746 research outputs found
The spooky ghost of vectorization
An interesting mechanism for the formation of hairy black holes occurs when a
vector field, non-minimally coupled to a source term, grows from a perturbation
of the vacuum black hole, \textit{aka} vectorization. Its study has, however,
been lacking, in part due to the constant threat of ghost instabilities that
have plagued vector fields. In this work, we show evidence that, in a generic
family of extended-vector-tensor theories where the vector field is
non-minimally coupled to the model's invariant (source term), a spherically
symmetric, vectorized black hole always suffers from ghost instabilities. These
ultimately turn the process of vectorization astrophysically unviable.Comment: 12 page
Who is buying urban condominiums? : a tale of four cities
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references.This thesis is an analysis of the current trend in urban condominium and loft sales in the United States. It focuses specifically on the question of whom, demographically speaking, is buying the incredible influx of new urban residential products that has come onto the market since 2000. There is only anecdotal evidence gathered to date, where some claim that it is the empty-nesters abandoning the suburbs for the convenience of city life. However, there has not been the corresponding drop in suburban population levels or house sale levels to corroborate that hypothesis. Other market participants claim that the sales are primarily to investors, who are either renting or riding appreciation expectations to resell. If that is true, then there are considerable market implications for the future. Others project that it is an urban pied-a-terre trend; however the 2000 census only identifies 3% of the whole housing stock as seasonal, recreational, or second homes. This thesis pools and analyzes recent historical data in four urban downtowns: Atlanta, Boston, Chicago, and San Diego to determine what is happening in each city and to try to discover a national trend. It utilizes raw mortgage origination data, assessor's data, and surveys and interviews with developers and brokers in each of the four designated cities.(cont.) In addition to demographic profiles of buyers, this study determines whether these are second homes, speculative purchases, or complete relocations from outside the city. Ultimately, what can be concluded from this analysis is that a much larger segment of demand for urban condos in Atlanta, Boston, Chicago and San Diego consists of second home purchasers and investors than are counted in the 2000 Census. Surveys of 7849 units indicate 66% owner occupancy, 22% second home purchase plus investors with no plan to rent and finally another 12% investors who rent out their units. Trends are similar across markets, although the Atlanta market is driven by younger buyers and San Diego has the lowest percentage of owner occupants, indicating the most speculative buying.by Robert M. DeLaney and Linda K. Pizzuti.S.M
Bi-Objective Community Detection (BOCD) in Networks using Genetic Algorithm
A lot of research effort has been put into community detection from all
corners of academic interest such as physics, mathematics and computer science.
In this paper I have proposed a Bi-Objective Genetic Algorithm for community
detection which maximizes modularity and community score. Then the results
obtained for both benchmark and real life data sets are compared with other
algorithms using the modularity and MNI performance metrics. The results show
that the BOCD algorithm is capable of successfully detecting community
structure in both real life and synthetic datasets, as well as improving upon
the performance of previous techniques.Comment: 11 pages, 3 Figures, 3 Tables. arXiv admin note: substantial text
overlap with arXiv:0906.061
Rapid detection of copy number variations and point mutations in BRCA1/2 genes using a single workflow by ion semiconductor sequencing pipeline
Molecular analysis of BRCA1 (MIM# 604370) and BRCA2 (MIM #600185) genes is essential for familial breast and ovarian cancer prevention and treatment. An efficient, rapid, cost-effective accurate strategy for the detection of pathogenic variants is crucial. Mutations detection of BRCA1/2 genes includes screening for single nucleotide variants (SNVs), small insertions or deletions (indels), and Copy Number Variations (CNVs). Sanger sequencing is unable to identify CNVs and therefore Multiplex Ligation Probe amplification (MLPA) or Multiplex Amplicon Quantification (MAQ) is used to complete the BRCA1/2 genes analysis. The rapid evolution of Next Generation Sequencing (NGS) technologies allows the search for point mutations and CNVs with a single platform and workflow. In this study we test the possibilities of NGS technology to simultaneously detect point mutations and CNVs in BRCA1/2 genes, using the OncomineTM BRCA Research Assay on Personal Genome Machine (PGM) Platform with Ion Reporter Software for sequencing data analysis (Thermo Fisher Scientific). Comparison between the NGS-CNVs, MLPA and MAQ results shows how the NGS approach is the most complete and fast method for the simultaneous detection of all BRCA mutations, avoiding the usual time consuming multistep approach in the routine diagnostic testing of hereditary breast and ovarian cancers
CLASH-VLT: Testing the Nature of Gravity with Galaxy Cluster Mass Profiles
We use high-precision kinematic and lensing measurements of the total mass
profile of the dynamically relaxed galaxy cluster MACS J1206.2-0847 at
to estimate the value of the ratio between the two scalar
potentials in the linear perturbed Friedmann-Lemaitre-Robertson-Walker
metric.[...] Complementary kinematic and lensing mass profiles were derived
from exhaustive analyses using the data from the Cluster Lensing And Supernova
survey with Hubble (CLASH) and the spectroscopic follow-up with the Very Large
Telescope (CLASH-VLT). Whereas the kinematic mass profile tracks only the
time-time part of the perturbed metric (i.e. only ), the lensing mass
profile reflects the contribution of both time-time and space-space components
(i.e. the sum ). We thus express as a function of the mass
profiles and perform our analysis over the radial range . Using a spherical Navarro-Frenk-White mass profile, which
well fits the data, we obtain \eta(r_{200})=1.01\,_{-0.28}^{+0.31} at the
68\% C.L. We discuss the effect of assuming different functional forms for mass
profiles and of the orbit anisotropy in the kinematic reconstruction.
Interpreting this result within the well-studied modified gravity model,
the constraint on translates into an upper bound to the interaction
length (inverse of the scalaron mass) smaller than 2 Mpc. This tight constraint
on the interaction range is however substantially relaxed when
systematic uncertainties in the analysis are considered. Our analysis
highlights the potential of this method to detect deviations from general
relativity, while calling for the need of further high-quality data on the
total mass distribution of clusters and improved control on systematic effects.Comment: 18 pages, 3 figures, submitted to JCA
Molecular analysis of sarcomeric and non-sarcomeric genes in patients with hypertrophic cardiomyopathy.
Background: Hypertrophic cardiomyopathy (HCM) is a common genetic heart disorder characterized by
unexplained left ventricle hypertrophy associated with non-dilated ventricular chambers. Several genes
encoding heart sarcomeric proteins have been associated to HCM, but a small proportion of HCM patients
harbor alterations in other non-sarcomeric loci. The variable expression of HCM seems influenced by genetic
modifier factors and new sequencing technologies are redefining the understanding of genotype–phenotype
relationships, even if the interpretations of the numerous identified variants pose several challenges.
Methods and results: We investigated 62 sarcomeric and non-sarcomeric genes in 41 HCM cases and in
3 HCM-related disorders patients. We employed an integrated approach that combines multiple tools for
the prediction, annotation and visualization of functional variants. Genotype–phenotype correlations
were carried out for inspecting the involvement of each gene in age onset and clinical variability of HCM. The
80% of the non-syndromic patients showed at least one rare non-synonymous variant (nsSNV) and among
them, 58% carried alterations in sarcomeric loci, 14% in desmosomal and 7% in other non-sarcomeric ones
without any sarcomere change. Statistical analyses revealed an inverse correlation between the number of
nsSNVs and age at onset, and a relationship between the clinical variability and number and type of variants.
Conclusions: Our results extend the mutational spectrum of HCM and contribute in defining the molecular
pathogenesis and inheritance pattern(s) of this condition. Besides, we delineate a specific procedure for the
identification of the most likely pathogenetic variants for a next generation sequencing approach embodied in
a clinical context
X-linked dominant RPGR gene mutation in a familial Coats angiomatosis
Background: Retinitis Pigmentosa (RP) is the most frequent retinal hereditary disease and every kind of transmission pattern has been described. The genetic etiology of RP is extremely heterogeneous and in the last few years the large application of Next Generation Sequencing (NGS) approaches improved the diagnostic yield, elucidating previously unexplained RP causes and new genotype-phenotype correlations. The objective of this study was to reevaluate a previously reported family affected by Coats’-type RP without genetic diagnosis and to describe the new genetic findings. Case presentation: Cohort, prospective, and single-center observational family case. Three individuals of a family, consisting of a mother and four sons, with a Coats phenotype were revaluated after 25 years of clinical follow-up using visual acuity tests, ophthalmoscopy, Goldmann visual field, electroretinography (ERG), and spectral domain-optical coherence tomography (SD-OCT). Specifically, a RP NGS panel was performed on one member of the family and segregation analysis was required for the other affected and unaffected members. NGS analysis disclosed a RPGR (Retinitis Pigmentosa GTPase Regulator) gene truncating variant segregating with the phenotype in all the three affected members. RPGR mutations are reported as causative of an X-linked RP. Conclusions: This is the first reported family with a Coats’-type RP associated to a RPGR mutation and segregating as a dominant X-linked disease, confirming the hypothesis of the genetic origin of this condition and expanding the phenotypic spectrum of diseases caused by RPGR gene mutations. The Authors suggest RPGR gene screening mutations in patients presenting this phenotype
Triple positive breast cancer. A distinct subtype?
Breast cancer is a heterogeneous disease, and within the HER-2 positive subtype this is highly exemplified by the presence of substantial phenotypical and clinical heterogeneity, mostly related to hormonal receptor (HR) expression. It is well known how HER-2 positivity is commonly associated with a more aggressive tumor phenotype and decreased overall survival and, moreover, with a reduced benefit from endocrine treatment. Preclinical studies corroborate the role played by functional crosstalks between HER-2 and estrogen receptor (ER) signaling in endocrine resistance and, more recently, the activation of ER signaling is emerging as a possible mechanism of resistance to HER-2 blocking agents. Indeed, HER-2 positive breast cancer heterogeneity has been suggested to underlie the variability of response not only to endocrine treatments, but also to HER-2 blocking agents. Among HER-2 positive tumors, HR status probably defines two distinct subtypes, with dissimilar clinical behavior and different sensitivity to anticancer agents. The triple positive subtype, namely, ER/PgR/Her-2 positive tumors, could be considered the subset which most closely resembles the HER-2 negative/HR positive tumors, with substantial differences in biology and clinical outcome. We argue on whether in this subgroup the "standard" treatment may be considered, in selected cases, i.e., small tumors, low tumor burden, high expression of both hormonal receptors, an overtreatment. This article review the existing literature on biologic and clinical data concerning the HER-2/ER/PgR positive tumors, in an attempt to better define the HER-2 subtypes and to optimize the use of HER-2 targeted agents, chemotherapy and endocrine treatments in the various subsets
Financial Analysis of Dalbavancin for Acute Bacterial Skin and Skin Structure Infections for Self-Pay Patients
© 2020, The Author(s). Introduction: Acute bacterial skin and skin structure infections (ABSSSI) are an increasing cause of admission in the self-pay population. We previously reported that patients with ABSSSI discharged to receive dalbavancin showed a decreased length of stay (LOS) and total direct costs without increasing 30-day readmission rate. For patients who are financially eligible, a dalbavancin vial replacement program can offset costs. The objective of this study was to determine cost differences in treating ABSSSI in self-pay inpatients discharged to receive dalbavancin compared to standard of care (SOC). Methods: This retrospective cohort within a community health system compared self-pay adult inpatients with ABSSSI from February 3, 2016 to August 5, 2019 discharged to receive dalbavancin at an outpatient infusion center with SOC intravenous antibiotics. Patients were included with cellulitis, abscess, or postoperative wound infections diagnoses on the basis of International Classification of Disease, Tenth Revision (ICD-10) codes. Excluded populations were patients without dalbavancin vial replacement performed, pregnant, infections caused exclusively by gram-negative bacteria or fungi, or ICD-10 codes not consistent with ABSSSI. The primary outcome was direct cost of hospital stay. Secondary outcomes included length of stay (LOS), 30-day readmission rates, adverse events (AE), and indirect hospital costs. On the basis of previous studies, a one-sided Student’s t test was performed on financial data. Results: Twelve dalbavancin and 263 SOC patients met inclusion criteria. Direct cost (4010, p = 0.105) and indirect hospital cost (3646 , p = 0.162) per patient were less in the dalbavancin group. There was no significant difference between median LOS (4 vs 4, p = 0.888), AE (0% vs 14.8%), and 30-day readmission rates for dalbavancin vs SOC group (8.3% vs 7.2%, p = 0.604). Conclusion: Self-pay patients with ABSSSI discharged to receive dalbavancin with vial replacement resulted in decreased direct and indirect costs per patient with similar 30-day readmission rates, AE, and LOS. More studies targeted toward this population are warranted to determine ultimate benefit
CLASH-VLT: The inner slope of the MACS J1206.2-0847 mass density profile
The inner slope gammaDM of the dark matter (DM) density profile of
cosmological halos carries information about the properties of DM and/or
baryonic processes affecting the halo gravitational potential. Cold DM
cosmological simulations predict steep inner slopes, gammaDM>~1. We test this
prediction on the MACS J1206.2-0847 cluster at redshift z=0.44, whose DM
density profile was claimed to be cored at the center. We determine the cluster
DM density profile from 2 kpc from the cluster center to the virial radius (~2
Mpc), using the velocity distribution of ~500 cluster galaxies and the velocity
dispersion profile of the Brightest Cluster Galaxy (BCG), obtained from
VIMOS@VLT and MUSE@VLT data. We solve the Jeans equation of dynamical
equilibrium using an upgraded version of the MAMPOSSt method. The total mass
profile is modeled as a sum of a generalized-NFW profile that describes the DM
component, allowing for a free inner slope of the density profile, a Jaffe
profile that describes the BCG stellar mass component, and a non-parametric
baryonic profile that describes the sum of the remaining galaxy stellar mass
and of the hot intra-cluster gas mass. Our total mass profile is in remarkable
agreement with independent determinations based on X-ray observations and
strong lensing. We find gammaDM=0.7 -0.1 +0.2 (68% confidence levels),
consistent with predictions from recent LambdaCDM cosmological numerical
simulations.Comment: Submitted to ApJ on June, 1st 2023. 14 pages, 9 figure
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