5,190 research outputs found
Plate-impact loading of cellular structures formed by selective laser melting
Porous materials are of great interest because of improved energy absorption over their solid counterparts. Their properties, however, have been difficult to optimize. Additive manufacturing has emerged as a potential technique to closely define the structure and properties of porous components, i.e. density, strut width and pore size; however, the behaviour of these materials at very high impact energies remains largely unexplored. We describe an initial study of the dynamic compression response of lattice materials fabricated through additive manufacturing. Lattices consisting of an array of intersecting stainless steel rods were fabricated into discs using selective laser melting. The resulting discs were impacted against solid stainless steel targets at velocities ranging from 300 to 700 m s-1 using a gas gun. Continuum CTH simulations were performed to identify key features in the measured wave profiles, while 3D simulations, in which the individual cells were modelled, revealed details of microscale deformation during collapse of the lattice structure. The validated computer models have been used to provide an understanding of the deformation processes in the cellular samples. The study supports the optimization of cellular structures for application as energy absorbers. © 2014 IOP Publishing Ltd
Following successful anti-leishmanial treatment, neutrophil counts, CD10 expression and phagocytic capacity remain reduced in visceral leishmaniasis patients co-infected with HIV
Visceral leishmaniasis (VL) patients co-infected with HIV (VL/HIV patients) experience frequent treatment failures, VL relapses, opportunistic infections, and higher mortality. Their immune system remains profoundly suppressed after clinical cure and they maintain higher parasite load. This is in contrast with patients with VL alone (VL patients). Since neutrophils play a critical role in the control of Leishmania replication and the regulation of immune responses, we tested the hypothesis that neutrophil activation status and effector functions are fully restored in VL, but not in VL/HIV patients. Our results show the neutrophil counts and all activation markers and effector functions tested in our study were reduced at the time of diagnosis in VL and VL/HIV patients as compared to controls. CD62L, CD63, arginase 1 expression levels and reactive oxygen species production were restored at the end of treatment in both groups. However, neutrophil counts, CD10 expression and phagocytosis remained significantly lower throughout follow-up in VL/HIV patients; suggesting that dysregulated neutrophils contribute to the impaired host defence against pathogens in VL/HIV patients
Mars oxygen production system design
The design and construction phase is summarized of the Mars oxygen demonstration project. The basic hardware required to produce oxygen from simulated Mars atmosphere was assembled and tested. Some design problems still remain with the sample collection and storage system. In addition, design and development of computer compatible data acquisition and control instrumentation is ongoing
Glasgow supported self-management trial (GSuST) for patients with moderate to severe COPD: randomised controlled trial
Objective To determine whether supported self management in chronic obstructive pulmonary disease (COPD) can reduce hospital readmissions in the United Kingdom
A photometricity and extinction monitor at the Apache Point Observatory
An unsupervised software ``robot'' that automatically and robustly reduces
and analyzes CCD observations of photometric standard stars is described. The
robot measures extinction coefficients and other photometric parameters in real
time and, more carefully, on the next day. It also reduces and analyzes data
from an all-sky camera to detect clouds; photometric data taken
during cloudy periods are automatically rejected. The robot reports its
findings back to observers and data analysts via the World-Wide Web. It can be
used to assess photometricity, and to build data on site conditions. The
robot's automated and uniform site monitoring represents a minimum standard for
any observing site with queue scheduling, a public data archive, or likely
participation in any future National Virtual Observatory.Comment: accepted for publication in A
Phases saturation control on mixing driven reactions in 3D porous media
Transported chemical reactions in unsaturated porous media are relevant
across a range of environmental and industrial applications. Continuum scale
dispersive models are often based on equivalent parameters derived from analogy
with saturated conditions, and cannot appropriately account for processes such
as incomplete mixing. It is also unclear how the third dimension controls
mixing and reactions in unsaturated conditions. We obtain 3 experimental
images of the phases distribution and of transported chemical reaction by
Magnetic Resonance Imaging (MRI) using an immiscible non-wetting liquid as a
second phase and a fast irreversible bimolecular reaction. Keeping the P\'eclet
number (Pe) constant, we study the impact of phases saturation on the dynamics
of mixing and the reaction front. By measuring the local concentration of the
reaction product, we quantify temporally resolved effective reaction rate
(). We describe the temporal evolution of using the lamellar theory of
mixing, which explains faster than Fickian () rate of product
formation by accounting for the deformation of mixing interface between the two
reacting fluids. For a given Pe, although stretching and folding of the
reactive front are enhanced as saturation decreases, enhancing the product
formation, this is larger as saturation increases, i.e., volume controlled.
After breakthrough, the extinction of the reaction takes longer as saturation
decreases because of the larger non-mixed volume behind the front. These
results are the basis for a general model to better predict reactive transport
in unsaturated porous media not achievable by the current continuum paradigm
Using Geospatial Information Technologies to Identify Factors Affecting Grazing Distribution on Grasslands
The relationship between environmental and management factors and grazing livestock distribution is fundamental to understanding and improving grazing systems. With the advent of geospatial information technologies, global positioning systems (GPS) and geographic information systems (GIS) have been used to improve the efficiency and effectiveness of quantifying the distribution of livestock grazing in response to various independent variables (Bailey et al., 2001). The specific objective of this project was to develop a tool that enables managers and students to identify and study the effect of management and environmental factors on grazing livestock distribution
Implications of a High Angular Resolution Image of the Sunyaev-Zel'dovich Effect in RXJ1347-1145
The most X-ray luminous cluster known, RXJ1347-1145 (z=0.45), has been the
object of extensive study across the electromagnetic spectrum. We have imaged
the Sunyaev-Zel'dovich Effect (SZE) at 90 GHz (3.3 mm) in RXJ1347-1145 at 10"
resolution with the 64-pixel MUSTANG bolometer array on the Green Bank
Telescope (GBT), confirming a previously reported strong, localized enhancement
of the SZE 20" to the South-East of the center of X-ray emission. This
enhancement of the SZE has been interpreted as shock-heated (> 20 keV) gas
caused by an ongoing major (low mass-ratio) merger event. Our data support this
interpretation. We also detect a pronounced asymmetry in the projected cluster
pressure profile, with the pressure just east of the cluster core ~1.6 times
higher than just to the west. This is the highest resolution image of the SZE
made to date.Comment: 9 pages, 7 figures; accepted for publication in The Astrophysical
Journa
The Death Detectives
The death detectives is a series of blogs about death, photography and seeing the crime written in partnership with The Photographers' Gallery and Surviving Work
Recommended from our members
Presyncope Is Associated with Intensive Care Unit Admission in Emergency Department Patients with Acute Pulmonary Embolism
Introduction: Syncope is common among emergency department (ED) patients with acute pulmonary embolism (PE) and indicates a higher acuity and worse prognosis than in patients without syncope. Whether presyncope carries the same prognostic implications has not been established. We compared incidence of intensive care unit (ICU) admission in three groups of ED PE patients: those with presyncope; syncope; and neither.Methods: This retrospective cohort study included all adults with acute, objectively confirmed PE in 21 community EDs from January 2013–April 2015. We combined electronic health record extraction with manual chart abstraction. We used chi-square test for univariate comparisons and performed multivariate analysis to evaluate associations between presyncope or syncope and ICU admission from the ED, reported as adjusted odds ratios (aOR) with 95% confidence intervals (CI).Results: Among 2996 PE patients, 82 (2.7%) had presyncope and 109 (3.6%) had syncope. ICU admission was similar between groups (presyncope 18.3% vs syncope 25.7%) and different than their non-syncope counterparts (either 22.5% vs neither 4.7%; p<0.0001). On multivariate analysis, both presyncope and syncope were independently associated with ICU admission, controlling for demographics, higher-risk PE Severity Index (PESI) class, ventilatory support, proximal clot location, and submassive and massive PE classification: presyncope, aOR 2.79 (95% CI, 1.40, 5.56); syncope, aOR 4.44 (95% CI 2.52, 7.80). These associations were only minimally affected when excluding massive PE from the model. There was no significant interaction between either syncope or presyncope and PESI, submassive or massive classification in predicting ICU admission.Conclusion: Presyncope appears to carry similar strength of association with ICU admission as syncope in ED patients with acute PE. If this is confirmed, clinicians evaluating patients with acute PE may benefit from including presyncope in their calculus of risk assessment and site-of-care decision-making
- …