9,245 research outputs found
Before and Beyond Divergence: A New Look at the Economic History of China and Europe [Book Review]
Before and Beyond Divergence is a model of collaboration and academic production: between two disciplines—economics and history and between two area specialists—an economic historian of Europe and a socioeconomic historian of China
Incorporating simulated spatial context information improves the effectiveness of contrastive learning models
Visual learning often occurs in a specific context, where an agent acquires
skills through exploration and tracking of its location in a consistent
environment. The historical spatial context of the agent provides a similarity
signal for self-supervised contrastive learning. We present a unique approach,
termed Environmental Spatial Similarity (ESS), that complements existing
contrastive learning methods. Using images from simulated, photorealistic
environments as an experimental setting, we demonstrate that ESS outperforms
traditional instance discrimination approaches. Moreover, sampling additional
data from the same environment substantially improves accuracy and provides new
augmentations. ESS allows remarkable proficiency in room classification and
spatial prediction tasks, especially in unfamiliar environments. This learning
paradigm has the potential to enable rapid visual learning in agents operating
in new environments with unique visual characteristics. Potentially
transformative applications span from robotics to space exploration. Our proof
of concept demonstrates improved efficiency over methods that rely on
extensive, disconnected datasets
What Explains Vietnam's Exceptional Performance in Education Relative to Other Countries? Analysis of the Young Lives Data from Ethiopia, Peru, India and Vietnam
Vietnam’s strong performance on the 2012 and 2015 PISA assessments has led to interest in what explains the strong academic performance of Vietnamese students. Analysis of the PISA data has not shed much light on this issue. This paper analyses a much richer data set, the Young Lives data for Ethiopia, India (Andhra Pradesh and Telangana), Peru and Vietnam, to investigate the reasons for the strong academic performance of 15-year-olds in Vietnam. Differences in observed child and household characteristics explain 37-39 percent of the gap between Vietnam, and Ethiopia, while observed school variables explain only about 3-4 additional percentage points (although an important variable, math teachers’ pedagogical skills, is not available for Ethiopia). Differences in observed child and household characteristics explain very little of the gaps between Vietnam and India and between Vietnam and Peru, yet one observed school variable has a large explanatory effect: primary school math teachers’ pedagogical skills. It explains about 10-12 percent of the gap between Vietnam and India, raising the overall explained portion to 14-21 percent of the gap. For Peru, it explains most (65-84 percent) of the gap
Bayesian inference on random simple graphs with power law degree distributions
We present a model for random simple graphs with power law (i.e., heavy-tailed) degree dis- tributions. To attain this behavior, the edge probabilities in the graph are constructed from Bertoin–Fujita–Roynette–Yor (BFRY) random variables, which have been recently utilized in Bayesian statistics for the construction of power law models in several applications. Our construction readily extends to capture the structure of latent factors, similarly to stochastic block- models, while maintaining its power law degree distribution. The BFRY random variables are well approximated by gamma random variables in a variational Bayesian inference routine, which we apply to several network datasets for which power law degree distributions are a natural assumption. By learning the parameters of the BFRY distribution via probabilistic inference, we are able to automatically select the appropriate power law behavior from the data. In order to further scale our inference procedure, we adopt stochastic gradient ascent routines where the gradients are computed on minibatches (i.e., sub- sets) of the edges in the graph.J. Lee and S. Choi were partly supported by an Institute for Information & Communications Technology Promotion (IITP) grant, funded by the Korean government (MSIP) (No.2014- 0-00147, Basic Software Research in Human-level Life- long Machine Learning (Machine Learning Center)) and Naver, Inc. C. Heaukulani undertook this work in part while a visiting researcher at the Hong Kong University of Science and Technology, who along with L. F. James was funded by grant rgc-hkust 601712 of the Hong Kong Special Administrative Region.
EPSRC Grant EP/N014162/1
ATI Grant EP/N510129/
A method for evaluating the murine pulmonary vasculature using micro-computed tomography
AbstractBackgroundSignificant mortality and morbidity are associated with alterations in the pulmonary vasculature. While techniques have been described for quantitative morphometry of whole-lung arterial trees in larger animals, no methods have been described in mice. We report a method for the quantitative assessment of murine pulmonary arterial vasculature using high-resolution computed tomography scanning.MethodsMice were harvested at 2 weeks, 4 weeks, and 3 months of age. The pulmonary artery vascular tree was pressure perfused to maximal dilation with a radio-opaque casting material with viscosity and pressure set to prevent capillary transit and venous filling. The lungs were fixed and scanned on a specimen computed tomography scanner at 8-μm resolution, and the vessels were segmented. Vessels were grouped into categories based on lumen diameter and branch generation.ResultsRobust high-resolution segmentation was achieved, permitting detailed quantitation of pulmonary vascular morphometrics. As expected, postnatal lung development was associated with progressive increase in small-vessel number and arterial branching complexity.ConclusionsThese methods for quantitative analysis of the pulmonary vasculature in postnatal and adult mice provide a useful tool for the evaluation of mouse models of disease that affect the pulmonary vasculature
Small-sized dichroic atomic vapor laser lock
Two, lightweight diode laser frequency stabilization systems designed for
experiments in the field are described. A significant reduction in size and
weight in both models supports the further miniaturization of measurement
devices in the field. Similar to a previous design, magnetic-field lines are
contained within a magnetic shield enclosing permanent magnets and a Rb cell,
so that these DAVLL systems may be used for magnetically sensitive instruments.
The Mini-DAVLL system (49 mm long) uses a vapor cell (20 mm long), and does not
require cell heaters. An even smaller Micro-DAVLL system (9mm long) uses a
micro-fabricated cell (3 mm square), and requires heaters. These new systems
show no degradation in performance with regard to previous designs, while
considerably reducing dimensions.Comment: 13 pages, 11 figures, published versio
The seasonality of infections in tropical Far North Queensland, Australia: A 21-year retrospective evaluation of the seasonal patterns of six endemic pathogens
An understanding of the seasonality of infections informs public health strategies and assists clinicians in their management of patients with undifferentiated illness. The seasonality of infections is driven by a variety of environmental and human factors; however, the role of individual climatic factors has garnered much attention. This study utilises Poisson regression models to assess the seasonality of six important infections in tropical Australia and their association with climatic factors and severe weather events over a 21-year period. Melioidosis and leptospirosis showed marked wet season predominance, while more cases of rickettsial disease and cryptococcosis were seen in cooler, drier months. Staphylococcus aureus infections were not seasonal, while influenza demonstrated inter-seasonality. The climate did not significantly change during the 21 years of the study period, but the incidence of melioidosis and rickettsial disease increased considerably, highlighting the primacy of other factors-including societal inequality, and the impact of urban expansion-in the incidence of these infections. While anthropogenic climate change poses a threat to the region-and may influence the burden of these infections in the future-this study highlights the fact that, even for seasonal diseases, other factors presently have a greater effect on disease incidence. Public health strategies must also target these broader drivers of infection if they are to be effective
Measuring health-related quality of life outcomes in bladder cancer patients using the Bladder Cancer Index (BCI)
BACKGROUND. Health-related quality of life (HRQOL) has not been adequately measured in bladder cancer. A recently developed reliable and disease-specific quality of life instrument (Bladder Cancer Index, BCI) was used to measure urinary, sexual, and bowel function and bother domains in patients with bladder cancer managed with several different interventions, including cystectomy and endoscopic-based procedures. METHODS. Patients with bladder cancer were identified from a prospective bladder cancer outcomes database and contacted as part of an Institutional Review Board-approved study to assess treatment impact on HRQOL. HRQOL was measured using the BCI across stratified treatment groups. Bivariate and multivariable analyses adjusted for age, gender, income, education, relationship status, and follow-up time were performed to compare urinary, bowel, and sexual domains between treatment groups. RESULTS. In all, 315 bladder cancer patients treated at the University of Michigan completed the BCI in 2004. Significant differences were seen in mean BCI function and bother scores between cystectomy and native bladder treatment groups. In addition, urinary function scores were significantly lower among cystectomy patients treated with continent neobladder compared with those treated with ileal conduit (all pairwise P < .05). CONCLUSIONS. The BCI is responsive to functional and bother differences in patients with bladder cancer treated with different surgical approaches. Significant differences between therapy groups in each of the urinary, bowel, and sexual domains exist. Among patients treated with orthotopic continent urinary diversion, functional impairments related to urinary incontinence and lack of urinary control account for the low observed urinary function scores. Cancer 2007. © 2007 American Cancer Society.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55989/1/22556_ftp.pd
Pion Breather States in QCD
We describe a class of pionic breather solutions (PBS) which appear in the
chiral lagrangian description of low-energy QCD. These configurations are
long-lived, with lifetimes greater than fm/c, and could arise as
remnants of disoriented chiral condensate (DCC) formation at RHIC. We show that
the chiral lagrangian equations of motion for a uniformly isospin-polarized
domain reduce to those of the sine-gordon model. Consequently, our solutions
are directly related to the breather solutions of sine-gordon theory in 3+1
dimensions. We investigate the possibility of PBS formation from multiple
domains of DCC, and show that the probability of formation is non-negligible.Comment: 9 pages, 4 figure
Can codimension-two branes solve the cosmological constant problem?
It has been suggested that codimension-two braneworlds might naturally
explain the vanishing of the 4D effective cosmological constant, due to the
automatic relation between the deficit angle and the brane tension. To
investigate whether this cancellation happens dynamically, and within the
context of a realistic cosmology, we study a codimension-two braneworld with
spherical extra dimensions compactified by magnetic flux. Assuming Einstein
gravity, we show that when the brane contains matter with an arbitrary equation
of state, the 4D metric components are not regular at the brane, unless the
brane has nonzero thickness. We construct explicit 6D solutions with thick
branes, treating the brane matter as a perturbation, and find that the universe
expands consistently with standard Friedmann-Robertson-Walker (FRW) cosmology.
The relation between the brane tension and the bulk deficit angle becomes
for a general equation of state. However, this
relation does not imply a self-tuning of the effective 4D cosmological constant
to zero; perturbations of the brane tension in a static solution lead to
deSitter or anti-deSitter braneworlds. Our results thus confirm other recent
work showing that codimension-two braneworlds in nonsupersymmetric Einstein
gravity do not lead to a dynamical relaxation of the cosmological constant, but
they leave open the possibility that supersymmetric versions can be compatible
with self-tuning.Comment: Revtex4, 17 pages, references added, typos corrected, minor points
clarified. Matches published versio
- …