On the Behavior of Hexane on Graphite at Near-Monolayer Densities

We present the results of molecular dynamics (MD) studies of hexane physisorbed onto graphite for eight coverages in the range $0.875 \le \rho \le 1.05$ (in units of monolayers). At low temperatures the adsorbate molecules form a uniaxially incommensurate herringbone (UI-HB) solid. At high coverages the solid consists of adsorbate molecules that are primarily rolled on their side perpen-dicular to the surface of the substrate. As the coverage is decreased, the amount of molecular rolling diminishes until $\rho$ = 0.933 where it disappears (molecules become primarily parallel to the surface). If the density is decreased enough, vacancies appear. As the temperature is increased we observe a three-phase regime for $\rho > 0.933$ (with an orientationally ordered nematic mesophase), for lower coverages the system melts directly to the disordered (and isotropic) liquid phase. The solid-nematic transition temperature is very sensitive to coverage whereas the melting temperature is quite insensitive to it, except for at low coverages where increased in-plane space and ultimately vacancies soften the solid phase and lower the melting temperature. Our results signal the importance of molecular rolling and tilting (which result from an the competition between molecule-molecule and molecule-substrate interactions) for the formation of the intermediate phase, while the insensitivity of the system's melting temperature to changing density is understood in terms of in-plane space occupation through rolling. Comparisons and contrasts with experimental results are discussed

Radiological staging in breast cancer: which asymptomatic patients to image and how.

BACKGROUND: Approximately 4% of patients diagnosed with early breast cancer have occult metastases at presentation. Current national and international guidelines lack consensus on whom to image and how. METHODS: We assessed practice in baseline radiological staging against local guidelines for asymptomatic newly diagnosed breast cancer patients presenting to the Cambridge Breast Unit over a 9-year period. RESULTS: A total of 2612 patients were eligible for analysis; 91.7% were appropriately investigated. However in the subset of lymph node negative stage II patients, only 269 out of 354 (76.0%) investigations were appropriate. No patients with stage 0 or I disease had metastases; only two patients (0.3%) with stage II and or =4 positive lymph nodes), III and IV disease, respectively. CONCLUSION: These results prompted us to propose new local guidelines for staging asymptomatic breast cancer patients: only clinical stage III or IV patients require baseline investigation. The high specificity and convenience of computed tomography (chest, abdomen and pelvis) led us to recommend this as the investigation of choice in breast cancer patients requiring radiological staging

Molecular-dynamics simulations of the dynamical excitations in commensurate submonolayer films of nitrogen molecules on graphite

URL:http://link.aps.org/doi/10.1103/PhysRevB.54.14077 DOI:10.1103/PhysRevB.54.14077The dynamics of commensurate submonolayer solids of N2 molecules adsorbed on the basal planes of graphite have been studied using molecular-dynamics simulations. The calculations yielded the temperature dependence of the Brillouin-zone-center gap in the acoustic-phonon branches, for comparison with inelastic neutron-scattering experiments on the submonolayer solid. The calculated frequency gap was the same in submonolayer and monolayer films at low temperatures. At intermediate temperatures, the diffusive molecular motion associated with the presence of vacancies caused the gap mode to be less clearly defined in the coherent scattering function. Diffusion constants are calculated at submonolayer coverages, and temperatures up to 40 K for a population of molecules identified as mobile.This work was partially supported by the National Science Foundation under Grant No. DMR-9314235 (H.T.) and Nos. DMR-9120199 and DMR-9423307 (L.W.B.) and by The Danish Natural Science Foundation (F.Y.H.). L.W.B. thanks the Fysisk-Kemisk Institut and the Technical University of Denmark for hospitality during the period this work was completed

Precision charging of microparticles in plasma via the Rayleigh instability for evaporating charged liquid droplets

In this paper we describe a novel method for delivering a precise, known amount of electric charge to a micron-sized solid target. Aerosolised microparticles passed through a plasma discharge will acquire significant electric charge. The fluid stability under evaporative stress is a key aspect that is core to the research. Initially stable charged aerosols subject to evaporation (i.e. a continually changing radius) may encounter the Rayleigh stability limit. This limit arises from the electrostatic and surface tension forces and determines the maximum charge a stable droplet can retain, as a function of radius. We demonstrate that even if the droplet charge is initially much less than the Rayleigh limit, the stability limit will be encountered as the droplet evaporates. The instability emission mechanism is strongly linked to the final charge deposited on the target, providing a mechanism that can be used to ensure a predictable charge deposit on a known encapsulated microparticle

It’s long-term, well it’s for life basically: Understanding and exploring the burden of immunoglobulin treatment in patients with primary immunodeficiency disorders

This paper describes the burden of receiving immunoglobulin (Ig) treatment from the perspective of patients diagnosed with a Primary Immunodeficiency (PID). Thirty semi-structured interviews with patients receiving intravenous (n=21) and subcutaneous immunoglobulin (n=9) therapy, either at home or in hospital were undertaken. Underpinned by a phenomenological theoretical framework, and using a qualitative, inductive thematic approach to prioritise patients’ concerns, we identified that Ig treatment requires considerable effort by the patient, particularly in relation to the amount of time, organization and planning that is needed. They also face numerous physical, social, relationship, emotional, role functioning, travelling, and financial challenges in their effort to undergo and maintain their infusions and care for their health. Some qualitative differences in treatment burden were noted between home and hospital settings which contributed to non-adherence to those regimes. Immunoglobulin treatment burden is complex and influenced by therapeutic mode and setting and the personal circumstances of the patient. As choice over treatment method appears to be mainly informed by lifestyle needs, PID patients may benefit from more information about these potential Ig lifestyle influences when selecting which form of treatment to take together with their health professional

Recent Salmon Declines: A Result of Lost Feeding Opportunities Due to Bad Timing?

As the timing of spring productivity blooms in near-shore areas advances due to warming trends in global climate, the selection pressures on out-migrating salmon smolts are shifting. Species and stocks that leave natal streams earlier may be favoured over later-migrating fish. The low post-release survival of hatchery fish during recent years may be in part due to static release times that do not take the timing of plankton blooms into account. This study examined the effects of release time on the migratory behaviour and survival of wild and hatchery-reared coho salmon (Oncorhynchus kisutch) using acoustic and coded-wire telemetry. Plankton monitoring and near-shore seining were also conducted to determine which habitat and food sources were favoured. Acoustic tags (n = 140) and coded-wire tags (n = 266,692) were implanted into coho salmon smolts at the Seymour and Quinsam Rivers, in British Columbia, Canada. Differences between wild and hatchery fish, and early and late releases were examined during the entire lifecycle. Physiological sampling was also carried out on 30 fish from each release group. The smolt-to-adult survival of coho salmon released during periods of high marine productivity was 1.5- to 3-fold greater than those released both before and after, and the fish's degree of smoltification affected their downstream migration time and duration of stay in the estuary. Therefore, hatchery managers should consider having smolts fully developed and ready for release during the peak of the near-shore plankton blooms. Monitoring chlorophyll a levels and water temperature early in the spring could provide a forecast of the timing of these blooms, giving hatcheries time to adjust their release schedule

Trace elements in hemodialysis patients: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Hemodialysis patients are at risk for deficiency of essential trace elements and excess of toxic trace elements, both of which can affect health. We conducted a systematic review to summarize existing literature on trace element status in hemodialysis patients.</p> <p>Methods</p> <p>All studies which reported relevant data for chronic hemodialysis patients and a healthy control population were eligible, regardless of language or publication status. We included studies which measured at least one of the following elements in whole blood, serum, or plasma: antimony, arsenic, boron, cadmium, chromium, cobalt, copper, fluorine, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, tellurium, thallium, vanadium, and zinc. We calculated differences between hemodialysis patients and controls using the differences in mean trace element level, divided by the pooled standard deviation.</p> <p>Results</p> <p>We identified 128 eligible studies. Available data suggested that levels of cadmium, chromium, copper, lead, and vanadium were higher and that levels of selenium, zinc and manganese were lower in hemodialysis patients, compared with controls. Pooled standard mean differences exceeded 0.8 standard deviation units (a large difference) higher than controls for cadmium, chromium, vanadium, and lower than controls for selenium, zinc, and manganese. No studies reported data on antimony, iodine, tellurium, and thallium concentrations.</p> <p>Conclusion</p> <p>Average blood levels of biologically important trace elements were substantially different in hemodialysis patients, compared with healthy controls. Since both deficiency and excess of trace elements are potentially harmful yet amenable to therapy, the hypothesis that trace element status influences the risk of adverse clinical outcomes is worthy of investigation.</p

Collision Resistant Hashing from Sub-exponential Learning Parity with Noise

The Learning Parity with Noise (LPN) problem has recently found many cryptographic applications such as authentication protocols, pseudorandom generators/functions and even asymmetric tasks including public-key encryption (PKE) schemes and oblivious transfer (OT) protocols. It however remains a long-standing open problem whether LPN implies collision resistant hash (CRH) functions. Based on the recent work of Applebaum et al. (ITCS 2017), we introduce a general framework for constructing CRH from LPN for various parameter choices. We show that, just to mention a few notable ones, under any of the following hardness assumptions (for the two most common variants of LPN) 1) constant-noise LPN is $2^{n^{0.5+\epsilon}}$-hard for any constant $\epsilon>0$; 2) constant-noise LPN is $2^{\Omega(n/\log n)}$-hard given $q=poly(n)$ samples; 3) low-noise LPN (of noise rate $1/\sqrt{n}$) is $2^{\Omega(\sqrt{n}/\log n)}$-hard given $q=poly(n)$ samples. there exists CRH functions with constant (or even poly-logarithmic) shrinkage, which can be implemented using polynomial-size depth-3 circuits with NOT, (unbounded fan-in) AND and XOR gates. Our technical route LPN$\rightarrow$bSVP$\rightarrow$CRH is reminiscent of the known reductions for the large-modulus analogue, i.e., LWE$\rightarrow$SIS$\rightarrow$CRH, where the binary Shortest Vector Problem (bSVP) was recently introduced by Applebaum et al. (ITCS 2017) that enables CRH in a similar manner to Ajtai\u27s CRH functions based on the Short Integer Solution (SIS) problem. Furthermore, under additional (arguably minimal) idealized assumptions such as small-domain random functions or random permutations (that trivially imply collision resistance), we still salvage a simple and elegant collision-resistance-preserving domain extender that is (asymptotically) more parallel and efficient than previously known. In particular, assume $2^{n^{0.5+\epsilon}}$-hard constant-noise LPN or $2^{n^{0.25+\epsilon}}$-hard low-noise LPN, we obtain a polynomially shrinking collision resistant hash function that evaluates in parallel only a single layer of small-domain random functions (or random permutations) and produces their XOR sum as output