525 research outputs found
Broadening of Plasmonic Resonance Due to Electron Collisions with Nanoparticle Boundary: Đ° Quantum Mechanical Consideration
We present a quantum mechanical approach to calculate broadening of plasmonic
resonances in metallic nanostructures due to collisions of electrons with the
surface of the structure. The approach is applicable if the characteristic size
of the structure is much larger than the de Broglie electron wavelength in the
metal. The approach can be used in studies of plasmonic properties of both
single nanoparticles and arrays of nanoparticles.Comment: 9 page
Insufficient protection by Neisseria meningitidis vaccination alone during eculizumab therapy
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Effectiveness of offloading interventions to heal foot ulcers in persons with diabetes: a systematic review
Background Offloading interventions are commonly used in clinical practice to heal foot ulcers. The aim of this updated systematic review is to investigate the effectiveness of offloading interventions to heal diabetic foot ulcers. Methods We updated our previous systematic review search of PubMed, EMBASE, and Cochrane databases to also include original studies published between July 29, 2014 and August 13, 2018 relating to four offloading intervention categories in populations with diabetic foot ulcers: (a) offloading devices, (b) footwear, (c) other offloading techniques, and (d) surgical offloading techniques. Outcomes included ulcer healing, plantar pressure, ambulatory activity, adherence, adverse events, patientâreported measures, and costâeffectiveness. Included controlled studies were assessed for methodological quality and had key data extracted into evidence and risk of bias tables. Included nonâcontrolled studies were summarised on a narrative basis. Results We identified 41 studies from our updated search for a total of 165 included studies. Six included studies were metaâanalyses, 26 randomised controlled trials (RCTs), 13 other controlled studies, and 120 nonâcontrolled studies. Five metaâanalyses and 12 RCTs provided highâquality evidence for nonâremovable kneeâhigh offloading devices being more effective than removable offloading devices and therapeutic footwear for healing plantar forefoot and midfoot ulcers. Total contact casts (TCCs) and nonâremovable kneeâhigh walkers were shown to be equally effective. Moderateâquality evidence exists for removable kneeâhigh and ankleâhigh offloading devices being equally effective in healing, but kneeâhigh devices have a larger effect on reducing plantar pressure and ambulatory activity. Lowâquality evidence exists for the use of felted foam and surgical offloading to promote healing of plantar forefoot and midfoot ulcers. Very limited evidence exists for the efficacy of any offloading intervention for healing plantar heel ulcers, nonâplantar ulcers, and neuropathic ulcers with infection or ischemia. Conclusion Strong evidence supports the use of nonâremovable kneeâhigh offloading devices (either TCC or nonâremovable walker) as the firstâchoice offloading intervention for healing plantar neuropathic forefoot and midfoot ulcers. Removable offloading devices, either kneeâhigh or ankleâhigh, are preferred as second choice over other offloading interventions. The evidence bases to support any other offloading intervention is still weak and more highâquality controlled studies are needed in these areas
Deep Inelastic Scattering in Conformal QCD
We consider the Regge limit of a CFT correlation function of two vector and
two scalar operators, as appropriate to study small-x deep inelastic scattering
in N=4 SYM or in QCD assuming approximate conformal symmetry. After clarifying
the nature of the Regge limit for a CFT correlator, we use its conformal
partial wave expansion to obtain an impact parameter representation encoding
the exchange of a spin j Reggeon for any value of the coupling constant. The
CFT impact parameter space is the three-dimensional hyperbolic space H3, which
is the impact parameter space for high energy scattering in the dual AdS space.
We determine the small-x structure functions associated to the exchange of a
Reggeon. We discuss unitarization from the point of view of scattering in AdS
and comment on the validity of the eikonal approximation.
We then focus on the weak coupling limit of the theory where the amplitude is
dominated by the exchange of the BFKL pomeron. Conformal invariance fixes the
form of the vector impact factor and its decomposition in transverse spin 0 and
spin 2 components. Our formalism reproduces exactly the general results predict
by the Regge theory, both for a scalar target and for gamma*-gamma* scattering.
We compute current impact factors for the specific examples of N=4 SYM and QCD,
obtaining very simple results. In the case of the R-current of N=4 SYM, we show
that the transverse spin 2 component vanishes. We conjecture that the impact
factors of all chiral primary operators of N=4 SYM only have components with 0
transverse spin.Comment: 44+16 pages, 7 figures. Some correction
Insulin-Stimulated Degradation of Apolipoprotein B100: Roles of Class II Phosphatidylinositol-3-Kinase and Autophagy
Both in humans and animal models, an acute increase in plasma insulin levels, typically following meals, leads to transient depression of hepatic secretion of very low density lipoproteins (VLDL). One contributing mechanism for the decrease in VLDL secretion is enhanced degradation of apolipoprotein B100 (apoB100), which is required for VLDL formation. Unlike the degradation of nascent apoB100, which occurs in the endoplasmic reticulum (ER), insulin-stimulated apoB100 degradation occurs post-ER and is inhibited by pan-phosphatidylinositol (PI)3-kinase inhibitors. It is unclear, however, which of the three classes of PI3-kinases is required for insulin-stimulated apoB100 degradation, as well as the proteolytic machinery underlying this response. Class III PI3-kinase is not activated by insulin, but the other two classes are. By using a class I-specific inhibitor and siRNA to the major class II isoform in liver, we now show that it is class II PI3-kinase that is required for insulin-stimulated apoB100 degradation in primary mouse hepatocytes. Because the insulin-stimulated process resembles other examples of apoB100 post-ER proteolysis mediated by autophagy, we hypothesized that the effects of insulin in autophagy-deficient mouse primary hepatocytes would be attenuated. Indeed, apoB100 degradation in response to insulin was significantly impaired in two types of autophagy-deficient hepatocytes. Together, our data demonstrate that insulin-stimulated apoB100 degradation in the liver requires both class II PI3-kinase activity and autophagy. © 2013 Andreo et al
Development of a perioperative medicine research agenda: a cross sectional survey
BACKGROUND: Post-operative complications are a significant source of morbidity and mortality for patients undergoing surgery. However, there is little research in the emerging field of perioperative medicine beyond cardiac risk stratification. We sought to determine the research priorities for perioperative medicine using a cross sectional survey of Canadian and American general internists. METHODS: Surveys were electronically sent to 312 general internists from the Canadian Society of Internal Medicine and 130 internists from the perioperative medicine research interest group within the US based Society of General Internal Medicine. The questionnaire contained thirty research questions and respondents were asked to rate the priority of these questions for future study. RESULTS: The research topics with the highest ratings included: the need for tight control of diabetes mellitus postoperatively and the value of starting aspirin on patients at increased risk for postoperative cardiac events. Research questions evaluating the efficacy and safety of perioperative interventions had higher ratings than questions relating to the prediction of postoperative risk. Questions relating to the yield of preoperative diagnostic tests had the lowest ratings (p < 0.001 for differences across these categories). CONCLUSION: The results of this survey suggest that practicing general internists believe that interventions studies are a priority within perioperative medicine. These findings should help prioritize research in this emerging field
An intervention program to reduce the number of hospitalizations of elderly patients in a primary care clinic
<p>Abstract</p> <p>Background</p> <p>The elderly population consumes a large share of medical resources in the western world. A significant portion of the expense is related to hospitalizations.</p> <p>Objectives</p> <p>To evaluate an intervention program designed to reduce the number of hospitalization of elderly patients by a more optimal allocation of resources in primary care.</p> <p>Methods</p> <p>A multidimensional intervention program was conducted that included the re-engineering of existing work processes with a focus on the management of patient problems, improving communication with outside agencies, and the establishment of a system to monitor quality of healthcare parameters. Data on the number of hospitalizations and their cost were compared before and after implementation of the intervention program.</p> <p>Results</p> <p>As a result of the intervention the mean expenditure per elderly patient was reduced by 22.5%. The adjusted number of hospitalizations/1,000 declined from 15.1 to 10.7 (29.3%). The number of adjusted hospitalization days dropped from 132 to 82 (37.9%) and the mean hospitalization stay declined from 8.2 to 6.7 days (17.9%). The adjusted hospitalization cost (32,574 to $18,624 (42.8%). The overall clinic expense, for all age groups, dropped by 9.9%.</p> <p>Conclusion</p> <p>Implementation of the intervention program in a single primary care clinic led to a reduction in hospitalizations for the elderly patient population and to a more optimal allocation of healthcare resources.</p
Double parton correlations and constituent quark models: a light front approach to the valence sector
An explicit evaluation of the double parton distribution functions (dPDFs), within a relativistic Light-Front approach to constituent quark models, is presented. dPDFs encode information on the correlations between two partons inside a target and represent the non-perturbative QCD ingredient for the description of double parton scattering in proton-proton collisions, a crucial issue in the search of new Physics at the LHC. Valence dPDFs are evaluated at the low scale of the model and the perturbative scale of the experiments is reached by means of QCD evolution. The present results show that the strong correlation effects present at the scale of the model are still sizable, in the valence region, at the experimental scale. At the low values of x presently studied at the LHC the correlations become less relevant, although they are still important for the spin-dependent contributions to unpolarized proton scattering
Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD
We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200â700 °C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as âĄSiâH monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures â„400 °C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap
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