7,771 research outputs found
Value added or misattributed? A multi-institution study on the educational benefit of labs for reinforcing physics content
Instructional labs are widely seen as a unique, albeit expensive, way to
teach scientific content. We measured the effectiveness of introductory lab
courses at achieving this educational goal across nine different lab courses at
three very different institutions. These institutions and courses encompassed a
broad range of student populations and instructional styles. The nine courses
studied had two key things in common: the labs aimed to reinforce the content
presented in lectures, and the labs were optional. By comparing the performance
of students who did and did not take the labs (with careful normalization for
selection effects), we found universally and precisely no added value to
learning from taking the labs as measured by course exam performance. This work
should motivate institutions and departments to reexamine the goals and conduct
of their lab courses, given their resource-intensive nature. We show why these
results make sense when looking at the comparative mental processes of students
involved in research and instructional labs, and offer alternative goals and
instructional approaches that would make lab courses more educationally
valuable.Comment: Accepted to Phys Rev PE
Inelastic scattering in a local polaron model with quadratic coupling to bosons
We calculate the inelastic scattering probabilities in the wide band limit of
a local polaron model with quadratic coupling to bosons. The central object is
a two-particle Green function which is calculated exactly using a purely
algebraic approach. Compared with the usual linear interaction term a quadratic
interaction term gives higher probabilities for inelastic scattering involving
a large number of bosons. As an application we consider the problem hot
electron mediated energy transfer at surfaces and use the delta self-consistent
field extension of density functional theory to calculate and compare coupling
parameters and probabilities for exciting different vibrational modes of CO
adsorbed on a Cu(100) surface
Simulation and Control of an Anti-Swing System for a Suspended Load attached to a moving Base Robot
Master's thesis Mechatronics MAS500 - University of Agder 2018Advanced motion compensation is an important eld of engineering in today's o shore
industry. Performing advanced load handling operations at sea requires high attention to
both safety and e ciency. In environments governed by wave motion and harsh weather
conditions, these types of operations are complex tasks. Most of the load handling scenarios
are performed by advanced o shore loader cranes, where many of these are equipped with
the industry's state-of-the-art Active Heave Compensation. This technology is capable of
compensating for the wave height disturbance, meaning that the load is kept at a constant
height above the sea oor. A common problem arises when equipment or personnel have
to be transported from a moving vessel to another vessel or o shore installation. In these
scenarios compensation of the side-to-side motion is of equal importance as the relative
height movement.
This thesis proposes a method to reduce this side-ways motion. An anti-swing system has
been developed for a simulation model of a suspended load attached to a moving base
robot. The work focuses on deriving mathematical models of the related systems, where
control systems are designed to the reduce the swing motion of the suspended load by
actuation of the load handling robot. The developed system models are based on the
available equipment of the Norwegian Motion-Laboratory. Results of the proposed system
are obtained from the simulation of the motion system, which yields a system capable of
tracking the robotic tool-point reference signal with acceptable accuracy and reducing the
suspended load's swing-angles with satisfactory performance
RIPK3 restricts viral pathogenesis via cell death-independent neuroinflammation
Receptor-interacting protein kinase-3 (RIPK3) is an activator of necroptotic cell death, but recent work has implicated additional roles for RIPK3 in inflammatory signaling independent of cell death. However, while necroptosis has been shown to contribute to antiviral immunity, death-independent roles for RIPK3 in host defense have not been demonstrated. Using a mouse model of West Nile virus (WNV) encephalitis, we show that RIPK3 restricts WNV pathogenesis independently of cell death. Ripk3(-/-) mice exhibited enhanced mortality compared to wild-type (WT) controls, while mice lacking the necroptotic effector MLKL, or both MLKL and caspase-8, were unaffected. The enhanced susceptibility of Ripk3(-/-) mice arose from suppressed neuronal chemokine expression and decreased central nervous system (CNS) recruitment of T lymphocytes and inflammatory myeloid cells, while peripheral immunity remained intact. These data identify pleiotropic functions for RIPK3 in the restriction of viral pathogenesis and implicate RIPK3 as a key coordinator of immune responses within the CNS
Tailored for Real-World: A Whole Slide Image Classification System Validated on Uncurated Multi-Site Data Emulating the Prospective Pathology Workload.
Standard of care diagnostic procedure for suspected skin cancer is microscopic examination of hematoxylin & eosin stained tissue by a pathologist. Areas of high inter-pathologist discordance and rising biopsy rates necessitate higher efficiency and diagnostic reproducibility. We present and validate a deep learning system which classifies digitized dermatopathology slides into 4 categories. The system is developed using 5,070 images from a single lab, and tested on an uncurated set of 13,537 images from 3 test labs, using whole slide scanners manufactured by 3 different vendors. The system\u27s use of deep-learning-based confidence scoring as a criterion to consider the result as accurate yields an accuracy of up to 98%, and makes it adoptable in a real-world setting. Without confidence scoring, the system achieved an accuracy of 78%. We anticipate that our deep learning system will serve as a foundation enabling faster diagnosis of skin cancer, identification of cases for specialist review, and targeted diagnostic classifications
Kinetics of toluene degradation by toluene-oxidizing bacteria as a function of oxygen concentration, and the effect of nitrate
The kinetics of toluene degradation as a function of oxygen concentration were compared for six strains of toluene-oxidizing bacteria using initial rate assays. The effect of nitrate was also examined. Rates of degradation and the relative effect of oxygen on the degradation rate were correlated with the pathway for toluene oxidation. Strains which synthesize toluene dioxygenases, Pseudomonas putida F1, P. fluorescens CFS215, and Pseudomonas sp. strain W31, degraded toluene at significantly higher rates (151â166 nmol/mg per min) than strains synthesizing toluene monooxygenases, Burkholderia cepacia G4 (23 nmol/mg per min) and B. pickettii PKO1 (14 nmol/mg per min), or a methylmonooxygenase, P. putida PaW1 (12 nmol/mg per min). Rates declined 30â48% for the dioxygenase strains and 25% for PaW1 as the oxygen concentration was decreased from 240 to 50 ÎM, but declined less than 10% for G4 and PKO1. Nitrate enhanced toluene degradation by the denitrifying strains PKO1 and W31 at oxygen concentrations below 30 ÎM, but had no significant effect on any of the other strains. Biphasic kinetics were observed for all of the strains, with double-reciprocal plots of the data exhibiting an inflection point at a âcritical oxygen concentrationâ between 20 and 30 ÎM. Below this concentration, the rate of toluene degradation was inhibited to a greater extent than predicted by the kinetic data for higher oxygen concentrations. For the denitrifying strains PKO1 and W31, however, monophasic kinetics were observed when nitrate was provided as an alternative electron acceptor. These observations suggest that biphasic kinetics result when rates of toluene degradation are limited by the availability of electron acceptor at the critical oxygen concentration, and that this limitation is overcome by denitrifying strains able to respire nitrate. Taken together, our findings suggest that the synthesis of monooxygenases and the ability to denitrify represent independent adaptations for toluene utilization in low oxygen environments. Moreover, these data support the use of nitrate in mixed electron acceptor strategies for the bioremediation of contaminated aquifers, as well as the targeted use of monooxygenase and dioxygenase strains in settings in which their physiological traits can be best exploited.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74870/1/j.1574-6941.1997.tb00387.x.pd
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The challenges of COVID-19 for people with dementia with Lewy bodies and family caregivers.
Introduction
During the current SARS-CoV-2 pandemic dementia has been identified as disproportionally common in adults aged over 65 who develop severe COVID-19.1 Observational data from the International Severe Acute Respiratory and Emerging Infections Consortium also confirms a high prevalence of dementia in older adults hospitalised with COVID-19.2 It is so far unclear whether there is any direct effect of dementia pathologies as dementia is a disease of old age, and thus likely to be associated with a variety of comorbidities, in particular, frailty, which may further exacerbate the risk of severe infection. In addition up to one third of COVID patients have demonstrated neurological sequelae3 and there may be both direct (viral infection within the brain, vascular effects) and indirect effects (e.g. host immunological response, impact of treatment) of SARS-CoV-2 on the brain.4 It is therefore possible that SARS-CoV-2 infection may accentuate any pre-existing neurodegenerative disease
Two-and-a-half-year clinical experience with the world\u27s first magnetic resonance image guided radiation therapy system
Strength and conditioning practices in rowing
There is limited published research on the practices of strength and conditioning (S &C) coaches in Great Britain. Information about training program design would be useful in developing models of good practice and ecologically valid intervention studies. The aim of this research was to quantify the training practices of coaches responsible for the S&C of rowing athletes. A questionnaire was developed that consisted of 6 sections: (a) personal details, (b) physical testing, (c) strength and power development, (d) flexibility development, (e) unique aspects of the program, and (f) any further relevant comments regarding the athletes prescribed training program. Twenty-two rowing and 10 S&C coaches with an average of 10.5 ± 7.2 years' experience agreed to complete the questionnaire. Approximately, 34% coached rowers of Olympic standard, 34% coached national standard, 3% coached regional standard, 19% coached club standard, and 10% coached university standard rowers. All coaches agreed that strength training enhanced rowing performance and the majority (74%) indicated that athletes' strength trained 2-3 times a week. Almost all coaches (94%) reported their rowers performed strength training, with 81% using Olympic lifting, and 91% employing a periodized training model. The clean (63%) and squat (27%) were rated the most important prescribed exercises. Approximately 50% of coaches used plyometrics such as depth jumps, box drills, and standing jumps. Ninety-four percent indicated they conducted physical testing on their rowers, typically assessing cardiovascular endurance (80%), muscular power (70%), muscular strength (70%), and anaerobic capacity (57%). This research represents the only published survey to date on the S&C practices in rowing within Great Britain
Neutron stars from young nearby associations the origin of RXJ1605.3+3249
Many neutron stars (NSs) and runaway stars apparently come from the same
regions on the sky. This suggests that they share the same birth places, namely
associations and clusters of young massive stars. To identify NS birth places,
we attempt to and NS-runaway pairs that could be former companions that were
disrupted in a supernova (SN). The remains of recent (<few Myr) nearby (< 150
pc) SNe should still be identifiable by observing the emission of rare
radioisotopes such as 26Al and 60Fe that can also be used as additional
indicators to confirm a possible SN event. We investigated the origin of the
isolated NS RXJ1605.3+3249 and found that it was probably born ~100 pc far from
Earth 0.45 Myr ago in the extended Corona-Australis or Octans associations, or
in Sco OB4 ~1 kpc 3.5 Myr ago. A SN in Octans is supported by the
identification of one to two possible former companions the runaway stars HIP
68228 and HIP 89394, as well as the appearance of a feature in the gamma ray
emission from 26Al decay at the predicted SN place. Both, the progenitor masses
estimated by comparison with theoretical 26Al yields as well as derived from
the life time of the progenitor star, are found to be ~11MSun.Comment: accepted for publication in PASA, special volume Astronomy with
Radioactivities; 10 pages, 4 figures, 5 table
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