380 research outputs found
Do student loans improve accessibility to higher education and student performance? An impact study of the SOFES program in Mexico
Financial aid to students in tertiary education can contribute to human capital accumulation through two channels: increased enrolment and improved student performance. We analyse the quantitative importance of both channels in the context of a student loan program (SOFES) implemented at private universities in Mexico. With regard to the first channel, results from the Mexican household survey indicate that financial support has a strongly positive effect on university enrolment. Two data sources are used to investigate the second channel, student performance. Administrative data provided by SOFES are analysed using a Regression-Discontinuity design, and survey data enable us to perform a similar analysis using a different control group. The empirical results suggest that SOFES recipients (i) show better academic performance, and (ii) tend to have more part-time jobs than students without a credit from SOFES.
Can student loans improve accessibility to higher education and student performance? An impact study of the case of SOFES, Mexico
Financial aid to students in tertiary education can contribute to human capital accumulation through two channels: increased enrollment and improved student performance. We analyze the quantitative importance of both channels in the context of a student loan program (SOFES) implemented at private universities in Mexico. With regard to the first channel, enrollment, results from the Mexican household survey indicate that financial support has a strong positive effect on university enrollment. Given completion of upper secondary education, the probability of entering higher education rises 24 percent. Two data sourcesare used to investigate the second channel, student performance. Administrative data provided by SOFES are analyzed using a regression-discontinuity design, and survey data enable us to perform a similar analysis using a different control group. Empirical results suggest that SOFES recipients show better academic performance than students without a credit from SOFES. However, the results cannot be interpreted as a purely causal impact of the student loan program, since the impacts also could reflect (self-) selection of students.Primary Education,Public Health Promotion,Health Monitoring&Evaluation,Teaching and Learning,Environmental Economics&Policies,Health Monitoring&Evaluation,Primary Education,Environmental Economics&Policies,Teaching and Learning,Gender and Education
Lung Cancer Screening: The interplay of early detection, treatment, and quality of life in the United States
The first part of this thesis (Chapters 1-3) investigates which treatments lung cancer patients in the United States received before the implementation of lung cancer screening, and how these treatment patterns change as a result of the implementation of lung cancer screening. In the second part of this thesis (Chapters 4-6), the benefits and harms of population-based lung cancer screening in the United States are investigated from different perspectives
Morphological stability for in silico models of avascular tumors
The landscape of computational modeling in Cancer Systems Biology is diverse,
offering a spectrum of models and frameworks, each with its own trade-offs and
advantages. Ideally, models are meant to be useful in refining hypotheses, to
sharpen experimental procedures and, in the longer run, even for applications
in personalized medicine. One of the greatest challenges is to balance model
realism and detail with experimental data to eventually produce useful
data-driven models. We contribute to this quest by developing a transparent,
highly parsimonious, first principle in silico model of a growing avascular
tumor. We initially formulate the physiological considerations and the specific
model within a stochastic cell-based framework. We next formulate a
corresponding mean-field model using partial differential equations which is
amenable to mathematical analysis. Despite a few notable differences between
the two models, we are in this way able to successfully detail the impact of
all parameters in the stability of the growth process and on the eventual tumor
fate of the stochastic model. This facilitates the deduction of Bayesian priors
for a given situation, but also provides important insights into the underlying
mechanism of tumor growth and progression. Although the resulting model
framework is relatively simple and transparent, it can still reproduce the full
range of known emergent behavior. We identify a novel model instability arising
from nutrient starvation and we also discuss additional insight concerning
possible model additions and the effects of those. Thanks to the framework's
flexibility, such additions can be readily included whenever the relevant data
become available.Comment: 27 pages, 9 figure
Lieber, Francis (1798-1872), Author and Professor.
The debate about the origin of the vertebrate dentition has been given fresh fuel by new fossil discoveries and developmental studies of extant animals. Odontodes (teeth or tooth-like structures) can be found in two distinct regions, the 'internal' oropharyngeal cavity and the 'external' skin. A recent hypothesis argues that regularly patterned odontodes is a specific oropharyngeal feature, whereas odontodes in the external skeleton lack this organization. However, this argument relies on the skeletal system of modern chondrichthyans (sharks and their relatives), which differ from other gnathostome (jawed vertebrate) groups in not having dermal bones associated with the odontodes. Their external skeleton is also composed of monoodontode 'placoid scales', whereas the scales of most early fossil gnathostomes are polyodontode, i.e. constructed from several odontodes on a shared bony base. Propagation phase contrast X-ray Synchrotron microtomography (PPC-SRmCT) is used to study the polyodontode scales of the early bony fish Andreolepis hedei. The odontodes constructing a single scale are reconstructed in 3D, and a linear and regular growth mechanism similar to that in a gnathostome dentition is confirmed, together with a second, gap-filling growth mechanism. Acanthodian tooth whorls are described, which show that ossification of the whorl base preceded and probably patterned the development of the dental lamina, in contrast to the condition in sharks where the dental lamina develops early and patterns the dentition. The new findings reveal, for the first time, how polyodontode scales grow in 3D in an extinct bony fish. They show that dentition-like odontode patterning occurs on scales and that the primary patterning unit of a tooth whorl may be the bony base rather than the odontodes it carries. These results contradict the hypothesis that oropharyngeal and external odontode skeletons are fundamentally separate and suggest that the importance of dermal bone interactions to odontode patterning has been underestimated
Semi-Empirical Model for Nano-Scale Device Simulations
We present a new semi-empirical model for calculating electron transport in
atomic-scale devices. The model is an extension of the Extended H\"uckel method
with a self-consistent Hartree potential. This potential models the effect of
an external bias and corresponding charge re-arrangements in the device. It is
also possible to include the effect of external gate potentials and continuum
dielectric regions in the device. The model is used to study the electron
transport through an organic molecule between gold surfaces, and it is
demonstrated that the results are in closer agreement with experiments than ab
initio approaches provide. In another example, we study the transition from
tunneling to thermionic emission in a transistor structure based on graphene
nanoribbons.Comment: 8 pages, 8 figures. Submitted to PR
Pain and Function Recovery Trajectories following Revision Hip Arthroplasty:Short-Term Changes and Comparison with Primary Hip Arthroplasty in the ADAPT Cohort Study
Patients report similar or better pain and function before revision hip arthroplasty than before primary arthroplasty but worse results are reported after revision surgery than after primary surgery. The trajectory of post-operative recovery during the first months and any differences by type of surgery have received little attention. We explored the trajectories of change in pain and function after revision hip arthroplasty to 12-months post-operatively and compare them with those observed after primary hip arthroplasty.This study is a prospective cohort study of patients undergoing primary (n = 80 with 92% for an indication of osteoarthritis) and revision (n = 43) hip arthroplasties. WOMAC pain and function scores and walking speed were collected pre-operatively, at 3 and 12-months post-operatively. Multilevel regression models were used to chart and compare the trajectories of change (0-3 months and 3-12 months) between types of surgery.The improvements in pain and function following revision arthroplasty occurred within the first 3-months with no evidence of further change beyond this initial period. While the pattern of recovery was similar to the one observed after primary arthroplasty, improvements in the first 3-months were smaller after revision compared to primary arthroplasty. Patients listed for revision surgery reported lower pre-operative pain levels but similar post-operative levels compared to those undergoing primary surgery. At 12-months post-operation patients who underwent a revision arthroplasty had not reached the same level of function achieved by those who underwent primary arthroplasty.The post-operative improvements in pain and function are larger following primary hip arthroplasty than following revision hip arthroplasty. Irrespectively of surgery type, most of the improvements occur in the first three post-operative months. More research is required to identify whether the recovery following revision surgery could be improved with specific post-operative interventions
Re-Infection Outcomes Following One- And Two-Stage Surgical Revision of Infected Knee Prosthesis:A Systematic Review and Meta-Analysis
BACKGROUND:Periprosthetic joint infection (PJI) is a serious complication of total knee arthroplasty. Two-stage revision is the most widely used technique and considered as the most effective for treating periprosthetic knee infection. The one-stage revision strategy is an emerging alternative option, however, its performance in comparison to the two-stage strategy is unclear. We therefore sought to ask if there was a difference in re-infection rates and other clinical outcomes when comparing the one-stage to the two-stage revision strategy. OBJECTIVE:Our first objective was to compare re-infection (new and recurrent infections) rates for one- and two-stage revision surgery for periprosthetic knee infection. Our second objective was to compare between the two revision strategies, clinical outcomes as measured by postoperative Knee Society Knee score, Knee Society Function score, Hospital for Special Surgery knee score, WOMAC score, and range of motion. DESIGN:Systematic review and meta-analysis. DATA SOURCES:MEDLINE, EMBASE, Web of Science, Cochrane Library, reference lists of relevant studies to August 2015, and correspondence with investigators. STUDY SELECTION:Longitudinal (prospective or retrospective cohort) studies conducted in generally unselected patients with periprosthetic knee infection treated exclusively by one- or two-stage revision and with re-infection outcomes reported within two years of revision surgery. No clinical trials comparing both revision strategies were identified. REVIEW METHODS:Two independent investigators extracted data and discrepancies were resolved by consensus with a third investigator. Re-infection rates from 10 one-stage studies (423 participants) and 108 two-stage studies (5,129 participants) were meta-analysed using random-effect models after arcsine transformation. RESULTS:The rate (95% confidence intervals) of re-infection was 7.6% (3.4-13.1) in one-stage studies. The corresponding re-infection rate for two-stage revision was 8.8% (7.2-10.6). In subgroup analyses, re-infection rates remained generally similar for several study-level and clinically relevant characteristics. Postoperative clinical outcomes of knee scores and range of motion were similar for both revision strategies. LIMITATIONS:Potential bias owing to the limited number of one-stage revision studies and inability to explore heterogeneity in greater detail. CONCLUSIONS:Available evidence from aggregate published data suggest the one-stage revision strategy may be as effective as the two-stage revision strategy in treating infected knee prostheses in generally unselected patients. Further investigation is warranted. SYSTEMATIC REVIEW REGISTRATION:PROSPERO 2015: CRD42015017327
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