2,520 research outputs found
Compositionality for Quantitative Specifications
We provide a framework for compositional and iterative design and verification of systems with quantitative information, such as rewards, time or energy. It is based on disjunctive modal transition systems where we allow actions to bear various types of quantitative information. Throughout the design process the actions can be further refined and the information made more precise. We show how to compute the results of standard operations on the systems, including the quotient (residual), which has not been previously considered for quantitative non-deterministic systems. Our quantitative framework has close connections to the modal nu-calculus and is compositional with respect to general notions of distances between systems and the standard operations
Influence of Anaesthesia on Mobilisation Following Hip Fracture Surgery : An Observational Study: 麻醉技術對髖部骨折病人術後活動能力的影響:一項觀察性研究
Background Anaesthetic technique can influence mortality and morbidity following hip fracture surgery. However, its influence on postoperative mobilisation is not clear. In this study, we evaluated the influence of anaesthetic technique on postoperative mobilisation. Methods In this prospective observational study, we included all consecutive patients who underwent surgery for hip fracture between 1 January 2012 and 31 December 2013 at our institution. Any patients who died prior to mobilisation or who could not be followed up after surgery were excluded. Data was collected on demographics, clinical characteristics, anaesthesia technique and surgical factors, and date and time of admission, operation, first mobilisation and discharge. Results Of the 1040 patients included in the analysis, 264 received general anaesthesia only (Group GA), 322 received general anaesthesia with regional anaesthesia (Group GARA), and 454 received central neuraxial blockade anaesthesia with or without sedation (Group CNB). There was no significant difference in age (p = 0.56), sex (p = 0.23), number of comorbidities (p = 0.06), residential status (p = 0.18), time to surgery (p = 0.10) and length of hospital stay (p = 0.30) between the three groups. There was a statistically significant difference in ASA grade (p = 0.01), implant type used (p = 0.04), grade of operating surgeon (p = 0.02) and grade of anaesthetist during surgery (p = 0.004) among the three groups. Patients in Group GARA had a median time-to-first mobilisation of 23.8 hours after surgery, compared to 24.1 hours in Group GA and 24.3 hours in Group CNB. This difference was not statistically significant after controlling for confounding factors (p = 0.45). Conclusion Our results show that anaesthetic technique does not influence time-to-first mobilisation after hip fracture surgery
Area characteristics, individual-level socioeconomic indicators, and smoking in young adults: the coronary artery disease risk development in young adults study
The 10-year follow-up examination in 1995-1996 to the population-based Coronary Artery Disease Risk Development in Young Adults Study was used to compare the strength with which socioeconomic indicators at the individual and area levels are related to smoking prevalence and to investigate contextual effects of area characteristics. When categories based on similar percentile cutoffs were compared, differences across area categories in the odds of smoking were smaller than differences across categories based on individual-level indicators. In Whites, there was evidence of a significant contextual effect of area characteristics on smoking: Living in the most disadvantaged area quartiles was associated with 50-110% higher odds of smoking, even after controlling for individual-level socioeconomic indicators. Clear contextual effects of area characteristics were not present in Blacks, but there was evidence that contextual effects may emerge at higher levels of individual-level socioeconomic position. Similar results were obtained for census tracts and block groups. Even in the presence of contextual effects, area measures may underestimate associations of individual-level variables with health outcomes. On the other hand, as illustrated by the presence of contextual effects, area- and individual-level measures are likely to tap into different constructs.http://deepblue.lib.umich.edu/bitstream/2027.42/78991/1/DiezRouxMerkin2003_AJE.pd
Area characteristics, individual-level socioeconomic indicators, and smoking in young adults: the coronary artery disease risk development in young adults study
The 10-year follow-up examination in 1995-1996 to the population-based Coronary Artery Disease Risk Development in Young Adults Study was used to compare the strength with which socioeconomic indicators at the individual and area levels are related to smoking prevalence and to investigate contextual effects of area characteristics. When categories based on similar percentile cutoffs were compared, differences across area categories in the odds of smoking were smaller than differences across categories based on individual-level indicators. In Whites, there was evidence of a significant contextual effect of area characteristics on smoking: Living in the most disadvantaged area quartiles was associated with 50-110% higher odds of smoking, even after controlling for individual-level socioeconomic indicators. Clear contextual effects of area characteristics were not present in Blacks, but there was evidence that contextual effects may emerge at higher levels of individual-level socioeconomic position. Similar results were obtained for census tracts and block groups. Even in the presence of contextual effects, area measures may underestimate associations of individual-level variables with health outcomes. On the other hand, as illustrated by the presence of contextual effects, area- and individual-level measures are likely to tap into different constructs.http://deepblue.lib.umich.edu/bitstream/2027.42/78991/1/DiezRouxMerkin2003_AJE.pd
Mechanisms driving variability in the ocean forcing of Pine Island Glacier
Pine Island Glacier (PIG) terminates in a rapidly melting ice shelf, and ocean circulation and temperature are implicated in the retreat and growing contribution to sea level rise of PIG and nearby glaciers. However, the variability of the ocean forcing of PIG has been poorly constrained due to a lack of multi-year observations. Here we show, using a unique record close to the Pine Island Ice Shelf (PIIS), that there is considerable oceanic variability at seasonal and interannual timescales, including a pronounced cold period from October 2011 to May 2013. This variability can be largely explained by two processes: cumulative ocean surface heat fluxes and sea ice formation close to PIIS; and interannual reversals in ocean currents and associated heat transport within Pine Island Bay, driven by a combination of local and remote forcing. Local atmospheric forcing therefore plays an important role in driving oceanic variability close to PIIS
Switching on the Lights for Gene Therapy
Strategies for non-invasive and quantitative imaging of gene expression in vivo have been developed over the past decade. Non-invasive assessment of the dynamics of gene regulation is of interest for the detection of endogenous disease-specific biological alterations (e.g., signal transduction) and for monitoring the induction and regulation of therapeutic genes (e.g., gene therapy). To demonstrate that non-invasive imaging of regulated expression of any type of gene after in vivo transduction by versatile vectors is feasible, we generated regulatable herpes simplex virus type 1 (HSV-1) amplicon vectors carrying hormone (mifepristone) or antibiotic (tetracycline) regulated promoters driving the proportional co-expression of two marker genes. Regulated gene expression was monitored by fluorescence microscopy in culture and by positron emission tomography (PET) or bioluminescence (BLI) in vivo. The induction levels evaluated in glioma models varied depending on the dose of inductor. With fluorescence microscopy and BLI being the tools for assessing gene expression in culture and animal models, and with PET being the technology for possible application in humans, the generated vectors may serve to non-invasively monitor the dynamics of any gene of interest which is proportionally co-expressed with the respective imaging marker gene in research applications aiming towards translation into clinical application
Probing strongly coupled anisotropic plasma
We calculate the static potential, the drag force and the jet quenching
parameter in strongly coupled anisotropic N=4 super Yang-Mills plasma. We find
that the jet quenching is in general enhanced in presence of anisotropy
compared to the isotropic case and that its value depends strongly on the
direction of the moving quark and the direction along which the momentum
broadening occurs. The jet quenching is strongly enhanced for a quark moving
along the anisotropic direction and momentum broadening happens along the
transverse one. The parameter gets lower for a quark moving along the
transverse direction and the momentum broadening considered along the
anisotropic one. Finally, a weaker enhancement is observed when the quark moves
in the transverse plane and the broadening occurs on the same plane. The drag
force for quark motion parallel to the anisotropy is always enhanced. For
motion in the transverse space the drag force is enhanced compared to the
isotropic case only for quarks having velocity above a critical value. Below
this critical value the force is decreased. Moreover, the drag force along the
anisotropic direction is always stronger than the force in the transverse
space. The diffusion time follows exactly the inverse relations of the drag
forces. The static potential is decreased and stronger decrease observed for
quark-antiquark pair aligned along the anisotropic direction than the
transverse one. We finally comment on our results and elaborate on their
similarities and differences with the weakly coupled plasmas.Comment: 1+44 pages, 18 Figures; Added results on static force; Added
references; version published in JHE
Variability in Basal Melting Beneath Pine Island Ice Shelf on Weekly to Monthly Timescales
Ocean-driven basal melting of Amundsen Sea ice shelves has triggered acceleration, thinning,
and grounding line retreat on many West Antarctic outlet glaciers. Here we present the first year-long
(2014) record of basal melt rate at sub-weekly resolution from a location on the outer Pine Island Ice Shelf.
Adjustment of the upper thermocline to local wind forced variability in the vertical Ekman velocity is the
dominant control on basal melting at weekly to monthly timescales. Atmosphere-ice-ocean surface heat
fluxes or changes in advection of modified Circumpolar Deep Water play no discernible role at these
timescales. We propose that during other years, a deepening of the thermocline in Pine Island Bay driven by
longer timescale processes may have suppressed the impact of local wind forcing on high-frequency
upper thermocline height variability and basal melting. This highlights the complex interplay between the
different processes and their timescales that set the basal melt rate beneath Pine Island Ice Shelf
Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors
Mammalian retinae have rod photoreceptors for night vision and cone photoreceptors for daylight and colour vision. For colour discrimination, most mammals possess two cone populations with two visual pigments (opsins) that have absorption maxima at short wavelengths (blue or ultraviolet light) and long wavelengths (green or red light). Microchiropteran bats, which use echolocation to navigate and forage in complete darkness, have long been considered to have pure rod retinae. Here we use opsin immunohistochemistry to show that two phyllostomid microbats, Glossophaga soricina and Carollia perspicillata, possess a significant population of cones and express two cone opsins, a shortwave-sensitive (S) opsin and a longwave-sensitive (L) opsin. A substantial population of cones expresses S opsin exclusively, whereas the other cones mostly coexpress L and S opsin. S opsin gene analysis suggests ultraviolet (UV, wavelengths <400 nm) sensitivity, and corneal electroretinogram recordings reveal an elevated sensitivity to UV light which is mediated by an S cone visual pigment. Therefore bats have retained the ancestral UV tuning of the S cone pigment. We conclude that bats have the prerequisite for daylight vision, dichromatic colour vision, and UV vision. For bats, the UV-sensitive cones may be advantageous for visual orientation at twilight, predator avoidance, and detection of UV-reflecting flowers for those that feed on nectar
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