955 research outputs found
Synthesizing Imperative Programs from Examples Guided by Static Analysis
We present a novel algorithm that synthesizes imperative programs for
introductory programming courses. Given a set of input-output examples and a
partial program, our algorithm generates a complete program that is consistent
with every example. Our key idea is to combine enumerative program synthesis
and static analysis, which aggressively prunes out a large search space while
guaranteeing to find, if any, a correct solution. We have implemented our
algorithm in a tool, called SIMPL, and evaluated it on 30 problems used in
introductory programming courses. The results show that SIMPL is able to solve
the benchmark problems in 6.6 seconds on average.Comment: The paper is accepted in Static Analysis Symposium (SAS) '17. The
submission version is somewhat different from the version in arxiv. The final
version will be uploaded after the camera-ready version is read
Associations between e-cigarette access and smoking and drinking behaviours in teenagers
Background: Public health concerns regarding e-cigarettes and debate on appropriate regulatory responses are
focusing on the need to prevent child access to these devices. However, little is currently known about the
characteristics of those young people that are accessing e-cigarettes.
Methods: Using a cross-sectional survey of 14-17 year old school students in North West England (n = 16,193) we
examined associations between e-cigarette access and demographics, conventional smoking behaviours, alcohol
consumption, and methods of accessing cigarettes and alcohol. Access to e-cigarettes was identified through a
question asking students if they had ever tried or purchased e-cigarettes.
Results: One in five participants reported having accessed e-cigarettes (19.2%). Prevalence was highest among\ud
smokers (rising to 75.8% in those smoking >5 per day), although 15.8% of teenagers that had accessed e-cigarettes
had never smoked conventional cigarettes (v.13.6% being ex-smokers). E-cigarette access was independently
associated with male gender, having parents/guardians that smoke and students’ alcohol use. Compared with
non-drinkers, teenagers that drank alcohol at least weekly and binge drank were more likely to have accessed
e-cigarettes (adjusted odds ratio [AOR] 1.89, P < 0.001), with this association particularly strong among never-smokers
(AOR 4.59, P < 0.001). Among drinkers, e-cigarette access was related to: drinking to get drunk, alcohol-related violence,
consumption of spirits; self-purchase of alcohol from shops or supermarkets; and accessing alcohol by recruiting adult
proxy purchasers outside shops.
Conclusions: There is an urgent need for controls on the promotion and sale of e-cigarettes to children. Findings
suggest that e-cigarettes are being accessed by teenagers more for experimentation than smoking cessation. Those
most likely to access e-cigarettes may already be familiar with illicit methods of accessing age-restricted substances
Photonic mid-infrared nulling for exoplanet detection on a planar chalcogenide platform
The future of exoplanet detection lies in the mid-infrared (MIR). The MIR
region contains the blackbody peak of both hot and habitable zone exoplanets,
making the contrast between starlight and planet light less extreme. It is also
the region where prominent chemical signatures indicative of life exist, such
as ozone at 9.7 microns. At a wavelength of 4 microns the difference in
emission between an Earth-like planet and a star like our own is 80 dB. However
a jovian planet, at the same separation exhibits 60 dB of contrast, or only 20
dB if it is hot due to its formation energy or being close to its host star. A
two dimensional nulling interferometer, made with chalcogenide glass, has been
measured to produce a null of 20 dB, limited by scattered light. Measures to
increase the null depth to the theoretical limit of 60 dB are discussed.Comment: Was published in SPIE: Optical and Infrared Interferometry and
Imaging VI, Mike Ireland presente
Formation of ultra-compact X-ray binaries through circum-binary disk-driven mass transfer
The formation of ultra-compact X-ray binaries (UCXBs) has not been well
understood. Previous works show that ultra-short orbital periods ( hr) may
be reached through mass transfer driven by magnetic braking in normal
low/intermediate-mass X-ray binaries (L/IMXBs) only for an extremely small
range of initial binary parameters, which makes it difficult to account for the
rather large population of UCXBs. In this paper we report the calculated
results on mass transfer processes in L/IMXBs with a circum-binary disk. We
show that when the orbital angular momentum loss due to a circum-binary disk is
included, ultra-short orbital periods could be reached for a relatively wide
range of initial binary parameters. The results of our binary models suggest an
alternative formation channel for UCXBs.Comment: 25 pages, 8 figures, accepted for publication in Ap
Chalcogenide glass planar MIR couplers for future chip based Bracewell interferometers
Photonic integrated circuits are established as the technique of choice for a
number of astronomical processing functions due to their compactness, high
level of integration, low losses, and stability. Temperature control,
mechanical vibration and acoustic noise become controllable for such a device
enabling much more complex processing than can realistically be considered with
bulk optics. To date the benefits have mainly been at wavelengths around 1550
nm but in the important Mid-Infrared region, standard photonic chips absorb
light strongly. Chalcogenide glasses are well known for their transparency to
beyond 10000 nm, and the first results from coupler devices intended for use in
an interferometric nuller for exoplanetary observation in the Mid-Infrared L
band (3800-4200 nm) are presented here showing that suitable performance can be
obtained both theoretically and experimentally for the first fabricated devices
operating at 4000 nm.Comment: in Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging
V, 990730 (August 4, 2016
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Impact of the earthworm Lumbricus terrestris (L.) on As, Cu, Pb and Zn mobility and speciation in contaminated soils
To assess the risks that contaminated soils pose to the environment properly a greater understanding of how soil biota influence the mobility of metal(loid)s in soils is required. Lumbricus terrestris L. were incubated in three soils contaminated with As, Cu, Pb and Zn. The concentration and speciation of metal(loid)s in pore waters and the mobility and partitioning in casts were compared with earthworm-free soil. Generally the concentrations of water extractable metal(loid)s in earthworm casts were greater than in earthworm-free soil. The impact of the earthworms on concentration and speciation in pore waters was soil and metal specific and could be explained either by earthworm induced changes in soil pH or soluble organic carbon. The mobilisation of metal(loid)s in the environment by earthworm activity may allow for leaching or uptake into biota
Effects of acute fatigue on the volitional and magnetically-evoked electromechanical delay of the knee flexors in males and females
Neuromuscular performance capabilities, including those measured by evoked responses, may be adversely affected by fatigue; however, the capability of the neuromuscular system to initiate muscle force rapidly under these circumstances is yet to be established. Sex-differences in the acute responses of neuromuscular performance to exercise stress may be linked to evidence that females are much more vulnerable to ACL injury than males. Optimal functioning of the knee flexors is paramount to the dynamic stabilisation of the knee joint, therefore the aim of this investigation was to examine the effects of acute maximal intensity fatiguing exercise on the voluntary and magnetically-evoked electromechanical delay in the knee flexors of males and females. Knee flexor volitional and magnetically-evoked neuromuscular performance was assessed in seven male and nine females prior to and immediately after: (i) an intervention condition comprising a fatigue trial of 30-seconds maximal static exercise of the knee flexors, (ii) a control condition consisting of no exercise. The results showed that the fatigue intervention was associated with a substantive reduction in volitional peak force (PFV) that was greater in males compared to females (15.0%, 10.2%, respectively, p < 0.01) and impairment to volitional electromechanical delay (EMDV) in females exclusively (19.3%, p < 0.05). Similar improvements in magnetically-evoked electromechanical delay in males and females following fatigue (21%, p < 0.001), however, may suggest a vital facilitatory mechanism to overcome the effects of impaired voluntary capabilities, and a faster neuromuscular response that can be deployed during critical times to protect the joint system
Blockade of insulin-like growth factors increases efficacy of paclitaxel in metastatic breast cancer.
Breast cancer remains the leading cause of cancer death in women owing to metastasis and the development of resistance to established therapies. Macrophages are the most abundant immune cells in the breast tumor microenvironment and can both inhibit and support cancer progression. Thus, gaining a better understanding of how macrophages support cancer could lead to the development of more effective therapies. In this study, we find that breast cancer-associated macrophages express high levels of insulin-like growth factors 1 and 2 (IGFs) and are the main source of IGFs within both primary and metastatic tumors. In total, 75% of breast cancer patients show activation of insulin/IGF-1 receptor signaling and this correlates with increased macrophage infiltration and advanced tumor stage. In patients with invasive breast cancer, activation of Insulin/IGF-1 receptors increased to 87%. Blocking IGF in combination with paclitaxel, a chemotherapeutic agent commonly used to treat breast cancer, showed a significant reduction in tumor cell proliferation and lung metastasis in pre-clinical breast cancer models compared to paclitaxel monotherapy. Our findings provide the rationale for further developing the combination of paclitaxel with IGF blockers for the treatment of invasive breast cancer, and Insulin/IGF1R activation and IGF+ stroma cells as potential biomarker candidates for further evaluation
Expression profiling of metalloproteinases and tissue inhibitors of metalloproteinases in normal and degenerate human achilles tendon
To profile the messenger RNA (mRNA) expression for the 23 known genes of matrix metalloproteinases (MMPs), 19 genes of ADAMTS, 4 genes of tissue inhibitors of metalloproteinases (TIMPs), and ADAM genes 8, 10, 12, and 17 in normal, painful, and ruptured Achilles tendons. Tendon samples were obtained from cadavers or from patients undergoing surgical procedures to treat chronic painful tendinopathy or ruptured tendon. Total RNA was extracted and mRNA expression was analyzed by quantitative real-time reverse transcription–polymerase chain reaction, normalized to 18S ribosomal RNA. In comparing expression of all genes, the normal, painful, and ruptured Achilles tendon groups each had a distinct mRNA expression signature. Three mRNA were not detected and 14 showed no significant difference in expression levels between the groups. Statistically significant (P < 0.05) differences in mRNA expression, when adjusted for age, included lower levels of MMPs 3 and 10 and TIMP-3 and higher levels of ADAM-12 and MMP-23 in painful compared with normal tendons, and lower levels of MMPs 3 and 7 and TIMPs 2, 3, and 4 and higher levels of ADAMs 8 and 12, MMPs 1, 9, 19, and 25, and TIMP-1 in ruptured compared with normal tendons. The distinct mRNA profile of each tendon group suggests differences in extracellular proteolytic activity, which would affect the production and remodeling of the tendon extracellular matrix. Some proteolytic activities are implicated in the maintenance of normal tendon, while chronically painful tendons and ruptured tendons are shown to be distinct groups. These data will provide a foundation for further study of the role and activity of many of these enzymes that underlie the pathologic processes in the tendon
The strength of weight-bearing bones is similar in amenorrheic and eumenorrheic elite long-distance runners
Background: Regular intense endurance exercise can lead to amenorrhea with possible adverse consequences for bone health.
Objective: We compared whole-body and regional bone strength and skeletal muscle characteristics between amenorrheic (AA: n=14) and eumenorrheic (EA: n=15) elite adult female long distance runners and non-athletic controls (C: n=15).
Study design and Participants: Participants completed three-day food diaries, dual energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), peripheral quantitative computed tomography (pQCT) and isometric maximal voluntary knee extension contraction (MVC).
Results: Both athlete groups had a higher caloric intake than controls, with no significant difference between athlete groups. DXA revealed lower bone mineral density (BMD) at the trunk, rib, pelvis and lumbar spine in the AA than EA and C. pQCT showed greater bone size in the radius and tibia in EA and AA than C. The radius and tibia of AA had a larger endocortical circumference than C. Tibia bone mass and moments of inertia (Ix and Iy) were greater in AA and EA than C, whereas in the radius only the proximal Iy was larger in EA than C. Knee extensor MVC did not differ significantly between groups.
Conclusions: Amenorrheic adult female elite long-distance runners had lower BMD in the trunk, lumbar spine, ribs and pelvis than eumenorrheic athletes and controls. The radius and tibia bone size and strength indicators were similar in amenorrheic and eumenorrheic athletes, suggesting that long bones of the limbs differ in their response to amenorrhea from bones in the trunk
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