7,831 research outputs found
Fundraising and vote distribution: a non-equilibrium statistical approach
The number of votes correlates strongly with the money spent in a campaign,
but the relation between the two is not straightforward. Among other factors,
the output of a ballot depends on the number of candidates, voters, and
available resources. Here, we develop a conceptual framework based on Shannon
entropy maximization and Superstatistics to establish a relation between the
distributions of money spent by candidates and their votes. By establishing
such a relation, we provide a tool to predict the outcome of a ballot and to
alert for possible misconduct either in the report of fundraising and spending
of campaigns or on vote counting. As an example, we consider real data from a
proportional election with candidates, where a detailed data
verification is virtually impossible, and show that the number of potential
misconducting candidates to audit can be reduced to only nine
BBQ Grill Temperature Uniformity Study
Bull Outdoor Products, Incorporated, a barbeque grill and outdoor kitchen manufacturer, sponsored this project with the intent of improving the temperature uniformity across the surface of their barbecue grills. For this project, the Cal Poly team of mechanical engineering students, Monty Dodge Jr. and Samuel Melo, used the Brahma grill head model with setups for both natural gas and propane. In order to determine exactly what the uniformity across the grill surface was, the student team designed a testing apparatus which would measure a grid of temperature locations one inch apart spanning an area 16 by 36 inches. Developing a testing method which produced accurate results was done over five separate tests, at which point the team began testing various geometrical configurations of flame guards (flame tamers) to determine how these geometries affected the overall temperature uniformity. Across all of the tests, the results clearly showed that temperature in the back of the grill was consistently higher than the front. It was also found that approximately half of the propane grill, on the left side, was significantly lower temperature than the right. Upon further investigation, and bench testing a propane manifold for pressure at each valve, it was determined the cause of the discrepancy in temperature from left to right was the result of a pressure drop in the manifold. Recommendations were then made to Bull Outdoor Products with regard to how this might be improved. The student team did, in the end, design a set of louvers which would direct heat flow from the back to the front of grill. These new louvers did improve the temperature distribution from front to back, however, the most valuable deliverable was the actual design of the test apparatus, the test method, and method of data analysis used
Portinari: A Data Exploration Tool to Personalize Cervical Cancer Screening
Socio-technical systems play an important role in public health screening
programs to prevent cancer. Cervical cancer incidence has significantly
decreased in countries that developed systems for organized screening engaging
medical practitioners, laboratories and patients. The system automatically
identifies individuals at risk of developing the disease and invites them for a
screening exam or a follow-up exam conducted by medical professionals. A triage
algorithm in the system aims to reduce unnecessary screening exams for
individuals at low-risk while detecting and treating individuals at high-risk.
Despite the general success of screening, the triage algorithm is a
one-size-fits all approach that is not personalized to a patient. This can
easily be observed in historical data from screening exams. Often patients rely
on personal factors to determine that they are either at high risk or not at
risk at all and take action at their own discretion. Can exploring patient
trajectories help hypothesize personal factors leading to their decisions? We
present Portinari, a data exploration tool to query and visualize future
trajectories of patients who have undergone a specific sequence of screening
exams. The web-based tool contains (a) a visual query interface (b) a backend
graph database of events in patients' lives (c) trajectory visualization using
sankey diagrams. We use Portinari to explore diverse trajectories of patients
following the Norwegian triage algorithm. The trajectories demonstrated
variable degrees of adherence to the triage algorithm and allowed
epidemiologists to hypothesize about the possible causes.Comment: Conference paper published at ICSE 2017 Buenos Aires, at the Software
Engineering in Society Track. 10 pages, 5 figure
On Dirac-like Monopoles in a Lorentz- and CPT-violating Electrodynamics
We study magnetic monopoles in a Lorentz- and CPT-odd electrodynamical
framework in (3+1) dimensions. This is the standard Maxwell model extended by
means of a Chern-Simons-like term, (
constant), which respects gauge invariance but violates both Lorentz and CPT
symmetries (as a consequence, duality is also lost). Our main interest concerns
the analysis of the model in the presence of Dirac monopoles, so that the
Bianchi identity no longer holds, which naively yields the non-conservation of
electric charge. Since gauge symmetry is respected, the issue of charge
conservation is more involved. Actually, the inconsistency may be circumvented,
if we assume that the appearance of a monopole induces an extra electric
current. The reduction of the model to (2+1) dimensions in the presence of both
the magnetic sources and Lorentz-violating terms is presented. There, a
quantization condition involving the scalar remnant of , say, the mass
parameter, is obtained. We also point out that the breaking of duality may be
associated with an asymmetry between electric and magnetic sources in this
background, so that the electromagnetic force experienced by a magnetic pole is
supplemented by an extra term proportional to , whenever compared to the
one acting on an electric charge.Comment: 10 pages, no figures, typed in te
Human Mobility in Large Cities as a Proxy for Crime
We investigate at the subscale of the neighborhoods of a highly populated
city the incidence of property crimes in terms of both the resident and the
floating population. Our results show that a relevant allometric relation could
only be observed between property crimes and floating population. More
precisely, the evidence of a superlinear behavior indicates that a
disproportional number of property crimes occurs in regions where an increased
flow of people takes place in the city. For comparison, we also found that the
number of crimes of peace disturbance only correlates well, and in a
superlinear fashion too, with the resident population. Our study raises the
interesting possibility that the superlinearity observed in previous studies
[Bettencourt et al., Proc. Natl. Acad. Sci. USA 104, 7301 (2007) and Melo et
al., Sci. Rep. 4, 6239 (2014)] for homicides versus population at the city
scale could have its origin in the fact that the floating population, and not
the resident one, should be taken as the relevant variable determining the
intrinsic microdynamical behavior of the system.Comment: 17 pages, 8 Figure
Unsupervised Learning Applied to the Stratification of Preterm Birth Risk in Brazil with Socioeconomic Data
The authors wish to acknowledge the financial support of the CoordenacAo de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) for their financial support.Preterm birth (PTB) is a phenomenon that brings risks and challenges for the survival of
the newborn child. Despite many advances in research, not all the causes of PTB are already clear. It
is understood that PTB risk is multi-factorial and can also be associated with socioeconomic factors.
Thereby, this article seeks to use unsupervised learning techniques to stratify PTB risk in Brazil
using only socioeconomic data. Through the use of datasets made publicly available by the Federal
Government of Brazil, a new dataset was generated with municipality-level socioeconomic data and
a PTB occurrence rate. This dataset was processed using various unsupervised learning techniques,
such as k-means, principal component analysis (PCA), and density-based spatial clustering of applications
with noise (DBSCAN). After validation, four clusters with high levels of PTB occurrence
were discovered, as well as three with low levels. The clusters with high PTB were comprised mostly
of municipalities with lower levels of education, worse quality of public services—such as basic
sanitation and garbage collection—and a less white population. The regional distribution of the
clusters was also observed, with clusters of high PTB located mostly in the North and Northeast
regions of Brazil. The results indicate a positive influence of the quality of life and the offer of public
services on the reduction in PTB risk.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES
On the nature of Lithium-rich giant stars: constraints from Beryllium abundances
We have derived beryllium abundances for 7 Li-rich giant (A(Li) > 1.5) stars
and 10 other Li-normal giants, with the aim of investigating the origin of the
Lithium in the Li-rich giants. In particular, we test the predictions of the
engulfment scenario proposed by Siess & Livio (1999), where the engulfment of a
brown dwarf or one or more giant planets would lead to a simultaneous
enrichment of 7Li and 9Be. We show that regardless their nature, none of the
stars studied in this paper were found to have detectable beryllium. Using
simple dilution arguments we show that the engulfment of an external object as
the sole source of Li enrichment is ruled out by the Li and Be abundance data.
The present results favor the idea that Li has been produced in the interior of
the stars by a Cameron-Fowler process and brought up to the surface by an extra
mixing mechanism.Comment: Accepted in A&
Exponential Growth of Particle Number far from the Parametric Resonance Regime
Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields and the inflaton , or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian . However, for the interaction Lagrangian , our formalism shows that in the large coupling limit there can only be exponential particle production when crosses 0.Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields and the inflaton , or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian . However, for the interaction Lagrangian , our formalism shows that in the large coupling limit there can only be exponential particle production when crosses 0.Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields and the inflaton , or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian . However, for the interaction Lagrangian , our formalism shows that in the large coupling limit there can only be exponential particle production when crosses 0.Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields and the inflaton , or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian . However, for the interaction Lagrangian , our formalism shows that in the large coupling limit there can only be exponential particle production when crosses 0
- …