Timeout Period Research Articles

The focus on life-prolonging anticancer treatment hampers shared decision-making in people with advanced cancer: A qualitative embedded multiple-case study.

Implementing shared decision-making in oncology practice is often limited, particularly integrating the patient's context into decision-making. To improve this, we conducted a quality improvement project, CONtext. CONtext attempts to accomplish this by: (1) Integrating the patient's context into shared decision-making during consultation with the medical oncologist; (2) Actively involving the GP and case manager (a specialized oncology nurse), who often have knowledge about the patient's context, and; (3) Giving the person with advanced cancer a time-out period of up to 2 weeks to consider and discuss treatment options with others, including close family and friends. To explore how persons with advanced cancer and their involved professionals experienced shared decision-making after the introduction of CONtext. A qualitative embedded multiple-case study using in-depth interviews analysed with inductive content analysis. A purposive sample of 14 cases, each case consisting of a patient with advanced cancer and ideally their medical oncologist, case manager, and GP. Four themes were identified: shared decision-making is a dynamic and continuous process (1), in which the medical oncologist's treatment recommendation is central (2), fuelled by the patients' experience of not having a choice (3), and integrating the patient's context into shared decision-making was considered important but hampered (4), for example, by the association with the terminal phase. The prevailing tendency among medical oncologists and persons with advanced cancer to prioritize life-prolonging anticancer treatments restricts the potential for shared decision-making. This undermines integrating individual context into decision-making, a critical aspect of the palliative care continuum.

Automatically adapting system pace towards user pace — Empirical studies

An interactive application’s overall pace of interaction is a combination of the user’s pace and the system’s pace, and if the system’s pace is mismatched to the user’s pace (e.g., timeouts or animations are too fast or slow for the user), usability and user experience can be impaired. Through a series of four studies, we investigated whether users prefer systems where the system’s pace better matches their own pace. All of the studies used common drag-and-drop interactions with hierarchical folder widgets, in which a folder would expand when the cursor hovered over it for a timeout period. If the system pace in these interactions is too fast (i.e., the timeout is too short), then the user’s performance and subjective experience is likely to be impaired because of unintended expansions; and if the system pace is too slow (i.e., the timeout is too long), then performance and experience could be impaired by unnecessary delay before folders expand. The first experiment was designed to validate the premise that fast-paced users prefer a fast system pace to a slow one (and the inverse for slow-paced users), and results confirmed this premise. The second study used the first experiment’s data to look for measures of user pace that could enable automatic adaptation of system pace, and also examined whether participants adjusted their pace towards that of the system. The study found reliable measures of user pace and showed that participants do entrain to the system’s pace. The third and fourth studies examined whether users would prefer a system that adapted its pace to the user over a system that used a static baseline pace. Results indicated that a majority of fast-paced users preferred the adaptive interface, but that slow-paced users generally preferred the static baseline interface. We discuss several design implications, including opportunities for systems to improve user experience for fast users by automatically adapting system pace to user pace.

The Effects of Export Market Re-Entry and Time-Out Period on Innovation

The Effects of Export Market Re-Entry and Time-Out Period on Innovation

Re-internationalization and Firm’s Post-re-entry Performance: The Role of International Heritage

This paper studies the drivers of re-internationalization to export market and post-re-entry performance from the perspective of international heritage. We develop a conceptual framework to explain how three key aspects of international heritage (firm specific competitive advantage, market and product diversification strategies, and overall exporting experience) as well as firm’s time-out period drive re-internationalisation. Using granular trade transaction-level firm exports data from UK HM Revenue & Customs linked with profit records for 2002-2013, we found that, despite their inter-relationships, re-entry and post-re-entry performance are driven by different mechanisms, and therefore, the same factor may influence them differently or even in an opposite direction. In other words, what increases the chances of firm’s re-entry, may prove to be detrimental for their performance and vice versa.

Taking a time-out from exporting: Implications for the likelihood of export re-entry and re-entry export performance

Drawing from Organizational Learning Theory, we explain how the “time-out period” from exporting affects a) the likelihood of re-starting exporting and b) re-entry export performance. We also explain how foreign collaboration influences these two relationships. We show that the time-out period has an inverted U-shaped relationship with the likelihood of re-starting exporting, and a U-shaped relationship with re-entry export performance. Foreign collaboration enhances managerial confidence and thereby increases the likelihood of re-starting exporting during the earlier phases of the time-out period. It also enhances re-entry export performance by accelerating new knowledge accumulation in the later phases of the time-out period.

The Role of Astroglial xCT in Mitigating Cue‐Induced Amphetamine‐Seeking

Relapse poses a significant barrier to the development of effective treatments for substance use disorder (SUD). Cue‐induced drug craving increases during drug abstinence, potentially affecting the efficacy of treatments for SUD. Disruptions in glutamatergic signaling are characteristic of SUDs. Glutamate is maintained by a combination of astrocytic and neuronal transporters within the nucleus accumbens (ACb) and disruptions in this homeostasis engender SUD. One transporter, the cysteine‐glutamate transporter (xCT), is primarily localized on astrocytes and helps maintain glutamate concentrations. This process is disrupted by cocaine use, leading to increased cue‐induced craving. The therapeutic N‐acetylcysteine (NAC) lowers cue‐induced relapse to cocaine. However, little research has shown how these effects extend to other psychostimulants, such as amphetamine (AMP). Though both are psychostimulants, AMP and cocaine have distinct mechanisms of action in the brain, particularly with regards to dopamine neurotransmission. In the present study, we assessed disruption of astrocytes and xCT expression following AMP self‐administration (SA). We also assessed the degree to which disruptions in astrocyte or xCT expression might explain an increased propensity for relapse when presented with drug cues and the degree to which NAC can attenuate relapse.78 male Sprague‐Dawley rats were surgically implanted with jugular catheter to allow for intravenous SA of AMP. Upon recovery, all rats underwent 14, 2‐hr fixed‐ratio‐1 SA sessions for AMP or the saline (SAL) control. Active lever presses resulted in an infusion of amphetamine (0.1 mg/kg/infusion) which was followed by a 20 s time‐out period signaled by the illumination of both cue lights. After 14 SA sessions, all rats entered a forced abstinence period where they were not exposed to the drug or drug‐related cues. During abstinence, all rats were given daily injections of NAC (100 mg/mL/ip) or the saline vehicle. Cue‐induced relapse tests were conducted at the cessation of the abstinence period. During the relapse test, active lever presses resulted in the illumination of the cue lights present during SA testing, but no delivery of the drug itself. One subset of rats underwent relapse testing after one withdrawal day (WD) 1 and one subset underwent testing on WD 14 to examine any increases in relapse. Following testing, all rats were perfused and brains were extracted for immunofluorescence (IF) analysis of astrocyte and xCT transporter expression within the ACb and medial prefrontal cortex using a simultaneous immunofluorescence (IF) method.During the cue‐induced relapse test, cue‐induced responding was significantly higher in AMP‐treated rats compared to SAL‐treated rats. Importantly, NAC failed to attenuate relapse at either WD 1 or WD 14. We hypothesized that xCT expression would remain unaltered between WD 1 and WD 14 for rats treated with NAC. However, given that NAC failed to lower relapse at either time point, IF results will help determine inform the inefficacy of NAC. For instance, should xCT expression remain unaltered between AMP and SAL‐exposed rats, then it would make sense that NAC would likely have little success in lowering relapse. Such a finding would suggest that AMP disrupts glutamate via a different mechanism than cocaine. Thus, results may indicate that the therapeutic efficacy of NAC varies across psychostimulants.

A Study on IFM/IFG/1 Vacation Queueing System with Breakdown, Repair and Server Timeout in (Triangular, Trapezoidal & Pentagon) Intuitionistic Fuzzy Set using α-Cuts

In this, we studied and investigated IFM/IFG/1 vacation queueing system/waiting line with server breakdowns, repair and server timeout, “by using (Triangular Trapezoidal and Pentagonal) IF (Intuitionistic Fuzzy) numbers with the application of IFS (Intuitionistic fuzzy set). Here we operate single server vacation queueing system in the following manner; when the system finds empty, the server waits for fixed time ’c’ known as server timeout. At the expiration of this time, if no one arrives into the system, then server takes the vacation. If anyone arrived in the system during the timeout period as well as in vacation the server commences the service otherwise, he will go for another vacation. If the system had occurred with a breakdown, just after a break down the server undergoes for repair. After the repaired process is completed the server restarts the service to the arrived customer. By the approach of IFS properties, we develop the membership function of the system performance are of fuzzy nature. Based on IFS α-cut approach the Intuitionistic fuzzy queues are reduced to a family of ICS (Intuitionistic Crisp Set). The numerical results are illustrated to the model.

Fewer Wrong-Site Peripheral Nerve Blocks Following Updates to Anesthesia Time-Out Policy.

Background: Peripheral nerve block (PNB) has been shown to be safe and effective, and its use has continued to increase, but it is not without risks. One potentially preventable risk is wrong-site blocks (WSBs). Our institution mandated a time-out process before PNB in 2003, and then in 2007 made two more changes to our policy to mitigate risk: (1) the circulating/block nurse was the only person permitted to access the block needles; after a time-out period was complete, the nurse gave the needles to the anesthesiologist; and (2) the nurse remained at the patient's bedside until the PNB was initiated. Purpose: We sought to compare the incidence of WSBs before and after this time-out process was implemented in 2003 and the enhanced form of it was implemented in 2007. We hypothesized that the enhanced process would decrease the incidence of WSBs. Methods: We retrospectively analyzed data, from January 2003 to December 2016, taken from the quality assurance and performance improvement (QA/PI) division of the anesthesiology department at our institution, which maintained daily statistics on anesthetic types using quality audits from paper or electronic anesthesia records. All WSBs from this period were reported to the QA/PI division and root cause analyses performed. The incidence of WSB was compared pre- and post-implementation of the enhanced time-out policy for upper extremity, lower extremity, and all blocks by calculating relative risks with 95% score confidence intervals and performing Fisher's exact tests. Results: The incidence of WSBs decreased from 1.10/10,000 before changes to the policy were initiated to 0.24/10,000 afterward. Conclusion: We observed an association between the implementation of a dynamic, team-focused time-out process and a reduction in the incidence of WSBs at our institution. A causal effect of the enhanced time-out cannot be determined given the risk of bias associated with before-after study designs and our lack of adjustment for potential confounders. Further research is therefore warranted.

Receptor Mechanisms in Nicotinic Enhancement of Opioid Antinociception

The use of prescription opioids for pain management can be limited by their adverse behavioral effects, which usually are not measured in the initial preclinical assessment of established or novel candidate analgesics. Recently, we have developed a protocol for concurrently assessing the antinociceptive effects of drugs (an indicator of analgesic promise) and their ability to decrease rates of operant behavior (an indicator of unwanted behavioral effects). Under these procedures, nicotine has been shown to augment the antinociceptive, but not the rate‐decreasing, effects of opioid analgesics with an inverse relationship to efficacy at the m‐opioid receptor‐ e.g., nicotine‐induced enhancement of nalbuphine>oxycodone>fentanyl. The present study was designed to further elucidate nicotinic‐opioid interactions by exploring the role of nicotinic receptor efficacy in the nicotinic augmentation of opioid antinociception. Male squirrel monkeys (n=4) lever‐pressed under a fixed ratio (FR) 10 schedule of 20% (v/v) condensed milk reinforcement. A 30‐s timeout (TO) period followed either the completion of the FR 10 or the elapse of 20‐s (limited hold (LH) 20). During the 30‐s TO, the distal portion of the monkey’s tail was immersed in 35, 50, 52, or 55°C water, and the latency to remove the tail was recorded. Dose response functions for tail‐withdrawal latency and decreases in response rate were generated for the high efficacy m‐opioid agonist fentanyl and the low efficacy m‐agonist nalbuphine alone and in the presence of nicotinic agonists reported to have high or intermediate efficacy‐‐epibatidine (0.00056 mg/kg) or varenicline (0.032 mg/kg), respectively. Fentanyl dose‐dependently increased tail‐withdrawal latencies at all water temperatures and, concomitantly, decreased rates of responding. Nalbuphine did not significantly decrease response rate, and increased tail‐withdrawal latencies at 50 and 52°C, but not at 55°C. Neither epibatidine nor varenicline significantly modified the rate decreasing effects of any of the opioids or the antinociceptive effects of fentanyl. However, the antinociceptive potency of nalbuphine was markedly enhanced by epibatidine (up to ~70‐fold) and only slightly increased by varenicline. The present results add to previous findings with nicotine, showing that nicotinic enhancement of opioid antinociception is inversely related to m‐opioid efficacy. They also extend those findings to suggest that such adjuvant effects are more robustly produced by nicotinic full agonists (nicotine, epibatidine) than a partial agonist (varenicline). In conjunction with previous reports, these findings support the idea that nicotinic agonists may be clinically useful as adjuvants for opioid analgesia.Support or Funding InformationDA035857 and Harvard Medical School Livingston Fellowship

Performance Analysis of the Raft Consensus Algorithm for Private Blockchains

Consensus is one of the key problems in blockchains. There are many articles analyzing the performance of threat models for blockchains. But the network stability seems lack of attention, which in fact affects the blockchain performance. This paper studies the performance of a well adopted consensus algorithm, Raft, in networks with non-negligible packet loss rate. In particular, we propose a simple but accurate analytical model to analyze the distributed network split probability. At a given time, we explicitly present the network split probability as a function of the network size, the packet loss rate, and the election timeout period. To validate our analysis, we implement a Raft simulator and the simulation results coincide with the analytical results. With the proposed model, one can predict the network split time and probability in theory and optimize the parameters in Raft consensus algorithm.

Underlying and Persistence Fault Diagnosis in Wireless Sensor Networks Using Majority Neighbors Co-ordination Approach

The faults in wireless sensor network are classified according to the underlying causes, behavior, and persistence with respect to the observation time. Due to underlying causes, faults are classified as fail and stop, crash, omission, timing, and incorrect computation fault. Due to behavior, faults are classified as hard and soft fault. Due to persistence, faults are classified as permanent, intermittent, and transient fault. As the recent state-of-art fault diagnosis is a significant requirement for each application of wireless sensor network. In this research paper, we have proposed a fault diagnosis protocol using majority neighbors coordination based approach for wireless sensor network. Precisely, a multiple-hop data received technique, timeout period mechanism, timeout request and response message exchange, timeout early and delay message exchange, and degree of belongingness using Gaussian function mechanism are used for the detection of faults such as fail and stop, crash, omission, timing, and incorrect computation. The mean difference and standard error comparison with different threshold condition are used for soft (permanent, intermittent, and transient) fault detection, and timeout response mechanism with different threshold condition is used for hard (permanent, intermittent, and transient) fault detection. After fault detection, the actual fault status of the sensor node is confirmed by the one-hop majority neighbor sensor nodes. For validation of the proposed fault detection algorithms, simulation experiments are conducted by the network simulator NS-2.35. The experimental results show the substantially parameters performance such as fault detection accuracy, false alarm rate, false positive rate, and false classification rate with increasing the fault probability for different average degree of the sensor nodes in the network.

Enhancement of Opioid Antinociception by Nicotine.

Nicotine can produce antinociception in preclinical pain models; however, the ability of nicotine to augment the antinociceptive effects of opioid agonists has not been investigated. The present experiments were conducted to determine how nicotine modifies the effects of opioid agonists differing in efficacy. Male squirrel monkeys responded for the delivery of milk under a fixed ratio 10 schedule of reinforcement. During the 30-second timeout period following each milk delivery, the subject's tail was immersed in 35, 50, 52, or 55°C water, and the latency to remove the tail was recorded. Dose-response functions for tail-withdrawal latency and operant performance were determined for fentanyl, oxycodone, buprenorphine, and nalbuphine alone and after treatment with nicotine. Excepting nalbuphine, all opioids produced dose-related disruptions in food-maintained responding and increases in tail-withdrawal latency at each water temperature. Nicotine did not exacerbate the behaviorally disruptive effects of the μ-opioids on operant performance but produced a significant mecamylamine-sensitive enhancement of the antinociceptive potency of each opioid. Failure of arecoline to augment the antinociceptive effects of oxycodone and antagonism by mecamylamine suggests this nicotine-induced augmentation of prescription opioid antinociception was nicotinic acetylcholine receptor (nAChR) mediated. This was reflected in leftward shifts in the antinociceptive dose-response curve of each opioid, ranging from 2- to 7-fold increases in the potency of oxycodone across all water temperatures to an approximately 70-fold leftward shift in the antinociceptive dose-response curve of nalbuphine at the lower and intermediate water temperatures. These results suggest that nicotine may enhance μ-opioid antinociceptive effects without concomitantly exacerbating their behaviorally disruptive effects. SIGNIFICANCE STATEMENT: Prescription opioids remain the most effective pain-management pharmacotherapeutics but are limited by their adverse effects. The present results indicate that nicotine enhances antinociceptive effects of various opioid agonists in nonhuman primates without increasing their disruptive effects on operant performance. These results suggest that nicotine might function as an opioid adjuvant for pain management by enabling decreased clinically effective analgesic doses of prescription opioids without exacerbating their adverse behavioral effects.

Delay-sensitive Task Scheduling with Deep Reinforcement Learning in Mobile-edge Computing Systems

Mobile-edge computing(MEC) is considered to be a new network architecture concept that provides cloud-computing capabilities and IT service environment for applications and services at the edge of the network, and it has the characteristics of low latency, high bandwidth and real-time access to wireless network information. In this paper, we mainly consider task scheduling and offloading problem in mobile devices, in which the computation data of tasks that are offloaded to MEC server have been determined. In order to minimize the average slowdown and average timeout period of tasks in buffer queue, we propose a deep reinforcement learning (DRL) based algorithm, which transform the optimization problem into a learning problem. We also design a new reward function to guide the algorithm to learn the offloading policy directly from the environment. Simulation results show that the proposed algorithm outperforms traditional heuristic algorithms after a period of training.

Export market re-entry: Time-out period and price/quality dynamisms

The relevance of nonlinear internationalisation regarding exporting activities and the performance post re-entry remains little understood. This study develops a two-stage model to explain the process of exporting firms’ exit and re-entry decisions regarding individual export markets. Specifically, it investigates the dynamic relationships between exit and re-entry stages by focusing on the time-out period. This study empirically tests the decision model by employing export data from the Chinese Customs for the period 2000-2009. The results indicate the importance of the exit stage in shaping re-entry decisions, price/quality ratio and export performance, where time-out period plays a significant role in varying these effects.

Broadcast Based Code Dissemination Scheme for Duty Cycle Based Wireless Sensor Networks

The technology of software-defined devices has great prospect in updating the programs of the sensing devices to enable the devices to adapt to the new environments and applications. However, to effectively spread the code to each node in the software-defined-based wireless sensor networks (WSNs) is still a challenging task. In this paper, a proportion to duty cycle length-based broadcast (PDLB) scheme is proposed to disseminate code in duty cycle-based WSNs in a fast and energy-efficient style. In PDLB scheme, the sink first initiates a code broadcast. Then, the nodes that have received code start counting and calculate the priority of broadcasting based on an improved counter-based priority broadcasting approach proposed in this paper. Next, the nodes with the highest priority select k slots to broadcast according to the length of duty cycle so that the code can be spread from the sink to the network periphery. Finally, the nodes that have not obtained the code wait for a period of timeout to broadcast to actively send code request; after receiving code request, the node that obtained the code initiates a code broadcast to cause the code requester to obtain the code. The PDLB scheme has been validated by comprehensive experiments that show the following regularities. The smaller the count threshold value C h , the larger the number of slots selected for broadcasting that can guarantee a certain coverage ratio, while the code dissemination speed slows down at the same time. The longer the duty cycle is, the more the broadcast time is required, and the larger the transmission delay is. For each slot added in a working cycle, the number of broadcasts is increased by 1.54%-33.33% and the transmission delay is augmented by 2.27%-70.04%. The higher the node density is, the shorter the code spread speed is. As the network density increases, the transmission delay is reduced by 0.83%-65.87%. When the number of broadcasting slots is half of the total number of slots in a work cycle, the energy consumption reaches the lowest value.

Once bitten, not necessarily shy? Determinants of foreign market re-entry commitment strategies

We investigate foreign market re-entry commitment strategies, namely the changes in the modes of operation (commitment) undertaken by multinational enterprises (MNEs) as they return to foreign markets from which they had previously exited. We combine organisational learning theory with the institutional change literature to examine the antecedents of re-entry commitment strategies. From an analysis of 1020 re-entry events between 1980 and 2016, we find that operation mode prior to exit is a strong predictor of subsequent re-entry mode. Contrary to the predictions of learning theory, we did not find support for the effect of experience accumulated during the initial market endeavour on the re-entry commitment strategies of MNEs. In turn, exit motives significantly impact on the re-entrants’ decision to re-enter via a different mode of operation, by either increasing or decreasing their commitment to the market. We show that re-entrants do not replicate unsuccessful operation mode strategies if they had previously underperformed in the market. When favourable host institutional changes occur during the time-out period, re-entrants tend to increase commitment in the host market irrespective of the degree of prior experience accumulated in the market.

Abuse‐Related Discriminative Stimulus Effects of Synthetic Cathinones

The use of synthetic cathinones, or “bath salts,” has become more widespread in recent years. “Bath salts” share many chemical properties with psychostimulants like methamphetamine or with entactogens like 3,4‐methylenedioxymethamphetamine (MDMA or “Ecstasy”), presumably reflecting structural differences that lead to differing neurochemical actions. Yet, currently available synthetic cathinones have not been well‐characterized in primate species, and it is unclear which pharmacological activity mediates their abuse‐related behavioral effects. The present study was initiated to address this question, using drug discrimination procedures to evaluate several synthetic cathinones in two groups of squirrel monkeys. Each subject was trained to respond on either of two levers under a FR10 schedule of reinforcement and, during training sessions, responding on one lever was reinforced after pretreatment with vehicle whereas responding on the second lever was reinforced after pretreatment with the training drug. Under terminal conditions, one group of monkeys discriminated 0.1 mg/kg methamphetamine from saline; the other group discriminated 0.6 mg/kg MDMA from saline. Drug or saline lever assignments were counter balanced across the left and right levers within each group. Training sessions comprised multiple components, and a component consisted of a ten‐minute timeout period followed by ten presentations of the FR10 schedule, each followed by a brief 50‐second timeout. After criterion performance was met (≥ 90% correct), test days interspersed training days, with at least two training days between each test day. The effects of five different synthetic cathinones ‐ α‐pyrrolidinovalerophenone (α‐PVP), methylenedioxypyrovalerone (MDPV), mephedrone, methylone, and methcathinone) were tested in both groups. A full range of doses of each drug was administered using cumulative dosing procedures. Results show that doses of 0.1 mg/kg – 0.32 mg/kg of MDPV, α‐PVP, and methcathinone were identified as methamphetamine in subjects trained to discriminate 0.1 mg/kg methamphetamine from vehicle, whereas doses mephedrone and methylone up to those that decreased overall response rates did not generalize to MA. Preliminary results suggest an opposite profile of substitution in MDMA‐trained animals. Thus, mephedrone and methylone, but not MDPV, α‐PVP, and methcathinone did appear to generalize to MDMA. These results demonstrate that synthetic cathinones have differing substitution profiles in animals trained to discriminate methamphetamine or MDMA, which may reflect differing subjective effects and, perhaps, differing abuse liability in man.Support or Funding InformationSupported by NIH Grants: DA002519. GM113117, DA039306, GM111385This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Superiority of Buprenorphine over Suboxone in Preventing Addiction Relapse in Opioid Addicts under Maintenance Therapy: A Double-Blind Clinical Trial

Background: In maintenance therapy for opioid addiction, to reduce the risk of buprenorphine (BUP) abuse, the combination of BUP and naloxone (NX) has been developed and is commercially available as suboxone (BUP/NX). This study was designed to compare addiction relapse frequency in patients receiving BUP and BUP/NX as maintenance therapy. Methods: In this double-blind clinical trial with cross over design, 100 opioid abusers were randomly assigned to two treatment groups to receive either BUP or BUP/NX. After three months, without a time-out period, subjects undertook treatment with the other drug. The subjects were screened weekly for urinary morphine. Results: In each of the study arms, when the patients were given BUP/NX, the number of relapses was significantly higher compared to when they received BUP (0.13±0.24 vs. 0.04±0.09, P = 0.001). If participants� age was taken into account, the number of relapses was significantly higher when BUP/NX was given in age groups of 31 to 40 years and over 50 years (P < 0.05). The length of addiction had also a significant impact on the number of relapses, i.e., patients with over 10-year history of addiction had higher number of relapses if they were given BUP/NX compared with BUP (P < 0.05). Conclusion:BUP seems to be more effective than BUP/NX in preventing addiction relapse in opioid abusers under maintenance treatment.

Potential energy savings from high-resolution sensor controls for LED lighting

LED lighting systems paired with high-resolution sensor systems offer great potential for substantial energy savings via enhanced control options, and have other value-added features. We used modelling and demonstrations in a full-scale office test bed to illustrate this potential. First, we propose that such a system enables much shorter timeout periods for occupancy sensing: the higher density of sensors provides more reliable occupancy detection and LEDs are impervious to lifetime degradation from the consequent increased switching frequency. We used occupancy data measured in real office environments to estimate that a reduction in timeout period from the current code maximum of 20min to 1min would yield 26% additional energy savings. Further, we installed 72 LED luminaires in an office test bed with windows; each luminaire featured a co-located motion sensor and light sensor. The localized light sensor enabled daylight harvesting at each fixture to be optimized to local spatial conditions, yielding an extra 35% energy savings compared to a single photosensor controlling all luminaires, and ensuring better delivery of target horizontal illuminance values across the space. Finally, we demonstrated a combination of local occupancy and daylight harvesting features that resulted in 79% energy savings compared to typical prevailing energy code provisions for open-plan offices.

Randomizing TCP payload size for TCP fairness in data center networks

As many-to-one traffic patterns prevail in data center networks, TCP flows often suffer from severe unfairness in sharing bottleneck bandwidth, which is known as the TCP outcast problem. The cause of the TCP outcast problem is the bursty packet losses by a drop-tail queue that triggers TCP timeouts and leads to decreasing the congestion window. This paper proposes TCPRand, a transport layer solution to TCP outcast. The main idea of TCPRand is the randomization of TCP payload size, which breaks synchronized packet arrivals between flows from different input ports. Based on the current congestion window size and the CUBIC’s congestion window growth function, TCPRand adaptively determines the proper level of randomness. With extensive ns-3 simulations and experiments, we show that TCPRand guarantees the superior enhancement of TCP fairness by reducing the TCP timeout period noticeably even in an environment where serious TCP outcast happens. TCPRand also minimizes the total goodput loss since its adaptive mechanism avoids unnecessary payload size randomization. Compared with DCTCP, TCPRand performs fairly well and only requires modification at the transport layer of the sender which makes its deployment relatively easier.