COMPROF and COMPLACE : shared-memory communication profiling and automated thread placement via dynamic binary instrumentation

Funding: This work was generously supported by UK EPSRC Energise, grant number EP/V006290/1.This paper presents COMPROF and COMPLACE, a novel profiling tool and thread placement technique for shared-memory architectures that requires no recompilation or user intervention. We use dynamic binary instrumentation to intercept memory operations and estimate inter-thread communication overhead, deriving (and possibly visualising) a communication graph of data-sharing between threads. We then use this graph to map threads to cores in order to optimise memory traffic through the memory system. Different paths through a system's memory hierarchy have different latency, throughput and energy properties, COMPLACE exploits this heterogeneity to provide automatic performance and energy improvements for multi-threaded programs. We demonstrate COMPLACE on the NAS Parallel Benchmark (NPB) suite where, using our technique, we are able to achieve improvements of up to 12% in the execution time and up to 10% in the energy consumption (compared to default Linux scheduling) while not requiring any modification or recompilation of the application code.Postprin

Nocturnal light and temperature influences on necrophagous, carrion-associating blow fly species (Diptera: Calliphoridae) of forensic importance in Central Texas

It is commonly thought that blow flies are nocturnally inactive. Blowflies are often important in helping to estimate post mortem intervals (PMI) for corpses found at death scenes. If blow flies oviposit during nocturnal hours, there could possibly be up to 12-hour discrepancies for estimates of PMI. Two blow fly species, Phaenicia eximia (Wiedemann) and Cochliomyia macellaria (F.), oviposited nocturnally on ground beef baits in 2003, during the onset of low-atmospheric pressure (an air mass with lower atmospheric pressure than that of the air surrounding it) at rural study sites near Snook (Burleson County), Texas, under artificial lighting of at least 1500 footcandles when temperatures were at 26?C or higher. Trials conducted under similar conditions during the same year without a low-pressure system moving into the area resulted in no nocturnal blow fly oviposition. Nocturnal blow fly oviposition went undetected once low-atmospheric pressure systems settled into the study area, irrespective of temperature and lighting conditions. Thus, this study illustrates that there is a connection between the onset of low-atmospheric pressure and nocturnal blow fly oviposition on baits under artificial lighting of 1500 footcandles or more when temperatures are 26 ?C or above. After concluding 2003 experiments, statistical analyses supplied evidence that woodland habitat was more favorable for blow fly oviposition than prairieland habitat throughout the 2003 study, irrespective of species or time of year. Furthermore, statistical analyses conducted on nocturnal and diurnal temperature ranges furnished evidence to support the hypothesis that 2003 nocturnal temperatures had more of an effect on daily ovipositing than diurnal temperatures for P. eximia and Cynomyopsis cadaverina (Robineau-Desvoidy)

Rat Race: Insider Advice on Landing Judicial Clerkships

For many, the judicial clerkship application process is, to quote Sir Winston Churchill, a “riddle wrapped in a mystery inside an enigma.” It is a frenzied “Pamplona-like” atmosphere that begins on Labor Day +1 and continues unabated for several weeks. The initial week is the make or break point in the application review process because it is then that the judge starts to read each application and makes a “yes” or “no” evaluation. If his vote is a “no,” then no further action is taken. If it is a “yes,” the application passes to the law clerks, who then begin their evaluation. Our experience reviewing these applications has led us to the unanimous conclusion that many applicants select their list of judges and put together their packets with little or no thought of strategy as to how to get their applications past this initial phase and into the “yes” pile. We would like to guide the judicial clerkship applicant through the application process by discussing how our chambers conducts the interview and selection process. Specifically, we hope to dispel rumors of what goes on behind the curtain, and ultimately shed some light on how a clerkship applicant could improve his or her chances of receiving an offer. Although this article reflects the viewpoint of only one chambers, our collective experience is broad. Judge Ruggero J. Aldisert has been receiving law clerk applications, interviewing candidates and selecting clerks since 1961. From the standpoint of sheer experience in the law clerk selection process, Judge Aldisert must be near the top of the list of current federal appellate judges. His two present law clerks, Ryan Kirkpatrick and James Stevens, each wear two battle stars for action in the application process. Kirkpatrick and Stevens earned their first star in 2004 when they survived the initial post-Labor Day “running of the bulls,” a term which appropriately describes the federal judiciary’s present hiring plan. The two clerks earned their second star a year later when they closely examined each of the 200 applicants in the 2005 “stampede” and ultimately helped to select the two best candidates to go on to future honors. The authors are fully aware that there is a vast amount of literature discussing the clerkship application process. Most of the literature is couched in somber academic tomes, one of which was serious enough to require 334 footnotes. Our treatment of the subject is far less scholarly. We will not be discussing the role of game theory or the use of the “medical-matching model” in law clerk selection. Our purpose is simply to provide an insider’s perspective into the clerkship application process and, in doing so, defend the following theses: Unless you are the Editor-in-Chief of your school’s main law review or one of the top five or ten students in your class, you need to set yourself apart from the competition. Your road to success is through the face-to-face interview with the Judge. In making this point, we depart from the truism in the decision-making process that writing a good brief is more important than oral argument. In your written applications you may have sterling academic records, stunning extracurricular activities, and superb references, but whether you get the job offer depends on how you perform at the personal interview

Untimely illness:When diagnosis does not match age-related expectations

Background We explore the concept of “untimely diagnosis,” where the onset of a long-term condition occurs at a life stage which does not conform to traditional expectations, focusing on two conditions (asthma and arthritis) typically associated with a particular life stage (childhood and older adulthood, respectively). Previous literature has focused on the meaning of chronic illness in terms of life history, and the biographical lens has been used in various ways to make sense of the experience. Less attention has been paid to the condition onset when it seems dissonant with chronological age. Methods Secondary analysis of two qualitative data sets (total 58 interviews) exploring the experiences of people with adult-onset asthma and young people diagnosed with arthritis. Data from the original interview transcripts relating to diagnosis and symptom recognition were re-analysed using a “candidacy” framework to examine how age and diagnosis intersect. Results People did not always assert their candidacy for either condition because of pre-conceived expectations around age. Similarly, health professionals sometimes failed to recognize patients’ candidacy, instead pursuing “age-plausible” possibilities. In some cases, participants were proactive in suggesting a diagnosis to the health professional where diagnosis was delayed. Conclusion The diagnosis of adult-onset asthma, and arthritis in young people, may be regarded as “untimely.” We suggest that being diagnosed with what is perceived to be a “childhood” condition in adulthood, or “an older person's” condition in childhood, may be viewed as a “biographical paradox” and an “untimely breach” to the expected order

“…I’ve said I wish I was dead, you’d be better off without me”: a systematic review of people’s experiences of living with severe asthma

Objective: Our aim was to conduct a systematic review and synthesis of qualitative evidence exploring the lived experience of adults with severe asthma. Data sources: We searched MEDLINE via OvidSP, PsycINFO via OvidSP, PubMed, CINAHL, EMBASE, Sociological Abstracts, Google Scholar, the journals Qualitative Health Research and Qualitative Research, and a study of experiences of living with asthma by the Health Experiences Research group. Study selections: Studies were included if they used qualitative methods and explored the subjective experiences of adults (≥18 years) with a clear diagnosis of severe asthma. Results: From 575 identified studies, five met the inclusion criteria. Synthesis revealed an overarching theme of efforts that people living with severe asthma engage in to achieve personal control over their condition. Individuals ‘strive for autonomy’ through dealing with symptoms and treatment, acquiring knowledge, making decisions and reclaiming identity. Conclusion: This systematic review found a paucity of qualitative studies reporting on people's perspectives of living with severe asthma, and a focus on clinical rather than personal issues. Our synthesis reveals that severe asthma was disempowering, and a threat to identity and life roles. What was important to people living with severe asthma was striving to achieve a greater level of personal control over their condition, but these efforts received little support from their healthcare providers. Thus, more attention should be paid to understanding the self-management strategies and personal goals of people living with severe asthma. This may assist in designing interventions to better support patient self-management and improve health outcomes

A Candidate Dual Active Galactic Nucleus At Z=1.175

The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Bootes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0.''69 (5.5 kpc) in the spatial dimension and by 690 km s(-1) in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an active galactic nucleus (AGN) continuum, and the double-peaked profile resembles that of candidate dual AGNs. At a redshift of z = 1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 10(23) cm(-2). Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of similar to 10(45) erg s(-1). Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGNs following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates.National Science Foundation AST-0708490Strategic University Research Partnership ProgramNational Aeronautics and Space AdministrationW. M. Keck FoundationSmithsonian Astrophysical Observatory SV4-74018, A31Astronom

Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude

We present a sample of 17 newly discovered ultracool dwarf candidates later than ~M8, drawn from 231.90 arcmin2 of {\it Hubble Space Telescope} Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5<J_125<25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z_scl=290 +- 25 (random) +- 30 (systematic) pc for a binarity fraction of f_b=0. While our estimate is roughly consistent with published results, we suggest that the differences can be attributed to sample properties, with the present sample containing far more substellar objects than previous work. We predict the object counts should peak at J_{125}~24 AB mag due to the exponentially-declining number density at the edge of the disc. We conclude by arguing that trend in scale height with spectral type may breakdown for brown dwarfs since they do not settle onto the main sequence.Comment: 9 pages, 6 figures, 3 tables, accepted to ApJ (v2 is consistent with Referee changes

Accretion History of AGN II: Constraints on AGN Spectral Parameters using the Cosmic X-ray Background

We constrain X-ray spectral shapes for the ensemble of AGN based on the shape of the Cosmic X-ray Background (CXB). Specifically, we rule out regions of X-ray spectral parameter space that do not reproduce the CXB in the energy range 1-100 keV. The key X-ray spectral parameters are the photon index, {\Gamma}; the cutoff energy, Ecutoff; and the reflection scaling factor, R. Assuming each parameter follows a Gaussian distribution, we first explore the parameter space using a Bayesian approach and a fixed X-ray luminosity function (XLF). For {\sigma}_E = 36 keV and {\sigma}_R = 0.14, fixed at the observed values from the Swift-BAT 70-month sample, we allow , and to vary subject to reproducing the CXB. We report results for {\sigma}_{\Gamma} = 0.1-0.5. In an alternative approach, we define the parameter distributions, then forward model to fit the CXB by perturbing the XLF using a neural network. This approach allows us to rule out parameter combinations that cannot reproduce the CXB for any XLF. The marginalized conditional probabilities for the four free parameters are: = 0.99^{+0.11}_{-0.26}, = 118^{+24}_{-23}, {\sigma}_{\Gamma} = 0.101^{+0.097}_{-0.001} and = 1.9^{+0.08}_{-0.09}. We provide an interactive online tool for users to explore any combination of , {\sigma}_E, , {\sigma}_{\Gamma}, and {\sigma}_R including different distributions for each absorption bin, subject to the integral CXB constraint. The distributions observed in many AGN samples can be ruled out by our analysis, meaning these samples can not be representative of the full AGN population. The few samples that fall within the acceptable parameter space are hard X-ray-selected, commensurate with their having fewer selection biases.Comment: Accepted by ApJ, 15 pages, 7 figures and 3 table

Phase transition and landscape statistics of the number partitioning problem

The phase transition in the number partitioning problem (NPP), i.e., the transition from a region in the space of control parameters in which almost all instances have many solutions to a region in which almost all instances have no solution, is investigated by examining the energy landscape of this classic optimization problem. This is achieved by coding the information about the minimum energy paths connecting pairs of minima into a tree structure, termed a barrier tree, the leaves and internal nodes of which represent, respectively, the minima and the lowest energy saddles connecting those minima. Here we apply several measures of shape (balance and symmetry) as well as of branch lengths (barrier heights) to the barrier trees that result from the landscape of the NPP, aiming at identifying traces of the easy/hard transition. We find that it is not possible to tell the easy regime from the hard one by visual inspection of the trees or by measuring the barrier heights. Only the {\it difficulty} measure, given by the maximum value of the ratio between the barrier height and the energy surplus of local minima, succeeded in detecting traces of the phase transition in the tree. In adddition, we show that the barrier trees associated with the NPP are very similar to random trees, contrasting dramatically with trees associated with the $p$ spin-glass and random energy models. We also examine critically a recent conjecture on the equivalence between the NPP and a truncated random energy model