New Algorithms for Solving Tropical Linear Systems

The problem of solving tropical linear systems, a natural problem of tropical mathematics, has already proven to be very interesting from the algorithmic point of view: it is known to be in $NP\cap coNP$ but no polynomial time algorithm is known, although counterexamples for existing pseudopolynomial algorithms are (and have to be) very complex. In this work, we continue the study of algorithms for solving tropical linear systems. First, we present a new reformulation of Grigoriev's algorithm that brings it closer to the algorithm of Akian, Gaubert, and Guterman; this lets us formulate a whole family of new algorithms, and we present algorithms from this family for which no known superpolynomial counterexamples work. Second, we present a family of algorithms for solving overdetermined tropical systems. We show that for weakly overdetermined systems, there are polynomial algorithms in this family. We also present a concrete algorithm from this family that can solve a tropical linear system defined by an $m\times n$ matrix with maximal element $M$ in time $\Theta\left({m \choose n} \mathrm{poly}\left(m, n, \log M\right)\right)$, and this time matches the complexity of the best of previously known algorithms for feasibility testing.Comment: 17 page

Bounds on the number of connected components for tropical prevarieties

For a tropical prevariety in Rn given by a system of k tropical polynomials in n variables with degrees at most d, we prove that its number of connected components is less than k+7n−

Sudden To Adiabatic Transition in Beta Decay

We discuss effects in beta decays at very low beta energies, of the order of the kinetic energies of atomic electrons. As the beta energy is lowered the atomic response changes from sudden to adiabatic. As a consequence, the beta decay rate increases slightly and the ejection of atomic electrons (shake off) and subsequent production of X rays is turned off. We estimate the transition energy and the change in decay rate. The rate increase is largest in heavy atoms, which have a small Q value in their decay. The X ray switch-off is independent of Q value.Comment: 6 pages LaTe

Initiation of Psychotropic Medication after Partner Bereavement: A Matched Cohort Study

Background Recent changes to diagnostic criteria for depression in DSM-5 remove the bereavement exclusion, allowing earlier diagnosis following bereavement. Evaluation of the potential effect of this change requires an understanding of existing psychotropic medication prescribing by non-specialists after bereavement. Aims To describe initiation of psychotropic medication in the first year after partner bereavement. Methods In a UK primary care database, we identified 21,122 individuals aged 60 and over with partner bereavement and no psychotropic drug use in the previous year. Prescribing (anxiolytic/hypnotic, antidepressant, antipsychotic) after bereavement was compared to age, sex and practice matched controls. Results The risks of receiving a new psychotropic prescription within two and twelve months of bereavement were 9.5% (95% CI 9.1 to 9.9%) and 17.9% (17.3 to 18.4%) respectively; an excess risk of initiation in the first year of 12.4% compared to non-bereaved controls. Anxiolytic/hypnotic and antidepressant initiation rates were highest in the first two months. In this period, the hazard ratio for initiation of anxiolytics/hypnotics was 16.7 (95% CI 14.7 to 18.9) and for antidepressants was 5.6 (4.7 to 6.7) compared to non-bereaved controls. 13.3% of those started on anxiolytics/hypnotics within two months continued to receive this drug class at one year. The marked variation in background family practice prescribing of anxiolytics/hypnotics was the strongest determinant of their initiation in the first two months after bereavement. Conclusion Almost one in five older people received a new psychotropic drug prescription in the year after bereavement. The early increase and trend in antidepressant use after bereavement suggests some clinicians did not adhere to the bereavement exclusion, with implications for its recent removal in DSM-5. Family practice variation in use of anxiolytics/hypnotics suggests uncertainty over their role in bereavement with the potential for inappropriate long term use

Clinicians' perceptions of rationales for rehabilitative exercise in a critical care setting: A cross-sectional study

Australian College of Critical Care Nurses Ltd. Background: Rehabilitative exercise for critically ill patients may have many benefits; however, it is unknown what intensive care unit (ICU) clinicians perceive to be important rationale for the implementation of rehabilitative exercise in critical care settings. Objective: To identify which rationales for rehabilitative exercise interventions were perceived by ICU clinicians to be important and determine whether perceptions were consistent across nursing, medical and physiotherapy clinicians. Methods: A cross-sectional study was undertaken among clinicians (nursing, medical, physiotherapy) working in a mixed medical surgical ICU in an Australian metropolitan tertiary hospital. Participants completed a customised web-based questionnaire developed by a clinician working-group. The questionnaire consisted of 11 plausible rationales for commencing rehabilitative exercise in ICUs based on prior literature and their own clinical experiences grouped into 4 over-arching categories (musculoskeletal, respiratory, psychological and facilitation of discharge). Participants rated their perceived importance for each potential rationale on a 5-point Likert scale. Results: Participants (n = 76) with a median (interquartile range) 4.8 (1.5, 15.5) years of experience working in ICUs completed the questionnaire. Responses were consistent across professional disciplines. Clinicians rated rehabilitative exercise as either 'very much' or 'somewhat' important for facilitating discharge (n = 76, 100%), reducing muscle atrophy (n = 76, 100%), increasing muscle strength (n = 76, 100%), prevention of contractures (n = 73, 96%), reducing the incidence of ICU acquired weakness (n = 62, 82%), increasing oxygenation (n = 71, 93%), facilitating weaning (n = 72, 97%), reducing anxiety (n = 60, 80%), reducing depression (n = 64, 84%), reducing delirium (n = 53, 70%), and increasing mental alertness (n = 65, 87%). Conclusions: Any shortcoming in implementation of rehabilitation exercise is unlikely attributable to a lack of perceived importance by nursing, medical or physiotherapy clinicians who are the most likely clinicians to influence rehabilitation practices in ICUs. It is noteworthy that this study examined self-reported perceptions, not physiological or scientific legitimacy of rationales, or clinician behaviours in practice

Throughput Optimization with Latency Constraints

Modern datacenters are increasingly required to deal with latency-sensitive applications. A major question here is how to represent latency in desired objectives. Incorporation of multiple traffic characteristics (e.g., packet values and required processing requirements) significantly increases the complexity of buffer management policies. In this work, we consider weighted throughput optimization (total transmitted value) in the setting where every incoming packet is branded with intrinsic value, required processing, and slack (an offset from the arrival time when a packet should be transmitted), and the buffer is unbounded but effectively bounded by slacks. We introduce a number of algorithms based on priority queues and show that they are non-competitive; then we introduce a novel algorithm based on emulating a stack and prove a constant upper bound on its competitive ratio that tends to 3 as the slack-to-work ratio increases. We support our results with a comprehensive evaluation study on CAIDA network traces.TRUEpu

A systematic review of reviews on the prevalence of anxiety disorders in adult populations.

BACKGROUND: A fragmented research field exists on the prevalence of anxiety disorders. Here, we present the results of a systematic review of reviews on this topic. We included the highest quality studies to inform practice and policy on this issue. METHOD: Using PRISMA methodology, extensive electronic and manual citation searches were performed to identify relevant reviews. Screening, data extraction, and quality assessment were undertaken by two reviewers. Inclusion criteria consisted of systematic reviews or meta-analyses on the prevalence of anxiety disorders that fulfilled at least half of the AMSTAR quality criteria. RESULTS: We identified a total of 48 reviews and described the prevalence of anxiety across population subgroups and settings, as reported by these studies. Despite the high heterogeneity of prevalence estimates across primary studies, there was emerging and compelling evidence of substantial prevalence of anxiety disorders generally (3.8-25%), and particularly in women (5.2-8.7%); young adults (2.5-9.1%); people with chronic diseases (1.4-70%); and individuals from Euro/Anglo cultures (3.8-10.4%) versus individuals from Indo/Asian (2.8%), African (4.4%), Central/Eastern European (3.2%), North African/Middle Eastern (4.9%), and Ibero/Latin cultures (6.2%). CONCLUSIONS: The prevalence of anxiety disorders is high in population subgroups across the globe. Recent research has expanded its focus to Asian countries, an increasingly greater number of physical and psychiatric conditions, and traumatic events associated with anxiety. Further research on illness trajectories and anxiety levels pre- and post-treatment is needed. Few studies have been conducted in developing and under-developed parts of the world and have little representation in the global literature.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/brb3.497

Personal Insights on Three Research Directions in Networked Systems

In this work, we draw from our research and industry experience in the design of networked systems and define research directions that can simplify management and better exploit network infrastructure. We introduce problems both on data and control planes related to the design of a single network element and network-wide behaviors, concentrating on three directions: processing a single packet with packet classifiers, processing streams of packets in network switches, and network-wide control plane optimization. In particular, we consider efficient representations of packet classifiers, expressive implementations of buffer management policies, the composition of heterogeneous control planes, network virtualization, and extension of the network stack to support interactive applications. For the considered research directions outlined here, we formulate problems that, we believe, are important in the design of network systems. The purpose of this work is to attract system researchers to specific problems introduced in this paper.TRUEpu

Flexible visiting positively impacted on patients, families and staff in an Australian Intensive Care Unit: A before-after mixed method study

Background The admission of a relative to intensive care is stressful for families. To help them support the patient, families need assurance, information and an ability to be near their sick relative. Flexible visiting enables patient access but the impact of this on patients, families and staff is not clear. Objective To assess the impact of flexible visiting from the perspective of patients, families, and Intensive Care Unit (ICU) staff. Methods A before-after mixed method study was used with interviews, focus groups and surveys. Patients were interviewed, family members completed the Family Satisfaction in ICU survey and ICU staff completed a survey and participated in focus groups following the introduction of 21 h per day visiting in a tertiary ICU. The study was conducted within a philosophy of family-centred care. Results All interviewed patients (n = 12) positively evaluated the concept of extended visiting hours. Family members’ (n = 181) overall ‘satisfaction with care’ did not change; however 85% were ‘very satisfied’ with increased visiting flexibility. Seventy-six percent of family visits continued to occur within the previous visiting hours (11 am–8 pm) with the remaining 24% taking place during the newly available visiting hours. Families recognised the priority of patient care with their personal needs being secondary. Three-quarters of ICU staff were ‘satisfied’ with flexible visiting and suggested any barriers could be overcome by role modelling family inclusion. Conclusion Patients, families and ICU staff positively evaluated flexible visiting hours in this ICU. Although only a minority of families took advantage of the increased hours they indicated appreciation for the additional opportunities. Junior staff may benefit from peer-support to develop family inclusion skills. More flexible visiting times can be incorporated into usual ICU practice in a manner that is viewed positively by all stakeholders