9,351 research outputs found
Nonlinear instability of density-independent orbital-free kinetic energy functionals
We study in this article the mathematical properties of a class of
orbital-free kinetic energy functionals. We prove that these models are
linearly stable but nonlinearly unstable, in the sense that the corresponding
kinetic energy functionals are not bounded from below. As a matter of
illustration, we provide an example of an electronic density of simple shape
the kinetic energy of which is negative.Comment: 14 pages, 1 figur
Towards Low Cost Coupling Structures for Short-Distance Optical Interconnections
The performance of short distance optical interconnections in general relies
very strongly on coupling structures, since they will determine the overall
efficiency of the system to a large extent. Different configurations can be
considered and a variety of manufacturing technologies can be used. We present
two different discrete and two different integrated coupling components which
can be used to deflect the light beam over 90 degrees and can play a crucial
role when integrating optical interconnections in printed circuit boards. The
fabrication process of the different coupling structures is discussed and
experimental results are shown. The main characteristics of the coupling
structures are given. The main advantages and disadvantages of the different
components are discussed
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Optical Spectroscopy Of X-Ray Sources In The Extended Chandra Deep Field South
We present the first results of our optical spectroscopy program aimed to provide redshifts and identifications for the X-ray sources in the Extended Chandra Deep Field South. A total of 339 sources were targeted using the IMACS spectrograph at the Magellan telescopes and the VIMOS spectrograph at the VLT. We measured redshifts for 186 X-ray sources, including archival data and a literature search. We find that the active galactic nucleus (AGN) host galaxies have on average redder rest-frame optical colors than nonactive galaxies, and that they live mostly in the "green valley." The dependence of the fraction of AGNs that are obscured on both luminosity and redshift is confirmed at high significance and the observed AGN spatial density is compared with the expectations from existing luminosity functions. These AGNs show a significant difference in the mid-IR to X-ray flux ratio for obscured and unobscured AGNs, which can be explained by the effects of dust self-absorption on the former. This difference is larger for lower luminosity sources, which is consistent with the dust opening angle depending on AGN luminosity.National Aeronautics and Space Administration PF8-90055, NAS8-03060NSF AST0407295Spitzer JPL RSA1288440Natural Science and Engineering Research Council of Canada (NSERC)National Academy of SciencesNASA/INTEGRAL NNG05GM79GAstronom
Is standardized care feasible in the emergency setting? A case matched analysis of patients undergoing laparoscopic cholecystectomy.
Immediate laparoscopic cholecystectomy is the accepted standard for the treatment of acute cholecystitis. The aim of the present study was to evaluate the feasibility of a standardized approach with tailored care maps for pre- and postoperative care by comparing pain, nausea and patient satisfaction after elective and emergent laparoscopic cholecystectomy.
From January 2014 until April 2015, data on pain and nausea management were prospectively recorded for all elective and emergency procedures in the department of visceral surgery. This prospective observational study compared consecutive laparoscopic elective vs. emergency cholecystectomies. Visual analogue scales (VAS) were used to measure pain, nausea, and satisfaction from recovery room until 96 hours postoperatively.
Final analysis included 168 (79%) elective cholecystectomies and 44 (21%) emergent procedures. Demographics (Age, gender, BMI and ASA-scores) were comparable between the 2 groups. In the emergency group, patients did not receive anxiolytic medication (0% vs.13%, p = 0.009) and less postoperative nausea and vomiting (PONV) prophylaxis (77% vs. 97% p = <0.001). Perioperative pain management was similar in terms of opioid consumption (median amount of fentanyl 450ug [IQR 350-500] vs. 450ug [375-550], p = 0.456) and wound infiltration rates (24% vs. 25%, p = 0.799). Postoperative consumption of paracetamol, metamizole and opiod medications were similar between the 2 groups. VAS scores for pain (p = 0.191) and nausea (p = 0.392) were low for both groups. Patient satisfaction was equally high in both clinical settings (VAS 8.5 ± 1.1 vs. 8.6 ± 1.1, p = 0.68).
A standardized pathway allows equally successful control of pain and nausea after both elective and emergency laparoscopic cholecystectomy. This study was retrospectively registered by March 01, 2016 in the following trial register: www.researchregistry.com (UIN researchregistry993)
Primordial and primary prevention of peri-implant diseases: A systematic review and meta-analysis
Aim: This systematic review and meta-analysis aims to assess the efficacy of risk factor control to prevent the occurrence of peri-implant diseases (PIDs) in adult patients awaiting dental implant rehabilitation (primordial prevention) or in patients with dental implants surrounded by healthy peri-implant tissues (primary prevention). Materials and Methods: A literature search was performed without any time limit on different databases up to August 2022. Interventional and observational studies with at least 6 months of follow-up were considered. The occurrence of peri-implant mucositis and/or peri-implantitis was the primary outcome. Pooled data analyses were performed using random effect models according to the type of risk factor and outcome. Results: Overall, 48 studies were selected. None assessed the efficacy of primordial preventive interventions for PIDs. Indirect evidence on the primary prevention of PID indicated that diabetic patients with dental implants and good glycaemic control have a significantly lower risk of peri-implantitis (odds ratio [OR] = 0.16; 95% confidence interval [CI]: 0.03–0.96; I2: 0%), and lower marginal bone level (MBL) changes (OR = –0.36 mm; 95% CI: −0.65 to −0.07; I2: 95%) compared to diabetic patients with poor glycaemic control. Patients attending supportive periodontal/peri-implant care (SPC) regularly have a lower risk of overall PIDs (OR = 0.42; 95% CI: 0.24–0.75; I2: 57%) and peri-implantitis compared to irregular attendees. The risk of dental implant failure (OR = 3.76; 95% CI: 1.50–9.45; I2: 0%) appears to be greater under irregular or no SPC than regular SPC. Implants sites with augmented peri-implant keratinized mucosa (PIKM) show lower peri-implant inflammation (SMD = –1.18; 95% CI: −1.85 to −0.51; I2: 69%) and lower MBL changes (MD = –0.25; 95% CI: −0.45 to −0.05; I2: 62%) compared to dental implants with PIKM deficiency. Studies on smoking cessation and oral hygiene behaviors were inconclusive. Conclusions: Within the limitations of available evidence, the present findings indicate that in patients with diabetes, glycaemic control should be promoted to avoid peri-implantitis development. The primary prevention of peri-implantitis should involve regular SPC. PIKM augmentation procedures, where a PIKM deficiency exists, may favour the control of peri-implant inflammation and the stability of MBL. Further studies are needed to assess the impact of smoking cessation and oral hygiene behaviours, as well as the implementation of standardized primordial and primary prevention protocols for PIDs
Structure of worldwide populations of Lasioderma serricorne (Coleoptera: Anobiidae) as revealed by amplified fragment length polymorphism profiles
The cigarette beetle Lasioderma serricorne through transportation affects the infestation of stored tobacco. Using amplified fragment length polymorphism (AFLP), DNA polymorphisms were assessed in 16 populations of L. serricorne collected from 15 countries. The dendrograms constructed from profile distance matrices revealed well-supported colony clusters. There was no clear clustering as a function of the geographic origin of the samples. The results suggest extensive insect dispersal among geographical regions due to movement of infested commodities worldwide. This first AFLP population study of a stored-product insect demonstrates the potential of AFLP for distinguishing L. serricorne population
Pain Intensity in the First 96 Hours After Abdominal Surgery: A Prospective Cohort Study.
Multimodal pain management strategies aim to improve postoperative pain control. The purpose of this study was to analyze pain scores and risk factors for acute postoperative pain after various abdominal surgery procedures.
Data on 11 different abdominal surgery procedures were prospectively recorded. Pain intensity (rest, mobilization) and patient satisfaction at discharge were assessed using a visual analog scale (VAS; 0-10), and analgesic consumption was recorded until 96 hours postoperation. Demographic, surgery-related, and pain management-related univariate risk factors for insufficient pain control (VAS ≥ 4) were entered in a multivariate logistic regression model.
A total of 1,278 patients were included. Overall, mean VAS scores were <3 at all time points, and scores at mobilization were consistently higher than at rest (P < 0.05). Thirty percent of patients presented a prolonged VAS score ≥4 at mobilization at 24 hours, significantly higher than at rest (14%, P < 0.05). High pain scores correlated with high opioid consumption, whereas a variability of pain scores was observed in patients with low opioid consumption. The only independent risk factor for moderate and severe pain (VAS ≥ 4) was younger age (<70 years, P = 0.001). The mean satisfaction score was 8.18 ± 1.29.
Among 1,278 patients, pain was controlled adequately during the first four postoperative days, resulting in high levels of patient satisfaction. Pain levels were higher at mobilization. Younger age was the only independent risk factor for insufficient pain control. Preventive treatment in patients <70 years old and before mobilization could be evaluated for potential improvement
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