4,558 research outputs found
Detection of artificially injected signals in the cosmic microwave background
Honors (Bachelor's)PhysicsUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/91786/1/sophz.pd
Effective Strategies for Integrating STEM Education into Chinese Language Classroom
1. What is STEM?
-How can it be integrated into the current language curriculum?
2. Why STEM?
-Trend of offering the Mandarin course at K-12 schools
3. Chinese Curriculum & STEM-focused topics
-The STEM-focused topics incorporated at IMSA
4. Teaching strategies
-Lesson design, use of authentic materials, activitie
Fitness of antimicrobial-resistant Campylobacter and Salmonella
Campylobacter and Salmonella are the most commonly reported bacterial causes of human foodborne infections, and increasing proportions of these pathogens become resistant to medically important antimicrobial agents, imposing a burden on public health. Acquisition of resistance to antibiotics affects the adaptation and evolution of Salmonella and Campylobacter in various environments. Many resistance-conferring mutations entail a biological fitness cost, while others (e.g. fluoroquinolone resistance in Campylobacter) have no cost or even enhanced fitness. In Salmonella, the fitness disadvantage due to antimicrobial resistance can be restored by acquired compensatory mutations, which occur both in vitro and in vivo. The compensated or even enhanced fitness associated with antibiotic resistance may facilitate the spread and persistence of antimicrobial-resistant Salmonella and Campylobacter in the absence of selection pressure, creating a significant barrier for controlling antibiotic-resistant foodborne pathogens
Upper and Lower Bounds on the Smoothed Complexity of the Simplex Method
The simplex method for linear programming is known to be highly efficient in
practice, and understanding its performance from a theoretical perspective is
an active research topic. The framework of smoothed analysis, first introduced
by Spielman and Teng (JACM '04) for this purpose, defines the smoothed
complexity of solving a linear program with variables and constraints
as the expected running time when Gaussian noise of variance is
added to the LP data. We prove that the smoothed complexity of the simplex
method is , improving the dependence on
compared to the previous bound of .
We accomplish this through a new analysis of the \emph{shadow bound}, key to
earlier analyses as well. Illustrating the power of our new method, we use our
method to prove a nearly tight upper bound on the smoothed complexity of
two-dimensional polygons.
We also establish the first non-trivial lower bound on the smoothed
complexity of the simplex method, proving that the \emph{shadow vertex simplex
method} requires at least pivot steps with high probability. A key
part of our analysis is a new variation on the extended formulation for the
regular -gon. We end with a numerical experiment that suggests this
analysis could be further improved.Comment: 41 pages, 5 figure
Rorc restrains the potency of ST2+ regulatory T cells in ameliorating intestinal graft-versus-host disease
Soluble stimulation-2 (ST2) is increased during graft-versus-host disease (GVHD), while Tregs that express ST2 prevent GVHD through unknown mechanisms. Transplantation of Foxp3- T cells and Tregs that were collected and sorted from different Foxp3 reporter mice indicated that in mice that developed GVHD, ST2+ Tregs were thymus derived and predominantly localized to the intestine. ST2-/- Treg transplantation was associated with reduced total intestinal Treg frequency and activation. ST2-/- versus WT intestinal Treg transcriptomes showed decreased Treg functional markers and, reciprocally, increased Rorc expression. Rorc-/- T cells transplantation enhanced the frequency and function of intestinal ST2+ Tregs and reduced GVHD through decreased gut-infiltrating soluble ST2-producing type 1 and increased IL-4/IL-10-producing type 2 T cells. Cotransfer of ST2+ Tregs sorted from Rorc-/- mice with WT CD25-depleted T cells decreased GVHD severity and mortality, increased intestinal ST2+KLRG1+ Tregs, and decreased type 1 T cells after transplantation, indicating an intrinsic mechanism. Ex vivo IL-33-stimulated Tregs (TregIL-33) expressed higher amphiregulin and displayed better immunosuppression, and adoptive transfer prevented GVHD better than control Tregs or TregIL-33 cultured with IL-23/IL-17. Amphiregulin blockade by neutralizing antibody in vivo abolished the protective effect of TregIL-33. Our data show that inverse expression of ST2 and RORÎłt in intestinal Tregs determines GVHD and that TregIL-33 has potential as a cellular therapy avenue for preventing GVHD
Sylow -groups of polynomial permutations on the integers mod
We describe the Sylow -groups of the group of polynomial permutations of
the integers mod
Training biases in machine learning for the analytic continuation of quantum many-body Green's functions
We address the problem of analytic continuation of imaginary-frequency
Green's functions, which is crucial in many-body physics, using machine
learning based on a multi-level residual neural network. We specifically
address potential biases that can be introduced due to the use of artificially
created spectral functions that are employed to train the neural network. We
also implement an uncertainty estimation of the predicted spectral function,
based on Monte Carlo dropout, which allows to identify frequency regions where
the prediction might not be accurate, and we study the effect of noise, in
particular also for situations where the noise level during training is
different from that in the actual data. Our analysis demonstrates that this
method can indeed achieve a high quality of prediction, comparable or better
than the widely used maximum entropy method, but that further improvement is
currently limited by the lack of true data that can be used for training. We
also benchmark our approach by applying it to the case of SrVO, where an
accurate spectral function has been obtained from dynamical mean-field theory
using a solver that works directly on the real frequency axis
Setting up local travel plan groups : the future of workplace travel planning in urban conurbations? Examples from London, UK.
Any group of organisations that comes together to share resources and ideas for developing
and implementing a travel plan (site based Transportation Demand Management plan, known
as a Travel Plan in the UK) in their local area could be described as a local travel plan group.
Whilst the concept is not new for workplace travel planning in North America, recently
several new variants have been established in the UK.
This paper reviews and sets out a typology of local travel plan groups, including
development zones, area based groups, Transportation Management Associations and
Business Improvement Districts. It then highlights the case of London, where, perhaps
uniquely, at least one example of each type of group is present. One new example is then
examined in more detail to illustrate some of the challenges in setting up a local travel plan
group and the way in which they may develop in the future to providing a framework for
involving businesses in local transport improvement decisions. Finally, the main
characteristics of the London groups and how they differ from their North American
predecessors are briefly explored
Les facteurs institutionnels associĂ©s aux infections et Ă la mortalitĂ© COVID-19 en centre dâhĂ©bergement pendant la premiĂšre vague : une analyse de 17 CHSLD Ă MontrĂ©al
Contexte : Partout dans le monde, la population ĂągĂ©e en hĂ©bergement a Ă©tĂ© la plus lourdement affectĂ©e par la pandĂ©mie de COVID-19, du point de vue des infections et des dĂ©cĂšs. Or, ces mĂȘmes personnes ont Ă©tĂ© exclues dâune grande partie de la littĂ©rature scientifique. Ce mĂ©moire dĂ©crit lâĂ©volution des Ă©closions dans 17 CHSLD publics de MontrĂ©al, dont certains ont Ă©tĂ© fortement atteints alors que dâautres ont Ă©tĂ© Ă©pargnĂ©s pendant la premiĂšre vague (23 fĂ©vrier au 11 juillet 2020), en cherchant Ă Ă©lucider les facteurs associĂ©s Ă lâincidence et Ă la lĂ©talitĂ© de la COVID-19.
MĂ©thodes : Des donnĂ©es institutionnelles ont Ă©tĂ© recueillies sur les 17 CHSLD du CIUSSS Centre-Sud-de-l'Ăle-de-MontrĂ©al et des donnĂ©es individuelles ont Ă©tĂ© obtenues grĂące Ă une rĂ©vision des 1197 dossiers de patients atteints de la COVID-19 en premiĂšre vague. Dans lâanalyse ARIMA, des sĂ©ries chronologiques ont Ă©tĂ© construites pour les cas incidents bruts chez les rĂ©sidents en CHSLD et dans la ville de MontrĂ©al, afin dâĂ©valuer lâimpact de deux interventions, soit le port gĂ©nĂ©ralisĂ© du masque de procĂ©dure et le dĂ©pistage Ă©largi des rĂ©sidents et des employĂ©s. Dans lâanalyse des infections par CHSLD, des modĂšles de rĂ©gression de type binomial nĂ©gatif ont Ă©tĂ© construits pour estimer lâeffet des facteurs de risque institutionnels sur lâincidence de la COVID-19 chez les rĂ©sidents. Dans lâanalyse de surmortalitĂ©, les excĂšs de dĂ©cĂšs durant la pĂ©riode de fĂ©vrier Ă juillet ont Ă©tĂ© Ă©valuĂ©s avec des tests t et des ratios de taux entre lâannĂ©e 2020 et la moyenne des quatre annĂ©es prĂ©cĂ©dentes (2016-2019). Enfin, pour lâanalyse de mortalitĂ© dans la cohorte rĂ©trospective de rĂ©sidents atteints de la COVID-19, des modĂšles de rĂ©gression logistique Ă effets mixtes ont Ă©tĂ© utilisĂ©s pour Ă©valuer les facteurs institutionnels et les traitements associĂ©s Ă la mortalitĂ© dans les 30 jours suivant un diagnostic de COVID-19, en contrĂŽlant pour les facteurs de risque individuels.
RĂ©sultats : Dans lâanalyse de sĂ©rie chronologique ARIMA, chaque augmentation dâun cas incident quotidien par 100 000 Ă MontrĂ©al Ă©tait associĂ©e avec une augmentation de 0,051 (IC95% 0,044 Ă 0,058) fois lâincidence quotidienne en CHSLD la semaine suivante, chez les rĂ©sidents Ă risque. De plus, en contrĂŽlant pour la transmission communautaire, chaque palier dâintensification du dĂ©pistage Ă©tait associĂ© Ă une diminution de lâincidence de 11,8 fois (IC95% -15,1 Ă -8,5) dans les deux semaines suivantes, chez les rĂ©sidents Ă risque.
Dans le modĂšle explicatif des infections au niveau des CHSLD, la pĂ©nurie sĂ©vĂšre dâinfirmiĂšres auxiliaires (IRR 3,2; IC95% 1,4 Ă 7,2), la mauvaise performance aux audits ministĂ©riels (IRR 3,0; IC95% 1,1 Ă 7,8) et un score moyen dâautonomie plus faible (IRR 2,1; IC95% 1,4 Ă 3,1) Ă©taient associĂ©s au taux dâincidence par centre. En revanche, la prĂ©sence de zone chaude dĂ©diĂ©e aux patients COVID-19 (IRR; 0,56 IC95% 0,34 Ă 0,92) Ă©tait protectrice.
Pour lâensemble des 17 CHSLD avec 2670 lits, lâexcĂšs de dĂ©cĂšs de fĂ©vrier Ă juillet 2020 Ă©tait de 428 (IC95% 409 Ă 447). ComparĂ© aux quatre annĂ©es prĂ©cĂ©dentes, il y a eu plus que le double (IRR 2,3; IC95% 2,1 Ă 2,5) de dĂ©cĂšs en 2020 pendant la pĂ©riode de la premiĂšre vague. Pour 12 CHSLD qui ont vĂ©cu des Ă©closions importantes, les excĂšs de dĂ©cĂšs en 2020 variaient de 5,2 Ă 41,9 dĂ©cĂšs par 100 lits, avec une surmortalitĂ© par rapport aux annĂ©es prĂ©cĂ©dentes allant de 1,9 Ă 3,8.
Selon lâanalyse de mortalitĂ© dans la cohorte rĂ©trospective, les facteurs individuels associĂ©s Ă la mortalitĂ© dans les 30 jours suivant le diagnostic de COVID-19 Ă©taient lâĂąge (OR 1,58; IC95% 1,35 Ă 1,85 par tranche additionnelle de 10 ans), le sexe masculin (OR 2,37; IC95% 1,70 Ă 3,32), la perte dâautonomie (OR 1,12; IC95% 1,05 Ă 1,20 pour chaque augmentation dâun point Ă lâIso-SMAF), le niveau dâintervention mĂ©dicale C (OR 3,43; IC95% 1,57 Ă 7,51) et D (OR 3,61; IC95% 1,47 Ă 8,89) comparĂ© au niveau A, ainsi que les diagnostics de trouble neurocognitif (OR 1,54; IC95% 1,04 Ă 2,29) et dâinsuffisance cardiaque (OR 2,36; IC95% 1,45 Ă 3,85). Le traitement avec une thromboprophylaxie (OR 0,42; IC95% 0,29 Ă 0,63) et lâinfection tardive aprĂšs le 20 avril 2020 (OR 0,46; IC95% 0,33 Ă 0,65) Ă©taient associĂ©s Ă la survie Ă 30 jours. Pour les facteurs institutionnels, la pĂ©nurie sĂ©vĂšre de 25% ou plus dâinfirmiĂšres auxiliaires (OR 1,91; IC95% 1,14 Ă 3,21 par rapport Ă une pĂ©nurie lĂ©gĂšre < 15%) et la taille du centre (OR 1,77; IC95% 1,17 Ă 2,68 pour chaque 100 lits additionnels) Ă©taient associĂ©s au dĂ©cĂšs dans les 30 jours.
Conclusion : Ce mĂ©moire a relevĂ© plusieurs facteurs de risque modifiables au niveau institutionnel associĂ©s aux infections et aux dĂ©cĂšs COVID-19, dont le dĂ©pistage, lâadhĂ©rence aux directives ministĂ©rielles de prĂ©vention et contrĂŽle des infections, la pĂ©nurie dâinfirmiĂšres auxiliaires et le nombre de lits par centre. Ces enjeux cruciaux devront ĂȘtre au cĆur des futures orientations et politiques touchant les centres dâhĂ©bergement, pour cette pandĂ©mie et au-delĂ .Background: In the midst of the COVID-19 pandemic, the population of long-term care residents has been the hardest hit by infections and deaths all around the world. Yet, these same individuals have been excluded from vast segments of the scientific literature. This thesis describes the evolution of outbreaks in 17 public long-term care facilities (âCHSLDâ) in Montreal, some of which were severely affected and others were relatively spared during the first wave (February 23 to July 12, 2020), in search of risk factors associated with COVID-19 cases and deaths.
Methods: Institutional-level data on the 17 CHSLDs were collected from relevant administrative departments within the establishment (CIUSSS Centre-Sud-de-l'Ăle-de-MontrĂ©al), and individual-level data was obtained from the chart reviews of 1,197 first wave COVID-19 patients. For the ARIMA analysis, time series were built using the crude incidence rates among CHSLD residents and in the city of Montreal, in order to assess the impact of two interventions â introduction of the mask-wearing policy and generalized testing among residents and staff. For the analysis of facility-level infection rates, negative binomial regression models were built to estimate the effects of several institutional risk factors on incident cases. As for the excess mortality analysis, excess death and relative mortality were estimated using one-sample t-tests and rate ratio tests to compare 2020 deaths with average deaths in the previous four years (2016-2019), for the period of February to July. Lastly, for the survival analysis of the retrospective cohort, mixed-effects logistic regression models were used to identify institutional factors and treatments associated with 30-day mortality after a COVID-19 diagnosis, while controlling for individual risk factors.
Results: In the ARIMA time series analysis, each additional case per 100,000 per day in Montreal was associated with a 0.051 (95%CI 0.044 to 0.058) increase in CHSLD daily incidence a week later, among at-risk residents. In addition, while controlling for community transmission, increased testing intensity was associated with a 11.8 (95%CI -15.1 to -8.5) decrease in CHSLD daily incidence two weeks later, among at-risk residents.
In the negative binomial regression model for facility-level COVID-19 infections, poor performance on ministry audits (IRR 3.0 95%CI 1.1 to 7.8), severe shortage of auxiliary nurses (IRR 3.2 95%CI 1.4 to 7.2) and lower average autonomy scores (IRR 2.1 95%CI 1.4 to 3.1) were associated with incident cases, while the presence of a COVID-19 unit or âred zoneâ (IRR 0.56 95%CI 0.34 to 0.92) was inversely associated with infections.
For the 17 CHSLDs, excess deaths from February to July 2020 was 428 (95%CI 409 to 447). Compared to the same period in the previous four years, 2020 mortality during the first wave was 2.3 (IRR 95%CI 2.1 to 2.5) times higher. For a subset of 12 facilities that experienced substantial outbreaks, excess deaths in 2020 varied from 5.2 to 41.9 deaths per 100 beds, with significant excess mortality between 1.9 and 3.8, relative to previous years.
According to the mortality analysis by mixed-effects logistic regression, individual risk factors associated with 30-day mortality after a COVID-19 diagnosis were age (OR 1.58 95%CI 1.35 to 1.85 per additional 10 years), male sex (OR 2.37 95%CI 1.70 to 3.32), loss of autonomy (OR 1.12 95%CI 1.05 to 1.20 per unit increase of Iso-SMAF profile), C-level (OR 3.43 95%CI 1.57 to 7.51) or D-level (OR 3.61 95%CI 1.47 to 8.89) medical intervention compared to A-level, as well as being diagnosed with a neurocognitive disorder (OR 1.54 95%CI 1.04 to 2.29) or congestive heart failure (OR 2.36 95%CI 1.45 to 3.85). Treatment with thromboprophylaxis (OR 0.42 95%CI 0.29 to 0.63) and diagnosis after April 20, 2020 (OR 0.46 95%CI 0.33 to 0.65) were associated with 30-day survival. As for institutional risk factors, severe shortage of auxiliary nurses (OR 1.91 95%CI 1.14 to 3.21) and facility size (OR 1.77 95%CI 1.17 to 2.68 per 100 beds) increased the odds of dying within 30 days.
Conclusion: This study identified several modifiable risk factors at the institutional level associated with COVID-19 infections and deaths, including testing strategies, adherence to ministry directives for infection prevention, auxiliary nurse shortages, and number of beds per facility. Future policies and regulations targeting long-term care facilities will need to tackle these critical issues, for this pandemic and beyond
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