394 research outputs found

    Modular termination verification for non-blocking concurrency

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    © Springer-Verlag Berlin Heidelberg 2016.We present Total-TaDA, a program logic for verifying the total correctness of concurrent programs: that such programs both terminate and produce the correct result. With Total-TaDA, we can specify constraints on a thread’s concurrent environment that are necessary to guarantee termination. This allows us to verify total correctness for nonblocking algorithms, e.g. a counter and a stack. Our specifications can express lock- and wait-freedom. More generally, they can express that one operation cannot impede the progress of another, a new non-blocking property we call non-impedance. Moreover, our approach is modular. We can verify the operations of a module independently, and build up modules on top of each other

    Gating-by-tilt of mechanosensitive membrane channels

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    We propose an alternative mechanism for the gating of biological membrane channels in response to membrane tension that involves a change in the slope of the membrane near the channel. Under biological membrane tensions we show that the energy difference between the closed (tilted) and open (untilted) states can far exceed kBT and is comparable to what is available under simple ilational gating. Recent experiments demonstrate that membrane leaflet asymmetries (spontaneous curvature) can strong effect the gating of some channels. Such a phenomenon would be more easy to explain under gating-by-tilt, given its novel intrinsic sensitivity to such asymmetry.Comment: 10 pages, 2 figure

    The transcriptional repressor protein NsrR senses nitric oxide directly via a [2Fe-2S] cluster

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    The regulatory protein NsrR, a member of the Rrf2 family of transcription repressors, is specifically dedicated to sensing nitric oxide (NO) in a variety of pathogenic and non-pathogenic bacteria. It has been proposed that NO directly modulates NsrR activity by interacting with a predicted [Fe-S] cluster in the NsrR protein, but no experimental evidence has been published to support this hypothesis. Here we report the purification of NsrR from the obligate aerobe Streptomyces coelicolor. We demonstrate using UV-visible, near UV CD and EPR spectroscopy that the protein contains an NO-sensitive [2Fe-2S] cluster when purified from E. coli. Upon exposure of NsrR to NO, the cluster is nitrosylated, which results in the loss of DNA binding activity as detected by bandshift assays. Removal of the [2Fe-2S] cluster to generate apo-NsrR also resulted in loss of DNA binding activity. This is the first demonstration that NsrR contains an NO-sensitive [2Fe-2S] cluster that is required for DNA binding activity

    Dust Devil Tracks

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    Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns

    Integrative medicine research at an academic medical center: patient characteristics and health-related quality-of-life outcomes.

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    OBJECTIVE: To characterize patients seeking care at a university-based integrative medicine practice, and to assess short-term changes in health-related quality of life (HRQoL) associated with integrative medical treatment. DESIGN: Prospective, observational study. SETTING: This study was conducted at a large U.S. academic medical center affiliated with the Consortium of Academic Health Centers for Integrative Medicine. PARTICIPANTS: Seven hundred and sixty-three (763) new patients with diverse medical conditions participated in the study. Mean age was 49 years (standard deviation = 16, range = 14-93). Two thirds of patients were women and three quarters were white. The most common International Classification of Diseases 9th Revision medical diagnoses were malaise and fatigue, myalgia and myositis, allergy, anxiety or depression, hypertension, malignant neoplasm of the breast, lumbago, and irritable bowel disease. Over half the sample had two or more comorbid medical conditions. OUTCOME MEASURE: The Medical Outcomes Study 36-item Short-Form (SF-36) health survey was used to measure HRQoL at initial assessment and 3-months following integrative medicine consultation. RESULTS: Baseline SF-36 scores fell below the 25th percentile, indicating substantially compromised HRQoL. Physician-prescribed treatment modalities included anthroposophical medicine, nutritional medicine, Western herbs, homeopathy, nutritional counseling, and acupuncture. Three (3) month follow-up assessment revealed statistically significant improvements on all eight SF-36 subscales among survey respondents. HRQoL effect sizes ranged from 0.17 (Physical Functioning) to 0.41 (Social Functioning), with a mean of 0.30. HRQoL effects were consistent among demographic subgroups. CONCLUSIONS: Integrative medical treatment at a university-based center is associated with significant increases in HRQoL for a medically diverse population with substantial comorbidity and functional limitations. Controlled studies that measure HRQoL and additional outcomes related to whole person health--physical, mental, social, and spiritual--are needed to determine the full therapeutic potential of integrative medicine, and to determine efficacy and cost-effectiveness relative to conventional medical care

    MAPK-dependent regulation of IL-1- and β-adrenoreceptor-induced inflammatory cytokine production from mast cells: Implications for the stress response

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    BACKGROUND: Catecholamines, such as epinephrine, are elaborated in stress responses, and mediate vasoconstriction to cause elevation in systemic vascular resistance and blood pressure. Our previous study has shown that IL-1 can induce mast cells to produce proinflammatory cytokines which are involved in atherogenesis. The aim of this study was to determine the effects of epinephrine on IL-1-induced proatherogenic cytokine production from mast cells. RESULTS: Two ml of HMC-1 (0.75 × 10(6 )cells/ml) were cultured with epinephrine (1 × 10(-5 )M) in the presence or absence of IL-1β (10 ng/ml) for 24 hrs. HMC-1 cultured alone produced none to trace amounts of IL-6, IL-8, and IL-13. IL-1β significantly induced production of these cytokines in HMC-1, while epinephrine alone did not. However, IL-6, IL-8, and IL-13 production induced by IL-1β were significantly enhanced by addition of epinephrine. The enhancing effect appears to involve NF-κB and p38 MAPK pathways. Flow cytometry showed the presence of β(1 )and β(2 )adrenoreceptors on resting mast cells. The enhancing effect of proatherogenic cytokine production by epinephrine was down regulated by the β(1 )and β(2 )adrenoceptor antagonist, propranolol, but not by the β(1 )adrenoceptor antagonist, atenolol, suggesting the effect involved β(2 )adrenoceptors. The enhancing effect of epinephrine on proatherogenic cytokine production was also down regulated by the immunosuppressive drug, dexamethasone. CONCLUSIONS: These results not only confirm that an acute phase cytokine, IL-1β, regulates mast cell function, but also show that epinephrine up regulates the IL-1β induction of proatherogenic cytokines in mast cells. These data provide a novel role for epinephrine, a stress hormone, in inflammation and atherogenesis

    MAPK-Dependent Regulation of IL-1-and β-Adrenoreceptor-Induced Inflammatory Cytokine Production From Mast Cells: Implications for the Stress Response

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    Background: Catecholamines, such as epinephrine, are elaborated in stress responses, and mediate vasoconstriction to cause elevation in systemic vascular resistance and blood pressure. Our previous study has shown that IL-1 can induce mast cells to produce proinflammatory cytokines which are involved in atherogenesis. The aim of this study was to determine the effects of epinephrine on IL-1-induced proatherogenic cytokine production from mast cells. Results: Two ml of HMC-1 (0.75 × 106 cells/ml) were cultured with epinephrine (1 × 10-5 M) in the presence or absence of IL-1β (10 ng/ml) for 24 hrs. HMC-1 cultured alone produced none to trace amounts of IL-6, IL-8, and IL-13. IL-1β significantly induced production of these cytokines in HMC-1, while epinephrine alone did not. However, IL-6, IL-8, and IL-13 production induced by IL-1β were significantly enhanced by addition of epinephrine. The enhancing effect appears to involve NF-κB and p38 MAPK pathways. Flow cytometry showed the presence of β1 and β2 adrenoreceptors on resting mast cells. The enhancing effect of proatherogenic cytokine production by epinephrine was down regulated by the β1 and β2 adrenoceptor antagonist, propranolol, but not by the β1 adrenoceptor antagonist, atenolol, suggesting the effect involved β2 adrenoceptors. The enhancing effect of epinephrine on proatherogenic cytokine production was also down regulated by the immunosuppressive drug, dexamethasone. Conclusions: These results not only confirm that an acute phase cytokine, IL-1β, regulates mast cell function, but also show that epinephrine up regulates the IL-1β induction of proatherogenic cytokines in mast cells. These data provide a novel role for epinephrine, a stress hormone, in inflammation and atherogenesis

    Cost-Comparison of Two Trabecular Micro-Bypass Stents Versus Selective Laser Trabeculoplasty or Medications Only for Intraocular Pressure Control for Patients with Open-Angle Glaucoma

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    Aim: Patients with open-angle glaucoma (OAG) whose intraocular pressure is not adequately controlled by one medication have several treatment options in the US. This analysis evaluated direct costs of unilateral eye treatment with two trabecular micro-bypass stents (two iStents) compared to selective laser trabeculoplasty (SLT) or medications only. Materials and methods: A population-based, annual state-transition, probabilistic, cost-of-care model was used to assess OAG-related costs over 5 years. Patients were modeled to initiate treatment in year zero with two iStents, SLT, or medications only. In years 1–5, patients could remain on initial treatment or move to another treatment option(s), or filtration surgery. Treatment strategy change probabilities were identified by a clinician panel. Direct costs were included for drugs, procedures, and complications. Results: The projected average cumulative cost at 5 years was lower in the two-stent treatment arm (4,420)comparedtotheSLTarm(4,420) compared to the SLT arm (4,730) or medications-only arm (6,217).InitialyearzerocostswerehigherwithtwoiStents(6,217). Initial year-zero costs were higher with two iStents (2,810) than with SLT (842)ormedicationsonly(842) or medications only (996). Average marginal annual costs in years 1–5 were 322fortwoiStents,322 for two iStents, 777 for SLT, and 1,044formedicationsonly.ThecumulativecostdifferencesbetweentwoiStentsvsSLTormedicationsonlydecreasedovertime,withbreakevenby5or3yearspostinitiation,respectively.Byyear5,cumulativesavingswithtwoiStentsoverSLTormedicationsonlywas1,044 for medications only. The cumulative cost differences between two iStents vs SLT or medications only decreased over time, with breakeven by 5 or 3 years post-initiation, respectively. By year 5, cumulative savings with two iStents over SLT or medications only was 309 or $1,797, respectively. Limitations: This analysis relies on clinical expert panel opinion and would benefit from real-world evidence on use of multiple procedures and treatment switching after two-stent treatment, SLT, or polypharmaceutical initial approaches. Conclusions: Despite higher costs in year zero, annual costs thereafter were lowest in the two-stent treatment arm. Two-stent treatment may reduce OAG-related health resource use, leading to direct savings, especially over medications only or at longer time horizons
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