and women. Ultrasound Med Biol 2015; 41: 557–64. [DOI: a health-related quality of life questionnaire specific to sarcopenia. Expert Rev Pharmacoecon Outcomes Res 2017; 17: 335–41. [DOI: impact of the use of different diagnosis definitions. Aging Clin Exp Res 2018; 30: 307–13. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 125. Gould H, Brennan SL, Kotowicz MA et al. Total and appendicular lean mass reference ranges for Australian men and women: the Geelong osteoporosis study. Calcif Tissue Int 2014; 94: 363–72. [[DOI]( [[PubMed]( [[Google Scholar]( * 126. Guralnik JM, Ferrucci L, Simonsick EM et al. Lower-extremity function in persons over the age of 70 years as a predictor of subsequent disability. N Engl J Med 1995; 332: 556–61. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 127. Bischoff HA, Stahelin HB, Monsch AU et al. Identifying a cut-off point for normal mobility: a comparison of the timed ‘up and go’ test in community-dwelling and institutionalised elderly women. Age Ageing 2003; 32: 315–20.	{ "page_id": null, "source": 7345, "title": "from dpo" }
[[DOI]( [[PubMed]( [[Google Scholar]( * 128. Newman AB, Simonsick EM, Naydeck BL et al. Association of long-distance corridor walk performance with mortality, cardiovascular disease, mobility limitation, and disability. JAMA 2006; 295: 2018–26. [[DOI]( [[PubMed]( [[Google Scholar]( * 129. Keller K, Engelhardt M. Strength and muscle mass loss with aging process. Age and strength loss. Muscles Ligaments Tendons J 2013; 3: 346–50. [[PMC free article]( [[PubMed]( [[Google Scholar]( * 130. Dodds R, Denison HJ, Ntani G et al. Birth weight and muscle strength: a systematic review and meta-analysis. J Nutr Health Aging 2012; 16: 609–15. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 131. Bloom I, Shand C, Cooper C et al. Diet quality and sarcopenia in older adults: a systematic review. Nutrients 2018; 10. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 132. Mijnarends DM, Koster A, Schols JM et al. Physical activity and incidence of sarcopenia: the population-based AGES-Reykjavik Study. Age Ageing 2016; 45: 614–20. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 133. Prado CM, Wells JC, Smith SR et al. Sarcopenic obesity: a critical appraisal of the current evidence. Clin Nutr 2012; 31: 583–601. [[DOI]( [[PubMed]( [[Google Scholar]( * 134. Johnson Stoklossa CA, Sharma AM, Forhan M et al. Prevalence of sarcopenic obesity in adults with class II/III obesity using different diagnostic criteria. J Nutr Metab 2017; 2017: 7307618. [[DOI]( [[PMC free article]( [[PubMed]( [[Google Scholar]( * 135. Kalinkovich A, Livshits G. Sarcopenic obesity or obese sarcopenia: A cross talk between age-associated adipose tissue and skeletal muscle inflammation as a main mechanism of the pathogenesis. Ageing Res Rev 2017; 35: 200–21. [[DOI]( [[PubMed]( [[Google Scholar]( * 136. Barbat-Artigas S, Pion CH, Leduc-Gaudet JP et al. Exploring the role of muscle mass, obesity, and age in the relationship between muscle quality and physical function. J Am Med Dir	{ "page_id": null, "source": 7345, "title": "from dpo" }
Assoc 2014; 15: 303.e13–20. [DOI 2015; 15(Suppl 6): s88–91. [DOI. Gerontologist 2001; 41: 236–37. [[Google Scholar]( * 147. Rockwood K, Song X, MacKnight C	{ "page_id": null, "source": 7345, "title": "from dpo" }
et al. A global clinical measure of fitness and frailty in elderly people. CMAJ 2005; 173: 489–95. [DOI ‘cachexia-anorexia in chronic wasting diseases’ and ‘nutrition in geriatrics’. Clin Nutr 2010; 29: 154–9. [[DOI]( [[PubMed]( [[Google Scholar]( * 151. Cederholm T, Barazzoni R, Austin P et al. ESPEN guidelines on definitions and terminology of clinical nutrition. Clin Nutr 2017; 36: 49–64. [[DOI]( [[PubMed]( [[Google Scholar]( * 152. Cederholm T, Jensen GL, Correia M et al. GLIM criteria for the diagnosis of malnutrition - A consensus report from the global clinical nutrition community. Clin Nutr 2018. 10.1002/jpen.1440 [Epub ahead of print]. [[DOI]( [[PubMed]( [[Google Scholar](	{ "page_id": null, "source": 7345, "title": "from dpo" }
Title: Transportation Research Circulars \| Publications URL Source: Markdown Content: Committee reports, including interim research findings and research problem statements, considered to be of immediate interest but not necessarily of permanent reference value. Transportation Research Circular E-C302 May 07, 2025 Transportation Research Circular E-C302: 2nd Conference on Advancing Transportation Equity , from the Transportation Research Board, summarizes the presentations and discussions from this event held July 15–18, 2024, in Baltimore, Maryland. Transportation Research Circular E-C301 May 16, 2025 Access Management is defined as “the coordinated planning, regulation, and design of access between roadways and land development.” Transportation Research Circular E-C301: Access Management Safety and Design from the Curb to the Interchange for All Users contains extended abstracts from selected presentations presented at the Transportation Research Board 4th International/13th National Conferenc... Transportation Research Circular E-C300 March 21, 2025 Asphalt mix design has always been considered a balance of rutting resistance and durability. The conventional Superpave mix design system targets 4% air voids during design and is referred to in this circular as Superpave4. The Superpave5 concept is a modification to the conventional Superpave4 approach. Transportation Research Circular E-C300: Superpave5: How Increasing Air Voids Can Improve Asp... Transportation Research Circular E-C298 May 02, 2025 Simulation has become a crucial tool for evaluating the effectiveness of proposed capital investments aimed at improving transportation system performance. Factors such as persistent congestion, complex facility operations, and the rapid advancement of technologies and transportation systems management strategies have required agencies to invest in developing and utilizing simulation models. TR Ci... Transportation Research Circular E-C297 December 17, 2024 The most inherent advantage of a smooth pavement surface is its reduced noise levels compared to a pavement that is not smooth, but beyond the noise impacts there lies indirect and direct benefits that people gain from a	{ "page_id": null, "source": 7345, "title": "from dpo" }
smooth pavement. Transportation Research Circular E-C297: Concrete Pavement Smoothness: 2023 Workshop , from the Transportation Research Board, was developed from presentations ma... Transportation Research Circular E-C296 November 08, 2024 Federal laws and rules require performance standards to be implemented to enhance stewardship of the transportation infrastructure and foster greater innovation in delivering a resilient transportation system, including the life of pavement systems, that supports prosperity and opportunity. Transportation Research Circular E-C296: Foundation Design and Construction for 100-Year Pavement Systems do... Transportation Research Circular E-C295 August 15, 2024 Asphalt pavement stakeholders are working toward a common goal of net-zero emissions by 2050 and incorporating the use of technologies and tools to rationally quantify the environmental impacts of asphalt pavement materials and construction alternatives. Transportation Research Circular E-C295: Day-to-Day Practices to Reduce the Carbon Footprint of Asphalt , from the Transportation Research Board,... Transportation Research Circular E-C294 August 27, 2024 Asphalt mixture mechanical tests (such as Hamburg Wheel-Track, Asphalt Pavement Analyzer, Indirect Tensile Cracking) are growing in use by numerous state departments of transportation (DOTs) as part of their standard material specifications to complement volumetric properties and help ensure satisfactory asphalt mixture performance. Transportation Research Circular E-C294: Adjustment to Asphalt Mi... TR Circular E-C293 July 03, 2024 The design of asphalt mixtures for use in infrastructure applications has generated significant research and focus over recent years. Recent advancements in mechanical testing of asphalt mixtures, often referred to as "performance tests," brought to the asphalt community the concept of Balanced Mix Design (BMD) and the use of these tests to augment or go beyond volumetric design. TR Circular E-C29... Transportation Research Circular E-C292 June 12, 2024 Monitoring travel on the nation's roadways is crucial for understanding the dynamics of the U.S. transportation system. This involves both broad assessments, such as calculating annual average	{ "page_id": null, "source": 7345, "title": "from dpo" }
daily traffic to report on vehicle miles traveled, and detailed analyses, like examining freeway operations on a minute-by-minute basis. TR Circular E-C292: Advancing Highway Traffic Monitoring Through Strat... TR Circular E-C291 May 10, 2024 The increasing volume of plastic waste generated each year is a global problem—one that has been magnified following the 2017 passing of China’s Operation National Sword policy that ended the import of waste plastics into the country effective January 2018. Rightfully, this action has awakened a renewed effort to reduce and recycle plastic waste and asphalt pavements have been identified as a pote... TR Circular E-C290 May 22, 2024 Dielectric Profiling Systems and Paver Mounted Thermal Profiling can be used to advance pavement quality measurement of the entire mat from a limited number of random post-construction measurements to near-continuous measurements in real time during construction. TR Circular E-C290: Implementing Dielectric Profiling Systems for Real-Time Quality Control , from the Transportation Research Board, pr... Transportation Research Circular E-C289 April 24, 2024 The community of stakeholders in safe mobility for older adults use technical terms or expressions that can have very specific meanings across disciplines. The variety of different interpretations often leads to miscommunication. Moreover, the terminology continually changes to keep pace with advances in technology, measurement tools and methods, and transportation options. TRB's Transportation Re... Transportation Research Circular E-C288 February 16, 2024 The 4th Innovations in Freight Data Workshop was held September 19–21, 2023, at the Keck Center of the National Academies of Sciences, Engineering and Medicine in Washington, DC. TRB's Transportation Research Circular E-C288: Innovations in Freight Data: 2023 Workshop presents the discussions and presentations from the workshop. TR Circular E-C287 February 23, 2024 To encourage adoption of performance engineered mixtures (PEM) concepts, the U.S. Federal Highway Administration offered various levels of incentive funding to state	{ "page_id": null, "source": 7345, "title": "from dpo" }
agencies to help offset the costs of additional shadow testing, data collection, and reporting. TR Circular E-C287: Using Performance Engineered Mixtures to Improve Pavement Performance and Sustainability: State Experiences presents i... Transportation Research Circular E-C286 September 29, 2023 Traditionally, research and analysis of asphalt pavements have been siloed into pavement structural design, pavement material selection, and pavement service life. In order to achieve a truly perpetual pavement and potentially minimize life-cycle economic costs and environmental impacts, the pavement structural design and material design must also be integrated with pavement preservation and maint... TR Circular E-C285 September 15, 2023 The recent COVID-19 pandemic highlighted the significant consequences that can result from disruptions in supply chains. The massive disruptions that occurred because of the pandemic were the result of a “perfect storm” from several events. From panic buying to increases in demand for goods and e-commerce from home-bound consumers, to stalled port operations, and labor shortages, disruptions can c... TR Circular E-C284 May 24, 2023 The deployment of automated vehicles, shared mobility services, and other transformational transportation technologies has the potential to dramatically increase safety, reduce congestion, improve access, enhance sustainability, and spur economic development. However, success in meeting these goals is not assured and there are significant risks that these deployments could cause unintended consequ... TR Circular E-C283 July 24, 2023 TRB's International Conference on Low-Volume Roads provides a global forum to examine new technologies and new techniques in the planning, design, construction, operation, maintenance, and administration of low-volume roads. The Conference focuses on issues that impact all aspects of life throughout the world, including the first and last mile of the roads where trips by people, produce, and resou... Transportation Research Circular E-C282 December 23, 2022 Building information modeling (BIM) has been used in the vertical construction industry since the	{ "page_id": null, "source": 7345, "title": "from dpo" }
1970s. In the last decade, the worldwide transportation industry has been pushing for the implementation of BIM for bridges and infrastructures. This process revolutionizes the way projects are delivered and, to be successful, it requires the cooperation of all parties involved in the realization of t... Transportation Research Circular E-C281 October 26, 2022 One of several key outcomes of the 2021 Conference on Advancing Transportation Equity (CATE) was the determination that transportation equity can better be achieved by being intentional about facilitating context-specific, people-first practices, policies, and outcomes in the transportation industry. TRB's Transportation Research Circular E-C281: Advancing Transportation Equity: Conference Summary... Transportation Research Circular E-C280 October 28, 2022 The design of asphalt mixtures for use in infrastructure applications is a topic that has generated significant research and focus over recent years. TRB's Transportation Research Circular E-C280: Glossary of Terms for Balanced Design of Asphalt Mixtures provides a reference document for usage of Balanced Mix Design terminology by the asphalt mixtures community in the United States. Transportation Research Circular E-C279 September 02, 2022 The maritime industry at large has recognized the imperative to reduce localized and global emission impacts on our environment. There are numerous avenues to reducing vessel emissions, with one being the implementation of low- and zero-emission propulsion technology on vessels. TRB's Transportation Research Circular E-C279: Advancing Low- and Zero-Emission Marine Vessel Technology Options Worksho... Transportation Research Circular E-C278 April 07, 2022 The TRB Freight Data Technical Standing Committee initiated the third Innovations in Freight Data workshop to bring together freight data users and decision-makers to learn about and share the latest applications that leverage new and maturing data sources for improving decision-making. TRB's Transportation Research Circular E-C278: Innovations in Freight Data Workshop summarizes the September 202... Transportation Research Circular E-C277 February 18, 2022 During a time of	{ "page_id": null, "source": 7345, "title": "from dpo" }
ever-changing dynamics, there is a tremendous amount happening in the world of asset management. The 13th National Conference on Transportation Asset Management featured a variety of topics highlighting best practices in areas such as risk management, life cycle planning, and Transportation Asset Management Plan development. Emerging topics were also featured, addressing subjects ... Transportation Research Circular E-C276 January 12, 2022 Traffic speed deflection devices (TSDDs) are designed to measure pavement deflections or deflection velocities in response to loads applied by trucks moving at or near prevailing traffic speeds. TRB's Transportation Research Circular E-C276: State Departments of Transportation Experiences and Applications with Traffic Speed Deflection Devices details a 2019 workshop, Workshop on the Use of Traffic... Transportation Research Circular E-C275 December 17, 2021 When large-scale events disrupt freight systems, supply chains can fail, and populations are at risk of losing access to basic necessities and to critical goods flows needed to support infrastructure and economic recovery. TRB's Transportation Research Circular E-C275: Measuring and Managing Freight Resilience Workshop summarizes TRB's Measuring and Managing Freight System Resilience Workshop, whi... Transportation Research Circular E-C274 September 15, 2021 There has long been a focus on addressing the need for transportation agencies to incorporate more scientific approaches to developing construction and material specifications. TRB's Transportation Research Circular E-C274: Quality Assurance: Past, Present, and Future provides the synopsis of a workshop held during the TRB Annual Meeting in January 2020 that continued devloping this practice. Transportation Research Circular E-C273 July 09, 2021 There are hundreds if not thousands of variables to consider in foundation design, which require coordination between civil, structural, and geotechnical engineers as well as state departments of transportation (DOTs), environmental planners and other stakeholders, and require knowledge of the many design codes and constantly emerging research and design guidance. The TRB Technical Activity Divisi...	{ "page_id": null, "source": 7345, "title": "from dpo" }
Transportation Research Circular E-C272 May 28, 2021 Nearly all state departments of transportation (DOTs) have some level of oversight over local bridges, and different funding mechanisms and approaches are in use in the states. These are among the key takeaways from a best-practices panel sessions in conjunction with the 12th TRB International Conference on Low-Volume Roads. TRB's Transportation Research Circular E-C272: Technology Exchange on Loc... Transportation Research Circular E-C271 June 03, 2021 The aviation industry and federal government are investing significant resources to better understand and minimize the potential environmental impacts related to aviation. In some cases, environmental concerns have become a fundamental constraint to increases in aviation system capacity. Constrained capacity can further exacerbate environmental problems related to noise, local air quality, and oth... Transportation Research Circular E-C270 May 05, 2021 There is a widespread and heightened interest in both taking a hard look at where inequity exists and how to identify ways to address it with actionable solutions. The TRB National Cooperative Highway Research Program's Transportation Research Circular E-C270: Opportunities for Research on Transportation and Equity presents the outcomes of a TRB brainstorming session put forth as a challenge from ... Transportation Research Circular E-C269 February 03, 2021 The Commodity Flow Survey (CFS) provides key data for many state and federal freight planning activities. The CFS is a shipper survey used to gather freight flow information including commodity shipped, origin and destination, value and weight, and mode. TRB's Transportation Research Circular E-C269: 2020 Commodity Flow Survey Workshop summarizes a workshop that provided a platform for discussion ... Transportation Research Circular E-C268 January 11, 2021 In comparison to the levels of public interest and attention, there is little research to help understand the major obstacles and constraints encountered by women travelers and women working in transportation industries. TRB's Transportation	{ "page_id": null, "source": 7345, "title": "from dpo" }
Research Circular E-C268: Insights, Inclusion, and Impact: Framing the Future for Women in Transportation details the 2019 Women’s Issues in Transportation Co... Transportation Research Circular E-C267 November 05, 2020 Coronavirus (COVID-19) has proven a formidable adversary worldwide, with tremendous impact on the United States. The transportation system is an essential element of our response to this pandemic but has also been significantly impacted across all modes, both passenger and goods movement. This environment is where research is needed most. TRB's Transportation Research Circular E-C267: Summary of T... Transportation Research Circular E-C266 October 07, 2020 The COVID-19 pandemic has impacted transportation agencies across the U.S. in a variety of ways. On July 15, 2020, TRB's Transportation Asset Management Committee hosted a webinar that featured executives and CEOs from state, regional, and transit agencies. Transportation Research Circular E-C266: Transportation Asset Management in a COVID-19 World captures the details of the discussion on how the... Transportation Research Circular E-C265 September 29, 2020 TRB hosted the Transportation Resilience 2019: 2nd International Conference on Transportation Resilience to Natural Hazards and Extreme Weather Events (TR2019) at the National Academy of Sciences Building in Washington, D.C., November 13–15, 2019. The primary purpose of TR2019 program was to present advancements made in transportation systems resilience to natural hazards, climate change, and impa... Transportation Research Circular E-C264 July 31, 2020 The Conference on Health and Active Transportation brought together leaders from the transportation and health disciplines to chart a course for the future of active transportation. TRB's Transportation Research Circular E-C264: Conference on Health and Active Transportation compiles comments of the plenary sessions and individual breakout sessions. Transportation Research Circular E-C263 April 20, 2020 The use of performance measures and data is informing transportation decision making. Transportation Research Circular E-C263:Conference on Performance and Data in Transportation Decision Making summarizes	{ "page_id": null, "source": 7345, "title": "from dpo" }
many presentations from the conference, which attracted more than 350 professional transportation planners, consultants, industry experts, and academic researchers, from 42 stat... Transportation Research Circular E-C262 May 06, 2020 TRANSED is the International Conference on Mobility and Transport for Older Adults and People with Disabilities. Transportation Research Circular E-C262: TRANSED 2018 is a sample of current research and practice in the field of accessible transportation for older adults and people with disabilities. The research was presented at TRANSED on November 12-15, 2018, in Taipei, Taiwan. Transportation Research Circular E-C261 February 13, 2020 A clear funding and business case –neither of which have yet been clearly articulated – will be important for the success of AVs and shared mobility. Transportation Research Circular E-C261: TRB Forum on Preparing for Automated Vehicles and Shared Mobility: Mini-Workshop on the Economic Implications of Automated Vehicles and Shared Mobility details the roles of government and the public sector as ... Transportation Research Circular E-C260 February 12, 2020 Scaling loose rocks from slopes adjacent to highways is a simple and effective measure for temporarily reducing the risk of rockfall potential on naturally occurring bedrock outcrops and highway rock–soil cuts. However, the current practice in estimating scope of work and contracting rock scaling projects are inconsistent from agency to agency. Many owners and transportation agencies conduct scali... Transportation Research Circular E-C259 March 06, 2020 Transportation Research Circular E-C259: International Transportation and Economic Development Conference 2018 presents the proceedings from the ITED 2018. The report follows the general conference agenda, with presentations by speakers in the four plenary and 12 general sessions summarized. A list of the posters presented in one session is provided in Appendix A and the final program is provided ... Transportation Research Circular E-C258 December 11, 2019 The deployments of automated vehicles, shared mobility services,	{ "page_id": null, "source": 7345, "title": "from dpo" }
and other transformational transportation technologies have the potential to dramatically increase safety, reduce congestion, improve access, enhance sustainability, and spur economic development. However, success in meeting these goals is not assured, and there are significant risks that these deployments could cause unintended cons... TR Circular E-C257 November 08, 2019 Load testing of bridges to assess bridge performance has been in practice since at least 1891 in Switzerland. In times when engineering models were not as accurate and available as today, a critical step in the construction of a bridge was to load test prior to opening or during the opening ceremony of the bridge. Several bridges, including ones in Serbia, Switzerland, and France, collapsed during... Transportation Research Circular E-C256 December 06, 2019 Self-driving cars, rising temperatures and sea levels, increasingly strong weather events, changing citizen preferences, and innovations in technologies that are revolutionizing purchasing behavior, social interaction, financial transactions, communications, and travel—the transportation world is changing very rapidly. Transportation Research Circular E-C256: Managing Transportation Systems in a F... TR Circular E-C255 October 16, 2019 On April 9–10, 2019, 127 freight community members— including transportation professionals from transportation planning agencies, independent consultants, industry experts, and academic researchers from across North America—participated in the second Innovations in Freight Data Workshop in Irvine, California. Alison Conway from City College of New York chaired the planning committee for this works... Transportation Research E-Circular 253 October 25, 2019 Automated vehicles, shared mobility, and other transformational technologies in transportation provide a unique opportunity to make significant advances in meeting societal goals. TRB's Transportation Research E-Circular 253: Transformational Technologies in Transportation: Impacts on Traditional Research Processes and Programs explores whether and how, in an era of rapidly evolving transformation... TR Circular E-C254 October 02, 2019 Traditionally, pavement management decision-making has relied on surface cracking as an indicator	{ "page_id": null, "source": 7345, "title": "from dpo" }
of structural condition. However, with early-intervention preservation activities to extend the life of pavements, surface cracks no longer are a reliable indicator of structural condition. In the past 15 years, traffic speed deflection devices (TSDDs) have been developed to measure pavement structura... TR Circular E-C252 October 02, 2019 How do we bring governance into the era of digitization so it can manage demand and supply digitally? At the same time, it is necessary to correct for the existing inequities in our system, working closer with public- and private-sector partners and developing the infrastructure needed to ensure that the transition to shared and autonomous vehicles (SAVs) minimizes the potential challenges and tak... Transportation Research Circular E-C251 October 07, 2019 Information exchanged during the 97th Annual Meeting of the Transportation Research Board in a session titled "Relationship Between Laboratory Cracking Tests and Field Performance of Asphalt Mixtures" is captured in Transportation Research Circular E-C251: Relationship Between Laboratory Cracking Tests and Field Performance of Asphalt Mixtures . The document explores a significant amount of work t... September 16, 2019 The emergence of drug-impaired driving, notably marijuana-impaired driving, is a priority concern among road-safety stakeholders. In particular, the availability and potency of marijuana has increased, and the legalization of different forms of marijuana has occurred in many jurisdictions around the world. Of equal concern, in comparison to alcohol, much less is known about marijuana and driving i... September 06, 2019 TRB’s Technical Activities Division has released Transportation Research Circular E-C249: Key Elements of Construction Quality Assurance for Implementation, presenting a synopsis of " Quality Assurance: There’s Value in the Basics," held at the 2018 Annual Meeting of the Transportation Research Board. In this session, four speakers with a range of perspectives—the Federal Highway Administration (F... August 06, 2019 TRB’s Technical Activities Division has released	{ "page_id": null, "source": 7345, "title": "from dpo" }
Transportation Research Circular E-C248: 12th International Conference on Low-Volume Roads, highlighting topics including road surfaces, geotechnology, cold regions and climate change, pavement management, planning and economics, unpaved roads management, geosynthetics in low-volume roads, drainage and stream crossings, climate change resiliency, st... TR Circular E-C247 June 07, 2019 TRB’s Forum on Preparing for Automated Vehicles and Shared Mobility has released Transportation Research Circular E-C247: TRB Forum on Preparing for Automated Vehicles and Shared Mobility. The circular provides a summary of a February 2019 mini-workshop on the importance and role of connectivity within the automated vehicles and shared mobility environment. Key takeaways from the workshop su... June 06, 2019 TRB's Technical Activities Division has released Transportation Research Circular E-C246: Structural Monitoring as a primer to convey an understanding of how structural monitoring (SM) technology can be used most effectively. The circular is designed to help bridge owners understand the different purposes of structural health monitoring (SHM). Effective use of SHM can help determine the most cost-... June 19, 2019 TRB’s Technical Activities Division has released Transportation Research Circular E-C245: Transportation Oral History: State of the Practice and a Path Forward that highlights the availability of more than 1,000 transportation oral histories and includes a proposal for the creation of a guidebook that transportation organizations could use to create their own oral histories. The circular also expl... Transportation Research Circular E-C244 June 09, 2020 The current state of mobility on demand (MOD) is explored in Transportation Research Circular E-C244: Mobility on Demand: A Smart, Sustainable, and Equitable Future. The publication is the synopsis of a January 13, 2019, workshop that examined next steps for preparing for a transition to autonomy, and discussed ways to optimize sustainability and ensure equitability. The workshop emphasized the ro... April 19, 2019 TRB's Transportation Research Circular E-C243: SHRP	{ "page_id": null, "source": 7345, "title": "from dpo" }
2 Safety Data Student Paper Competition 2017-2019 contains student papers that were selected from a competition to promote use of the SHRP 2 Safety Data. A call for abstracts was issued in October 2017 to graduate students across the country, soliciting innovative ideas for using the data. The Review Panel for the SHRP 2 Safety Data Student ... January 09, 2019 TRB's Transportation Research Circular E-C242: A Literature Review of Rail Trespassing and Suicide Prevention Research reviews and summarizes available research reports and data sources related to the issues of railroad trespassing and suicide, focusing on research from 2013 onwards. This report explores incidences of rail-related trespassing and suicide based on several factors, including lethali... Transportation Research Circular E-C241 April 17, 2019 The notion of an aging and under-funded infrastructure in the United States is widely accepted. Current legislation calls for performance targets to be established to aid not only in the administering of funds, but also to assist states in identifying high-risk practices and roadways within their own networks. In addition to the performance targets, agency officials are looking to design and const... November 23, 2018 TRB's E-Circular 240: Workshop on Implementing a Freight Fluidity Performance Measurement System explored emerging tracking and measurement technologies, including blockchain, and examples of multisector data sharing to capture multimodal freight performance as discussed during a September 2018 conference. Performance of the freight transportation system is important to shippers and carriers, plan... December 26, 2018 TRB's E-Circular 239: Arterial Roadways Research Needs and Concerns: Informing the Planning, Design, and Operation of Arterial Roadways Considering Public Health explores the planning, design, and operation of arterials considering public health. This report presents a series of descriptive examples where arterials and health concerns appear in practice and identifies how and where health could be... December 20, 2018	{ "page_id": null, "source": 7345, "title": "from dpo" }
TRB's E-Circular 238: 2018 National Household Travel Survey Workshop explored users' experiences with the 2017 National Household Travel Survey (NHTS) dataset at an August 2018 workshop in Washington, D.C. Conducted by the Federal Highway Administration (FHWA), the NHTS is the authoritative source on the travel behavior of the American public. It is the only source of national data that allows one... November 13, 2018 Transportation Research E-Circular 237: Innovations in Asphalt Mixture Design Procedures explores the fundamentals of asphalt mix design for improved durability and performance. Based off of presentations made at TRB's 95th Annual Meeting, the document examines presentations that cover ways to incorporate more binder into the mix with trials that modify the air void and void in mineral aggregate (... October 05, 2018 TRB E-Circular 236: National Academies–TRB Forum on Preparing for Automated Vehicles and Shared Mobility summarizes the deliberations of a TRB forum launched in early 2018 to facilitate evidence-based research needed to deploy automated vehicle technologies in a manner and timeframe that informs policy to meet long-term goals. The deployments of automated vehicles, shared mobility services, and ot... TRB's E-Circular 235 September 09, 2018 TRB's E-Circular 235: Glossary of Transportation Construction Quality Assurance Terms: Seventh Edition contains common terms and accepted practice in transportation construction quality assurance terminology. Transportation construction quality assurance (QA), like many other specialized subject areas, has its own unique language containing numerous technical terms or expressions having very speci... TRB's E-Circular 234 September 07, 2018 TRB's E-Circular 234: Relationships of Laboratory Mixture Aging to Asphalt Mixture Performance summarizes the results from TRB Session 462: Relationship of Laboratory Mix Aging to Asphalt Mixture Performance, which was held during the 2016 TRB Annual Meeting. This circular includes four papers on addressing laboratory mix aging and explore handling asphalt mixtures at a production facility,	{ "page_id": null, "source": 7345, "title": "from dpo" }
varyin... Transportation Research Circular 233 June 05, 2018 TRB's E-Circular 233: Applying Census Data for Transportation explores a conference held on November 14-16, 2017, in Kansas City, Missouri that focused on the use of census data for transportation applications. The conference provided a forum for participants to share experiences with the use of Census data, including new techniques for integrating different data sets for use in transportation pla... April 13, 2018 TRB's E-Circular 232: Automated Vehicle Symposium 2017: Summary of a Symposium highlights the themes from an event that took place on July 11–13, 2017 in San Francisco, California. The event explored the development, testing, building, and deployment of autonomous vehicles (AVs). The 2017 AVS provided the opportunity for communication, collaboration, and information sharing on a wide range of topi... Transportation Research Circular E-C230 February 28, 2018 TRB's E-Circular 230:Culverts and Soil–Structure Interaction: Fifty Years of Change and a Twenty-Year Projection summarizes the presentations from the TRB 93rd Annual Meeting on January 14, 2014 in Washington, D.C. In the past 40 to 50 years have seen significant changes in the pipe industry in terms of materials used, structure sizes, shapes, and joint capabilities. Design methodologies hav... TR Circular E-C229 February 26, 2018 TRB's E-Circular 229: 10th SHRP 2 Safety Data Symposium: From Analysis to Results explores the October 6, 2017 symposium that served as a forum for the exchange of ideas about uses and methods for the SHRP 2 Safety Data Program and identified lessons learned from working with the data. This symposium focused on safety data analysis, results, and applications to help researchers and practitioners l... TR Circular E-C228 February 02, 2018 TRB's E-Circular 228: Rebuilding and Retrofitting the Transportation Infrastructure documents the presentations from a conference of the same name held in Washington, D.C., in September 2017. This	{ "page_id": null, "source": 7345, "title": "from dpo" }
meeting was the 11th in a series of Spotlight Conferences funded by the U.S. Department of Transportation’s (DOT) Office of the Assistant Secretary for Research and Technology, University Transportation ... TR Circular E-C227 December 21, 2017 TRB's E-Circular 227: Advancing Highway Traffic Monitoring Through Strategic Research explores the state of the practice and state of the art in highway traffic monitoring. It explores data acquisition, analysis and reporting tools, quality assurance and quality control techniques, and trends in emerging technologies. It explores how highway traffic data are acquired and used, and will provide the... November 20, 2017 TRB's E-Circular 226: Transportation System Resilience: Preparation, Recovery, and Adaptation explores research issues related to implementing transportation systems resilience, and explores themes of a whole system approach to resilience, weather and advances in forecasting, an integrated approach to cyber-physical security for transportation, a European perspective on research for resilient road... TRB's E-Circular 225 November 24, 2017 TRB's E-Circular 225: explores the presentations and discussions from a 2007 workshop that provided a forum for researchers, government officials, and private-sector representatives to exchange ideas on how the freight transportation system can be improved. Congestion in ports, on access roads to intermodal facilities, and on the rail system has significant impacts on the productivity and competit... TRB E-Circular 224 November 06, 2017 TRB's E-Circular 224: Eleventh International Bridge and Structures Management Conference summarizes a meeting held on April 26-27, 2017 in Mesa, Arizona that focused on the impacts of the new Federal Transportation Asset Management Rule and proposed federal performance measures. This report summarizes workshops that provided an overview of the federal rules; software implementation to help meet th... August 01, 2017 TRB's E-Circular 223: Innovations in Freight Data summarize the presentations and discussions that took place at the Innovations in Freight Data Summit on May	{ "page_id": null, "source": 7345, "title": "from dpo" }
17–18, 2017 in Irvine, California. The conference provided a forum to convene traditional freight-planning stakeholders with data and technology experts to discuss recent advances in the innovative application of these big and emerging data ... July 07, 2017 TRB's E-Circular 222: Automated Vehicles Symposium 2016 presents the proceedings from the Automated Vehicle Symposium (AVS) on July 19-21, 2016 in San Francisco, California. The 2016 AVS provided the opportunity for communication, collaboration, and information sharing on a wide range of topics, including potential public policy, safety and security, ethics, and equity concerns, as well as technol... TRB Transportation Research E-Circular 221 May 11, 2017 TRB's E-Circular 221: SHRP 2 Safety Data Student Paper Competition, 2015–2016 contains papers submitted to the first Student Paper Competition featuring applications of safety research from TRB's second Strategic Highway Research Program (SHRP 2). This competition features the use of the SHRP 2 Safety Data to extract new insights and applications of the data. Papers examine such topics as driver d... Transportation Research E-Circular 220 June 16, 2017 TRB's E-Circular 220: First International Roadside Safety Conference: Safer Roads, Saving Lives, Saving Money contains papers and abstracts presented at the TRB First International Roadside Safety Conference: Safer Roads, Saving Lives, Saving Money on June 12-15, 2017 in San Francisco, California. The conference supports and advances global efforts to reduce deaths and serious injuries associated ... Transportation Research E-Circular 219 March 15, 2017 TRB's E-Circular 219: The U.S. Department of Transportation’s Smart City Challenge and the Federal Transit Administration’s Mobility on Demand Sandbox: Advancing Multimodal Mobility and Best Practices Workshop features presentations and dialogue from a January 8, 2017 workshop at the TRB Annual Meeting. The workshop explored the role of public transit, shared mobility, and advanced technology (inc... TRB's E-Circular 218 January 02, 2017 TRB's E-Circular 218: Advancing	{ "page_id": null, "source": 7345, "title": "from dpo" }
Freeway Operations Through Strategic Research captures the state of affairs in freeway operations and reflects on the known universe of tools, techniques, and trends in emerging technologies in freeway management. From predictive software to electronic surveillance systems, operations have advanced rapidly in the past two decades. This publication will aid transport... E-Circular 217 December 20, 2016 TRB's E-Circular 217: Exploring New Directions for the National Household Travel Survey: Phase Two Report of Activities summarize the status, approach, and expected content of the new National Household Travel Survey data for the user community. The National Household Travel Survey (NHTS), administered by the Federal Highway Administration (FHWA), provided data on personal travel in the United Sta... E-Circular 216 December 05, 2016 TRB's E-Circular 216: International Experience and Perspective of Pavement Texture Measurements and Evaluation includes a synopsis of five presentations at the workshop “International Experience and Perspective of Pavement Texture Measurements and Evaluation” held at TRB's 94th Annual Meeting, January 11-15, 2015, in Washington, D.C. The presentations explore methods used in the United States, Uni... TRB E-Circular 215 November 28, 2016 TRB's E-Circular 215: Roadside Safety Design and Devices: International Workshop summarizes the presentations from a meeting hosted by the International Research Subcommittee of the TRB Roadside Safety Design Committee in Melbourne, Australia, on March 26, 2015. The publication explores assessment practices, work zone safety, safe systems and roadsides, hardware development and testing, and motorc... E-Circular 214 November 24, 2016 TRB E-Circular 214: International Practice in Highway Access Management: A Primer explores the international status of access management through the use of a survey of transportation researchers or professionals from eight countries to document their understanding of access management practices in their country.Authors of each country report were asked to focus on critical issues o... Transportation Research E-Circular November 22, 2016 TRB's	{ "page_id": null, "source": 7345, "title": "from dpo" }
E-Circular 213: 13th National Light Rail and Streetcar Conference: Transforming Urban Areas documents the papers and discussions from a conference that took place on November 15–17, 2015 in Minneapolis, Minnesota. The conference focused on how investments in light rail and streetcars may strengthen the entire transit network, contribute to regional mobility, and integrate successfully into t... Transportation Research E-Circular August 18, 2016 TRB E-Circular 212: The Future Locomotive: How to Manage What You Have Today With a View to the Future explores the presentations of a meeting held on July 30-31, 2013 in Omaha, Nebraska that examined locomotive cab design in terms of human machine interface theory and railroad applications. The meeting included perspectives from researchers, unions, locomotive engineers, engine manufacturers, and... TRB's Transportation Research E-Circular 211 July 15, 2016 TRB's E-Circular 211: Taxonomy and Terms for Stakeholders in Senior Mobility provides terminology that transportation professionals can use to communicate about senior mobility. The document will help those who encounter older adults with limited mobility, and will assist with communicating potential solutions to preserve and extend safe, independent transportation options for older persons. TRB E-Circular 210 July 07, 2016 TRB's E-Circular 210: Multimobility and Sharing Economy: Shaping the Future Market Through Policy and Research Multimodal explores the results of a workshop that focused on new developments in the shared-mobility sphere, the use of smartphones in pushing the goal of shared mobility forward, and on rural and suburban mobility problems. It also raised the issue of equity for paratransit options in r... TRB E-Circular 209 July 06, 2016 TRB's E-Circular 209: Integrating Asphalt Mixture Design, Structural Design, and Construction Quality Control provides an overview of some of the benefits and issues related to integrating asphalt mixture and structural design under the low-bid process in the United States. The e-circular is grouped	{ "page_id": null, "source": 7345, "title": "from dpo" }
into five areas: 1. An overview of the mechanistic–empirical (M-E) structural design process for bo... Transportation Research E-Circular 208 May 12, 2016 TRB's E-Circular 208: Transformational Technologies in Transportation: State of the Activities explores the status and applications of transportation goods, services, and systems that fall under the umbrella of transformational techology. Key transformational technologies include connected and automated vehicles, including shared use services; unmanned aerial systems (drones); Internet of Things (... E-Circular 207 May 10, 2016 TRB's E-Circular 207: Advancing Freight Fluidity Performance Measures: Summary of a Workshop details a December 9–10, 2015 workshop that examined the development and use of freight fluidity performance measures and related analysis techniques to improve the freight transportation system. Participants discussed the opportunities and challenges associated with expanding the use of freight fluidity p... TRB E-Circular 206 April 08, 2016 TRB E-Circular 206: Trends and Issues in Marine Transportation and the Environment explores urgent and far-reaching research topics pertinent to marine transportation and environmental issues. Subjects explored in this E-Circular include marine emissions and air quality impacts, including alternative fuels, human health impacts, improving marine vessel emission inventory methods, emission reductio... TRB E-Circular 205 March 11, 2016 TRB E-Circular 205: Commodity Flow Survey Workshop highlights an October 29, 2015 workshop that explored the Commodity Flow Survey (CFS), a data source for many freight planning activities. Workshop participants collaborated with the U.S Department of Transportation (DOT) Bureau of Transportation Statistics (BTS) to provide input to the next application of the survey. Input was provided to help in... E-Circular 204 March 03, 2016 TRB's E-Circular 204: Surface Transportation System Resilience to Climate Change and Extreme Weather Events highlights a September 16–18, 2015 conference and live webcast that convened more than 500 experts from across the world to explore state-of-the-art research and emerging practices and policies	{ "page_id": null, "source": 7345, "title": "from dpo" }
on adapting surface transportation networks to the potential impacts of climate change and extreme... Transportation Research Circular E-C203 February 15, 2016 TRB’s E-Circular 203: Transportation for Sustainability: An International Conference is the proceedings of a May 2015 conference held in Washington, D.C. that explored ways in which transportation systems can promote sustainability. TRB E-Circular 202 December 24, 2015 TRB E-Circular 202: Transportation Investment for Economic Development: Making the Case explores the presentations made at a peer exchange held August 17–18, 2015, in Detroit, Michigan. The meeting focused on collaboration between state departments of transportation (DOTs) and their state economic development counterparts. This exchange was designed to provide an opportunity for senior state DOT o... E-Circular 201 November 06, 2015 TRB E-Circular 201: Linking the Past to the Future: Lessons from History About Emerging Technology explores the presentations made at a one-day, invitational workshop that took place on June 13, 2014 and was hosted by the Intelligent Transportation Systems Joint Program Office (JPO) of the U.S. Department of Transportation and the History Committee of the Transportation Research Board. The worksho... TR Circular E-C200 August 14, 2015 TRB E-Circular 200: Transportation Asset Management from Plans to Practice: A Workshop for State Practitioners summarizes the presentations from a May 31, 2015 workshop held in conjunction with the 5th International Transportation Systems Performance Measurement and Data Conference, June 1–2, 2015, in Denver, Colorado. This circular summarizes ideas, experiences, and practices involving transporta... E-Circular 199 June 27, 2015 TRB E-Circular 199: Geotechnical Research Deployment explores how transportation organizations are implementing geotechnical research using new technologies, practices, and policies with the aim of developing and institutionalizing performance standards. The circular summarizes presentations from the 93rd Annual Meeting of the Transportation Research Board, which took place on January 14, 2014 in ... TRB E-Circular 198 June 15,	{ "page_id": null, "source": 7345, "title": "from dpo" }
2015 TRB E-Circular 198: Moisture Damage to Hot-Mix Asphalt Mixtures includes a synopsis of six presentations of the Moisture Damage to Hot-Mix Asphalt Mixtures Workshop conducted at the 91st Annual Meeting of the Transportation Research Board, January 22-26, 2012. TRB E-Circular 197 September 23, 2015 TRB E-Circular 197: Celebrating 50 Years of Traffic Flow Theory explores the presentations that took place at the Standing Committee on Traffic Flow Theory and Characteristics Summer Meeting, August 11–13, 2014 in Portland, Oregon. Presentations covered fundamental diagrams, traffic flow models, traffic control, freeway traffic analysis, calibration, empirical observations of traffic analysis, net... Transportation Research Circular E-C196 April 17, 2015 TRB’s E-Circular 196: Improving Safety Data Programs Through Data Governance and Data Business Planning summarizes the major themes of a peer exchange held on March 3-4, 2015, in Washington, D.C., which explored effective data governance and data business planning solutions for safety applications. Specifically, the conference focused on the business case for data governance, elements of data gove... Transportation Research Circular E-C 195 May 02, 2015 TRB’s E-Circular 195: Traffic and Transportation Simulation - Looking Back and Looking Ahead: Celebrating 50 Years of Traffic Flow Theory, a Workshop summarizes a workshop held January 12, 2014 at the TRB 93rd Annual Meeting that focused on traffic and transportation simulation. The workshop provided a means to explore the history, current status, and future of traffic simulation. TRB Electronic Circular E-C194 March 20, 2015 TRB E-Circular 194: Literature Searches and Literature Reviews for Transportation Research Projects addresses the necessary steps for producing a high-quality literature review for a transportation research project. The circular explores how to conduct literature searches; where to search for transportation information; how to put it all together as a quality literature review; and what the ... Transportation Research Circular E-C193 February 07, 2015 TRB’s	{ "page_id": null, "source": 7345, "title": "from dpo" }
E-Circular 193: Surface Transportation Financing: Innovation, Experimentation, and Exploration summarizes presentations made at the 5th International Conference on Surface Transportation Financing: Innovation, Experimentation, and Exploration on July 9-11, 2014, in Irvine, California. The conference focused on the latest research and practice in transportation finance, with an emphasis... Transportation Research Circular E-C192 February 04, 2015 TRB’s E-Circular 192: Data and Statistics for Valuing Transportation Infrastructure and Transportation's Contribution to the Economy summarizes presentations made at the Workshop on Data and Statistics for Valuing Transportation Infrastructure and Transportation’s Contribution to the Economy on July 23–24, 2014, in Washington, D.C. The workshop initiated a review of methods used to estimate ... Transportation Research Circular December 17, 2014 TRB’s E-Circular 191: Aligning Data Systems to Communicate with Decision Makers: A Peer Exchange summarizes a conference held in in Miami, Florida, on April 26–27, 2014, in conjunction with the 10th National Conference on Transportation Asset Management. The peer exchange, organized by TRB, focused on communicating with decision makers on transportation asset management, economic development... Transportation Research Circular E-C190 December 08, 2014 TRB’s E-Circular 190: Innovative Applications of the Highway Capacity Manual 2010 includes seven full technical papers and three extended abstracts focusing on applications of the Highway Capacity Manual 2010 (HCM 2010), as presented at the TRB 93rd Annual Meeting in January 2014. Transportation Research Circular E-C189 November 12, 2014 TRB’s E-Circular 189: Application of Asphalt Mix Performance-Based Specifications contains papers based on presentations made at TRB’s 93rd Annual Meeting in a session titled Application of Asphalt Mix Performance-Based Specifications. The session illustrated performance-based asphalt mix (PBAM) specifications that are being used by various agencies. It provided a review of the concepts behi... Transportation Research Circular E-C188 November 02, 2014 TRB’s E-Circular 188: Application of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Hot-Mix Asphalt:	{ "page_id": null, "source": 7345, "title": "from dpo" }
National and International Perspectives on Current Practice summarizes papers and presentations presented at a workshop that took place on January 12, 2014 at the TRB 93rd Annual Meeting. The workshop explored material characterization and field validation for short- and long-ter... Transportation Research E-Circular 187 October 27, 2014 TRB’s E-Circular 187: Developing Freight Fluidity Performance Measures summarizes presentations made at a workshop that examined freight fluidity as a measure of overall supply chain performance. The workshop also explored the use of freight fluidity performance measures in managing and improving the performance of the freight system. The Developing Freight Fluidity Performance Measures: Sup... September 30, 2014 TRB’s E-Circular 186 contains papers based on a workshop held at the 92nd Annual Meeting, which took place January 13-17, 2013 in Washington, D.C. The workshop focused on enhancing the durability of asphalt pavements, specifically on new design and construction approaches for extending pavement life while also improving their sustainability. The workshop also addressed the use of new materia... Transportation Research Circular E-C185 April 29, 2014 TRB’s E-Circular 185: The Future of TransXML: Workshop Summary is the proceedings of a December 2013 workshop that focused on potential future development and implementation of TransXML. Planning, designing, constructing, and operating transportation systems involve the exchange of large volumes of data. The lack of common data formats to facilitate the exchange of data across different busi... Transportation Research Circular E-C184 April 17, 2014 TRB E-Circular 184: Critical Issues in Aviation and the Environment 2014 explores issues that address the major environmental components affected by aviation activities, sustainable solutions that have evolved and continue to be developed to minimize aviation’s environmental impacts, and key processes that link aviation and the environment. The focus of the e-circular is on the state of scie... Transportation Research Circular E-C183 March 21, 2014 TRB’s	{ "page_id": null, "source": 7345, "title": "from dpo" }
E-Circular 183: Monitoring Bicyclist and Pedestrian Travel and Behavior is designed to chronicle the most recent advancements in techniques and technology of active transportation monitoring. The circular identifies a selection of recent advancements in bicycle and pedestrian data monitoring pertaining to both traffic volumes and behavioral data. The circular also introduces a selectio... January 09, 2014 TRB E-Circular 182: Progress Toward Performance-Graded Emulsified Asphalt Specifications addresses the current state of practice within the emulsified asphalt industry and examines new test methods that eventually could redefine how the industry determines specifications and performance of emulsified asphalts. This report builds on two e-circulars published in 2006 and 2007, E-C102 : Asphalt... Transportation Research Circular E-C181 December 12, 2013 TRB Transportation Research Circular E-C181: Risk-Based Adaptation Frameworks for Climate Change Planning in the Transportation Sector that explores leading climate change adaptation frameworks and examines the unique aspects of each framework’s development and approach. Recent studies of the climate change adaptation frameworks emerging from the transportation sector show a strong focus on risk. ... Transportation Research Circular E-C180 December 06, 2013 TRB’s Transportation Research Circular E-C180: Motor Vehicle Crashes and Injuries Involving Teenage Drivers summarizes participants' discussions on teenage driving that took place at a workshop in 2008. Transportation Research Circular E-C179 December 03, 2013 TRB’s Transportation Research Circular E-C179: Theory, Explanation, and Prediction in Road Safety summarizes the discussion and describes potential areas of advanced safety research identified by the participants at a November 2008 workshop. The objectives of the workshop were to explore promising future directions in highway crash data modeling and to identify potential areas for advanced researc... Transportation Research Circular E-C178 October 09, 2013 TRB’s Transportation Research Circular E-C178: Exploring New Directions for the National Household Travel Survey summarizes input on the design of the next National Household Travel Survey	{ "page_id": null, "source": 7345, "title": "from dpo" }
from the database’s user community. Transportation Research Circular E-C177 November 25, 2013 TRB’s Transportation Research Circular E-C177: Sustaining the Metropolis: Light Rail Transit and Streetcars for Super Cities summarizes the presentations made at a November 2012 conference that focused on introducing the concept of light rail transit (LRT) in North America. Transportation Research Circular E-C176 October 02, 2013 TRB Transportation Research Circular E-C176: Integrating Spatial and Business Data for Improved Decisions is the summary of peer exchange that took place in May 2013 in Boise, Idaho. Attendees at the exchange explore best practices for integrating spatial and business data, and discussed strategies to overcome barriers to implementing solutions. Participants explored both technical and organizatio... Transportation Research Circular E-C175 September 14, 2013 TRB’s Transportation Research Circular E-C175: Strategic Directions on Roadway Departure Crashes contains authored summaries of the presentations and breakout discussions from a August 2012 workshop that explored research needs regarding roadside departure crashes in support of the World Health Organization’s Decade of Action initiative. Transportation Research Circular E-C174 August 22, 2013 TRB’s Transportation Research Circular E-C174: Countermeasures to Address Impaired Driving Offenders provides an overview of the information presented and discussions held during an August 2011 symposium that explored the current state of knowledge about how best to deal with impaired driving offenders. Transportation Research Circular E-C173 June 12, 2013 TRB’s Transportation Research Circular E-C173: Glossary of Transportation Construction Quality Assurance Terms: Sixth Edition is a reference document for usage of transportation construction quality assurance (QA) terminology. The publication is designed to help foster improved communications among those who are involved in transportation construction QA. Transportation Research Circular E-C172 February 22, 2013 TRB Transportation Research Circular E-C172: Roadside Safety Design and Devices: International Workshop is a record of a meeting hosted by the International Research Subcommittee of the Roadside	{ "page_id": null, "source": 7345, "title": "from dpo" }
Safety Design Committee in Milan, Italy, on July 17, 2012. The focus of the meeting included assessment practices, safety systems, best practices, and other road safety products and issues. Transportation Research Circular E-C171 September 10, 2013 TRB Transportation Research Circular E-C171: Durability of Concrete: Second Edition provides information on producing durable concrete for transportation structures and pavements. The circular is an update to Transportation Research Circular 494: Durability of Concrete, published in 1999. Transportation Research Circular E-C170 December 20, 2012 TRB Transportation Research Circular E-C170: Nanotechnology in Concrete Materials: A Synopsis explores promising new research and innovations using nanotechnology that have the potential to result in improved mechanical properties, volume change properties, durability, and sustainability in concrete materials. Transportation Research Circular E-C169 October 18, 2012 TRB’s Transportation Research Circular E-C169: Measuring the Transportation System from a Supply Chain Perspective provides a synopsis of the information from a July 2012 workshop that was designed to help to advance the understanding of if and how public-sector decision making could be improved by having better supply chain information. The circular also summarizes initial themes that were identi... Transportation Research Circular E-C168 November 18, 2012 TRB Transportation Research Circular E-C168: Artificial Intelligence Applications to Critical Transportation Issues describes artificial intelligence (AI) applications in transportation and includes opinions on the future of AI by members of the committee that produced the report. The circular also contains 12 individually authored articles that describe five general AI areas: traffic operations, ... Transportation Research Circular E-C167 September 24, 2012 TRB’s Transportation Research Circular E-C167: The Promise of Rural Roads reviews the role of low-volume roads in rural connectivity, poverty reduction, crisis management, and livability. The circular is based on the keynote address at the TRB 10th International Conference on Low-Volume Roads held in 2011 in Florida. November 13,	{ "page_id": null, "source": 7345, "title": "from dpo" }
2012 TRB Transportation Research Circular E-C166: Glossary for Regional Transportation Systems Management and Operations Terms: Second Edition is to avoid the frequently occurring misconceptions that arise through the use of different terms for the same meaning. E-C166 is an update of a previous edition published in April 2009 as Transportation Research Circular E-C133: Glossary of Regional Transportat... Transportation Research Circular E-C165 August 29, 2012 TRB’s Transportation Research Circular E-C165: Alternative Binders for Sustainable Asphalt Pavement contains seven technical papers and summaries of presentations made at a January 22, 2012, workshop that explored material characterization and field validation for short- and long-term performance of various sustainable asphalt pavements. Electronic Circular E-C164 July 17, 2012 TRB's Transportation Research Circular E-C164: Climate Change and Transportation: Summary of Key Information highlights the key findings of a variety of studies on the subject of climate change and its ramifications for the transportation sector conducted by the National Research Council, the principal operating agency of the National Academy of Sciences and the National Academy of Engineerin... Transportation Research Circular E-C162 May 07, 2012 TRB’s Transportation Research Circular E-C162: Winter Maintenance and Surface Transportation Weather includes papers that were presented at the April 30-May 3, 2012, conference in Coralville, Iowa. Issues addressed by the papers include environmental stewardship and sustainability, road safety under winter conditions, decision support systems, winter surface friction, blowing and drifting snow, wi... January 15, 2012 TRB’s Transportation Research Circular E-C161: Applications of Advanced Models to Understand Behavior and Performance of Asphalt Mixtures is a synopsis of information on the applications of advanced models to understand behavior and performance of asphalt mixtures. January 15, 2012 TRB’s Transportation Research Circular E-C160: Polyphosphoric Acid Modification of Asphalt Binders: A Workshop documents the research discussed and presentations made at a April 2009 workshop that explored polyphosphoric acid-modified	{ "page_id": null, "source": 7345, "title": "from dpo" }
asphalt and its performance. The circular includes presentations made on a survey on polyphosphoric acid use and issues; the why and how of polyphosphoric acid modif... December 07, 2011 TRB’s Transportation Research E-Circular E-C159: Teamwork in U.S. Railroad Operations: A Conference is a summary of the proceedings from an April 2009 conference that explored how modern teaming strategies might assist in improving the safety of railroad operations in the United States. The circular includes background papers, presentations, and summaries of breakout sessions held during the confe... September 23, 2011 TRB's Transportation Research E-Circular E-C158: Commodity Flow Survey Workshop is the proceedings of a November 2010 workshop that explored the next application of the Commodity Flow Survey (CFS). The CFS is a key data source for a myriad of freight planning activities. October 10, 2011 TRB’s Transportation Research Circular E-C157: TRIS Turns 40: Results of a 2007 User Satisfaction Survey on the Transportation Research Information Service (TRIS) documents the results of an online survey of users of the TRIS database. The circular also includes background and information on the history and evolution of TRIS, information on several different versions of TRIS, and a discussion of T... July 18, 2011 TRB’s Transportation Research E-Circular E-C156: Automated Imaging Technologies for Pavement Distress Surveys documents state-of-the-art techniques and technologies in the acquisition of pavement surface images, and basic requirements needed to automatically identify and classify pavement surface distresses. The basics of film or magnetic tape–based image acquisition are presented in the circular.... July 13, 2011 TRB’s Transportation Research E-Circular E-C155: Sensitivity Analyses for Flexible Pavement Design with the Mechanistic–Empirical Pavement Design Guide contains the proceedings of a workshop that was held in conjunctions with the 2010 TRB 89th Annual Meeting. The workshop was developed to provide information for transportation agencies in the process of,	{ "page_id": null, "source": 7345, "title": "from dpo" }

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