54,289 research outputs found
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Street Egohood: An Alternative Perspective of Measuring Neighborhood and Spatial Patterns of Crime
Objectives: The current study proposes an approach that accounts for the importance of streets while at the same time accounting for the overlapping spatial nature of social and physical environments captured by the egohood approach. Our approach utilizes overlapping clusters of streets based on the street network distance, which we term street egohoods. Methods: We used the street segment as a base unit and employed two strategies in clustering the street segments: (1) based on the First Order Queen Contiguity; and (2) based on the street network distance considering physical barriers. We utilized our approaches for measuring ecological factors and estimated crime rates in the Los Angeles metropolitan area. Results: We found that whereas certain socio-demographics, land use, and business employee measures show stronger relationships with crime when measured at the smaller street based unit, a number of them actually exhibited stronger relationships when measured using our larger street egohoods. We compared the results for our three-sized street egohoods to street segments and two sizes of block egohoods proposed by Hipp and Boessen (Criminology 51(2):287–327, 2013) and found that two egohood strategies essentially are not different at the quarter mile egohood level but this similarity appears lower when looking at the half mile egohood level. Also, the street egohood models are a better fit for predicting violent and property crime compared to the block egohood models. Conclusions: A primary contribution of the current study is to develop and propose a new perspective of measuring neighborhood based on urban streets. We empirically demonstrated that whereas certain socio-demographic measures show the strongest relationship with crime when measured at the micro geographic unit of street segments, a number of them actually exhibited the strongest relationship when measured using our larger street egohoods. We hope future research can use egohoods to expand understanding of neighborhoods and crime
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Micro-Scale, Meso-Scale, Macro-Scale, and Temporal Scale: Comparing the Relative Importance for Robbery Risk in New York City
We compare the relative importance of four dimensions for explaining the micro location of robberies: 1) the micro spatial scale of street segments; 2) the meso spatial scale surrounding the street segment; 3) the temporal pattern, and 4) the macro-scale of the surrounding 2.5 miles. This study uses crime, business, and land use data from New York City and aggregates it to street segments and hours of the day. Although the measures capturing the micro-scale of the street segment explained the largest amount of unique variance, the measures capturing temporal scale across hours of the day (and weekdays) explained the next largest amount of unique variance. The measures of the characteristics in the 2.5 miles macro scale explained the next largest amount of unique variance, and combined with the measures at the meso-scale explained nearly as much of the variance as the street segment measures
THE EFFECT OF NEW FOOD LABELING ON NUTRIENT INTAKES: AN ENDOGENOUS SWITCHING REGRESSION ANALYSIS
This paper examines the effect of the new labeling regulations on nutrient intakes using an endogenous switching regression model. Using the 1994 - 96 CSFII/DHKS, we evaluate the impact of food label use on intakes of selected nutrients.Food Consumption/Nutrition/Food Safety,
HEALTH KNOWLEDGE AND CONSUMER USE OF NUTRITIONAL LABELS: THE ISSUE REVISITED
The role of health knowledge in consumer use of nutritional labels on food packages is explored using data from the 1995 Diet and Health Knowledge Survey. Two types of label use models, a binary choice label use model and a level of label use model, are employed with particular attention given to the endogeneity of health knowledge. The binary choice model is concerned with factors affecting the probability of label use. The level of label use model deals with factors affecting the number of food products in which label use occurred. The results show that health knowledge has a significant role in increasing label use.Food Consumption/Nutrition/Food Safety,
THE EFFECT OF FOOD LABEL USE ON NUTRIENT INTAKES: AN ENDOGENOUS SWITCHING REGRESSION ANALYSIS
This study examines the impact of consumers'Â’ use of food labels on selected nutrient intakes of Americans. Endogenous switching regression techniques are employed to control for heterogeneity in the label use decision. When the nutrient intakes of label users and the expected nutrient intakes of label users in the absence of labels are compared, food label use decreases individuals'Â’ average daily intakes of calories from total fat and saturated fat, cholesterol, and sodium by 6.90%, 2.10%, 67.60 milligrams, and 29.58 milligrams, respectively. In addition, consumer nutrition label use increases average daily fiber intake by 7.51 grains.Food Consumption/Nutrition/Food Safety,
Do Small-mass Neutrinos participate in Gauge Transformations?
Neutrino oscillation experiments presently suggest that neutrinos have a
small but finite mass. If neutrinos are to have mass, there should be a Lorentz
frame in which they can be brought to rest. This paper discusses how Wigner's
little groups can be used to distinguish between massive and massless
particles. We derive a representation of the SL(2,c) group which separates out
the two sets of spinors contained therein. One set is gauge dependent. The
other set is gauge-invariant and represents polarized neutrinos. We show that a
similar calculation can be done for the Dirac equation. In the
large-momentum/zero-mass limit, the Dirac spinors can be separated into large
and small components. The large components are gauge invariant, while the small
components are not. These small components represent spin-
non-zero mass particles. If we renormalize the large components, these gauge
invariant spinors again represent the polarization of neutrinos. Massive
neutrinos cannot be invariant under gauge transformations.Comment: 15 page
A latent ability to persist: differentiation in Toxoplasma gondii
A critical factor in the transmission and pathogenesis of Toxoplasma gondii is the ability to convert from an acute disease-causing, proliferative stage (tachyzoite), to a chronic, dormant stage (bradyzoite). The conversion of the tachyzoite-containing parasitophorous vacuole membrane into the less permeable bradyzoite cyst wall allows the parasite to persist for years within the host to maximize transmissibility to both primary (felids) and secondary (virtually all other warm-blooded vertebrates) hosts. This review presents our current understanding of the latent stage, including the factors that are important in bradyzoite induction and maintenance. Also discussed are the recent studies that have begun to unravel the mechanisms behind stage switching
Strength Properties of Preceramic Brazed Joints of a Gold-Palladium Alloy with a Microwave-assisted Oven and Gas/Oxygen Torch Technique
Statement of problem The effect of microwave brazing on the strength properties of dental casting alloys is not yet known. Purpose The purpose of this study was to compare the strength properties of preceramic brazed joints obtained by using a microwave oven and a conventional torch flame for a high noble alloy (Au-Pd). Material and methods A total of 18 tensile bars made of an Au-Pd ceramic alloy were fabricated. Six specimens were cut and joined with a high-fusing preceramic solder in a specially designed microwave oven, and 6 specimens were joined with a conventional natural gas/oxygen torch. The remaining 6 uncut specimens were tested as a control. All the specimens were subjected to testing with a universal testing machine. A 1-way ANOVA was performed for each strength property tested. Results
The tensile strength of the uncut group was the highest (745 ±19 MPa), followed by the microwave group (420 ±68 MPa) and the conventional torch group (348 ±103 MPa) (P Conclusions The microwave heating preceramic solder method demonstrated the excellent tensile strength of an Au-Pd alloy and may be an alternative way of joining alloys when a torch flame is contraindicated
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