Decentralised Learning MACs for Collision-free Access in WLANs

By combining the features of CSMA and TDMA, fully decentralised WLAN MAC schemes have recently been proposed that converge to collision-free schedules. In this paper we describe a MAC with optimal long-run throughput that is almost decentralised. We then design two \changed{schemes} that are practically realisable, decentralised approximations of this optimal scheme and operate with different amounts of sensing information. We achieve this by (1) introducing learning algorithms that can substantially speed up convergence to collision free operation; (2) developing a decentralised schedule length adaptation scheme that provides long-run fair (uniform) access to the medium while maintaining collision-free access for arbitrary numbers of stations

Bringing home the trash: Do colony-based differences in foraging distribution lead to increased plastic ingestion in Laysan albatrosses?

When searching for prey, animals should maximize energetic gain, while minimizing energy expenditure by altering their movements relative to prey availability. However, with increasing amounts of marine debris, what once may have been ‘optimal’ foraging strategies for top marine predators, are leading to sub-optimal diets comprised in large part of plastic. Indeed, the highly vagile Laysan albatross (Phoebastria immutabilis) which forages throughout the North Pacific, are well known for their tendency to ingest plastic. Here we examine whether Laysan albatrosses nesting on Kure Atoll and Oahu Island, 2,150 km apart, experience different levels of plastic ingestion. Twenty two geolocators were deployed on breeding adults for up to two years. Regurgitated boluses of undigestable material were also collected from chicks at each site to compare the amount of plastic vs. natural foods. Chicks from Kure Atoll were fed almost ten times the amount of plastic compared to chicks from Oahu despite boluses from both colonies having similar amounts of natural food. Tracking data indicated that adults from either colony did not have core overlapping distributions during the early half of the breeding period and that adults from Kure had a greater overlap with the putative range of the Western Garbage Patch corroborating our observation of higher plastic loads at this colony. At-sea distributions also varied throughout the year suggesting that Laysan albatrosses either adjusted their foraging behavior according to constraints on time away from the nest or to variation in resources. However, in the non-breeding season, distributional overlap was greater indicating that the energy required to reach the foraging grounds was less important than the total energy available. These results demonstrate how a marine predator that is not dispersal limited alters its foraging strategy throughout the reproductive cycle to maximize energetic gain and how this has led to differences in plastic ingestion

The speckled scallop, Argopecten circularis, in Aqua Hedionda Lagoon, San Diego County, California

Speckled scallops, Argopecten circularis (Sowerby, 1835), were sampled at Agua Hedionda Lagoon, Carlsbad, San Diego County from March 1984 to October 1986, to obtain basic life history data. Monthly samples of scallops were collected, measured, and released to obtain length frequency data for estimates of growth, life span, and spawning period. Subsamples of scallops were collected for determination of gonadal-somatic and adductor muscle-somatic indices. In 1984 large concentrations of speckled scallops were found on the sand-silt bottom of the lagoon, closely associated with eelgrass, Zostra marina. During the course of the study the numbers of scallops declined, until their virtual disappearance at the end of 1986. Monthly length frequency plots from 24,375 scallop measurements indicate that this is a rapidly growing species with a short life span. Gonadal- and adductor muscle-somatic indices from subsamples of 1,714 scallops indicate first spawning at age one and a relationship between temperature and spawning. Based on this study management recommendations are made for the speckled scallop. (39pp.

Differences in Veterans' and Nonveterans' End-of-Life Preferences: A Pilot Study

Background: Investigators conducting focus groups on end-of-life preferences noted that veterans voiced opinions that strongly differed from those of nonveterans. Objective: The objective of this study was to further explore differences between veterans' and nonveterans' end-of-life preferences. Methods: Ten focus groups and a pilot survey were conducted. Setting and sample: The focus groups consisted of Arab Muslims, Arab Christians, Hispanics, blacks, and whites stratified by gender (n = 73). Fifteen male veterans were included across all five racial groups. Measures: A moderator discussion guide was used to lead the focus groups and a pilot survey asked about demographic information and end-of-life preferences. Results: Veterans were more likely to be married (p < 0.05) and less connected to their cultural group (p < 0.05) than nonveterans. The focus group results indicated that veterans in this study were more likely to oppose the use of heroic measures compared to nonveterans. More so than nonveterans, veterans felt that their doctors should be frank and open (p < 0.05) were strongly in favor of do-not-resuscitate (DNR) orders (p < 0.10), yet were less likely to have a proxy (p < 0.10) or durable power of attorney p < 0.01). Comparing end-of-life preferences, veterans felt less strongly than nonveterans about remembering personal accomplishments (p < 0.05), being listened to (p < 0.05), being with friends (p < 0.01), or being comfortable with their nurse (p < 0.05), but did want to be around their pets at the end of life p < 0.10). Implications: The Department of Veterans Affairs is in a unique position to improve endof- life care for veterans. Providing end-of-life care that is congruent with the veteran's wishes can improve satisfaction and increase cost effectiveness by eliminating unacceptable services.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63253/1/jpm.2006.9.1099.pd

Calcite Kinetics for Spiral Growth and Two-Dimensional Nucleation

Calcite crystals grow by means of molecular steps that develop on {10.4} faces. These steps can arise stochastically via two-dimensional (2D) nucleation or emerge steadily from dislocations to form spiral hillocks. Here, we determine the kinetics of these two growth mechanisms as a function of supersaturation. We show that calcite crystals larger than ∼1 μm favor spiral growth over 2D nucleation, irrespective of the supersaturation. Spirals prevail beyond this length scale because slow boundary layer diffusion creates a low surface supersaturation that favors the spiral mechanism. Sub-micron crystals favor 2D nucleation at high supersaturations, although diffusion can still limit the growth of nanoscopic crystals. Additives can change the dominant mechanism by impeding spiral growth or by directly promoting 2D nucleation

Disruption to Functional Networks in Neonates With Perinatal Brain Injury Predicts Motor Skills at 8 Months

Objective: Functional connectivity magnetic resonance imaging (fcMRI) of neonates with perinatal brain injury could improve prediction of motor impairment before symptoms manifest, and establish how early brain organization relates to subsequent development. This cohort study is the first to describe and quantitatively assess functional brain networks and their relation to later motor skills in neonates with a diverse range of perinatal brain injuries. Methods: Infants ( Results: Disruption to connectivity of the somatomotor and frontoparietal executive networks predicted motor impairment at 4 and 8 months. This disruption in functional connectivity was not found to be driven by differences between clinical groups, or by any of the specific measures we captured to describe the clinical course. Conclusion: fcMRI was predictive over and above other clinical measures available at discharge from the NICU, including structural MRI. Motor learning was affected by disruption to somatomotor networks, but also frontoparietal executive networks, which supports the functional importance of these networks in early development. Disruption to these two networks might be best addressed by distinct intervention strategies

Detecting sex-related changes to the metabolome of a critically endangered freshwater crayfish during the mating season

Captive breeding is a vital tool in the conservation of highly endangered species, as it is for the Margaret River hairy marron, Cherax tenuimanus, from the south west of Australia. A close relative, Cherax cainii, has almost completely displaced C. tenuimanus in the wild and is a successful aquaculture species, whereas C. tenuimanus has performed poorly in captivity. We used untargeted liquid chromatography-mass spectrometry to obtain metabolomic profiles of female and male C. tenuimanus held in controlled aquarium conditions during their reproductive period. Using repeated haemolymph sampling we tracked the metabolomic profiles of animals just prior to and for a period of up to 34 days after pairing with a similar sized potential mate. We identified 54 reproducible annotated metabolites including amino acids, fatty acids, biogenic amines, purine and pyrimidine metabolites and excretion metabolites. Hierarchical clustering analysis distinguished five metabolite clusters. Principal component-canonical variate analysis clearly distinguished females from males, both unpaired and paired; similar trends in profile changes in both sexes after pairing; and a striking shift in males upon pairing. We discuss three main patterns of metabolomic responses: differentiation between sexes; reactive responses to the disturbance of pairing; and convergent response to the disturbance of pairing for males. Females generally had higher concentrations of metabolites involved in metabolic rate, mobilisation of energy stores and stress. Responses to the disturbance of pairing were also related to elevated stress. Females were mobilising lipid stores to deposit yolk, whereas males had a rapid and strong response to pairing, with shifts in metabolites associated with gonad development and communication, indicating males could complete reproductive readiness only once paired with a female. The metabolomic profiles support a previously proposed potential mechanism for displacement of C. tenuimanus by C. cainii in the wild and identify several biomarkers for testing hypotheses regarding reproductive success using targeted metabolomics

Identification of a novel class of autotaxin inhibitors through cross-screening

Three novel series were generated in order to mimic the pharmacophoric features displayed by lead compound AM095, a Lysophosphatidic acid (LPA1) receptor antagonist. Biological evaluation of this array of putative LPA1 antagonists led us to the discovery of three novel series of inhibitors of the ecto-enzyme Autotaxin (ATX), responsible for LPA production in blood, with potencies in the range 1 – 4 μM accompanied with good (> 100 μg/mL) solubility

Opioid-Prescribing Practices for Post-Operative Patients in Otolaryngology: A Multiphasic Quality Improvement Project in a Single Large Institution

Objectives: In otolaryngology, postoperative pain management lacks evidence-based guidelines. We investigated opioid prescription and consumption for common procedures to develop prescribing guidelines at our institution. Study Design: Prospective, survey study. Methods: Patients who underwent surgery between July and September were given surveys upon discharge and at first follow-up visit. We assessed opioid usage and pain using the visual analog scale and opioid consumption throughout the postoperative period. Opioid prescriptions were converted to a standardized unit of 5 mg Oxycodone pills for reporting. Four procedures (transoral robotic surgery resection [TORS], sialendoscopy, parathyroidectomy/thyroidectomy, and parotidectomy) were selected for isolated analysis. Results: Of the 80 surveys that met criteria for inclusion for analysis, a total of 1,954.0 pills were prescribed, with 300.3 pills (15.4%) reported having been used by patients, leaving 1,653.7 pills (84.5%) unused. TORS (n=12) average pills used: 4.9 ± 5.9 (95% CI: 1.6-8.3); total % pills unused: 89.3%. Sialendoscopy (n=13) average pills used: 4.2 ± 5.1 (95% CI: 1.1-7.4); total % pills unused: 72.5%. Parathyroidectomy/thyroidectomy (n=22) average pills used: 3.1 ± 4.4 (95% CI: 1.7-5.5); total % pills unused: 79.2%. Parotidectomy (n=12) average pills used: 1.3 ± 2.5 (95% CI: 0.7-4.3); total % pills unused: 94.7%. Conclusions: At our institution, opioids for ((postoperative otolaryngology)) patients’ pain management in otolaryngologic procedures were prescribed in excess with 84.5% reported as unused. Procedure-specific opioid diversion pool ranged from 72.5%-94.7%. Our findings provide a foundation for procedure-specific evidence-based opioid prescription guidelines