893 research outputs found
Scaling of Clusters and Winding Angle Statistics of Iso-height Lines in two-dimensional KPZ Surface
We investigate the statistics of Iso-height lines of (2+1)-dimensional
Kardar-Parisi-Zhang model at different level sets around the mean height in the
saturation regime. We find that the exponent describing the distribution of the
height-cluster size behaves differently for level cuts above and below the mean
height, while the fractal dimensions of the height-clusters and their
perimeters remain unchanged. The winding angle statistics also confirms again
the conformal invariance of these contour lines in the same universality class
of self-avoiding random walks (SAWs).Comment: 5 pages, 5 figure
Linear Relationship Statistics in Diffusion Limited Aggregation
We show that various surface parameters in two-dimensional diffusion limited
aggregation (DLA) grow linearly with the number of particles. We find the ratio
of the average length of the perimeter and the accessible perimeter of a DLA
cluster together with its external perimeters to the cluster size, and define a
microscopic schematic procedure for attachment of an incident new particle to
the cluster. We measure the fractal dimension of the red sites (i.e., the sites
upon cutting each of them splits the cluster) equal to that of the DLA cluster.
It is also shown that the average number of the dead sites and the average
number of the red sites have linear relationships with the cluster size.Comment: 4 pages, 5 figure
Conformal Curves on Surface
We have studied the iso-height lines on the surface as a
physical candidate for conformally invariant curves. We have shown that these
lines are conformally invariant with the same statistics of domain walls in the
critical Ising model. They belong to the family of conformal invariant curves
called Schramm-Loewner evolution (or ), with diffusivity of
. This can be regarded as the first experimental observation of
SLE curves. We have also argued that Ballistic Deposition (BD) can serve as a
growth model giving rise to contours with similar statistics at large scales.Comment: 4 pages, 6 figures. accepted in PR
Inferring gene regulatory networks from gene expression data by a dynamic Bayesian network-based model
Enabled by recent advances in bioinformatics, the inference of gene regulatory networks (GRNs) from gene expression data has garnered much interest from researchers. This is due to the need of researchers to understand the dynamic behavior and uncover the vast information lay hidden within the networks. In this regard, dynamic Bayesian network (DBN) is extensively used to infer GRNs due to its ability to handle time-series microarray data and modeling feedback loops. However, the efficiency of DBN in inferring GRNs is often hampered by missing values in expression data, and excessive computation time due to the large search space whereby DBN treats all genes as potential regulators for a target gene. In this paper, we proposed a DBN-based model with missing values imputation to improve inference efficiency, and potential regulators detection which aims to lessen computation time by limiting potential regulators based on expression changes. The performance of the proposed model is assessed by using time-series expression data of yeast cell cycle. The experimental results showed reduced computation time and improved efficiency in detecting gene-gene relationships
Inferring gene regulatory networks from gene expression data by a dynamic Bayesian network-based model
Enabled by recent advances in bioinformatics, the inference of gene regulatory networks (GRNs) from gene expression data has garnered much interest from researchers. This is due to the need of researchers to understand the dynamic behavior and uncover the vast information lay hidden within the networks. In this regard, dynamic Bayesian network (DBN) is extensively used to infer GRNs due to its ability to handle time-series microarray data and modeling feedback loops. However, the efficiency of DBN in inferring GRNs is often hampered by missing values in expression data, and excessive computation time due to the large search space whereby DBN treats all genes as potential regulators for a target gene. In this paper, we proposed a DBN-based model with missing values imputation to improve inference efficiency, and potential regulators detection which aims to lessen computation time by limiting potential regulators based on expression changes. The performance of the proposed model is assessed by using time-series expression data of yeast cell cycle. The experimental results showed reduced computation time and improved efficiency in detecting gene-gene relationships
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Laparoscopic Radiofrequency Ablation of Uterine Leiomyomas: Clinical Outcomes during Early Adoption into Surgical Practice.
STUDY OBJECTIVE:To assess surgical outcomes, clinical effectiveness, and gynecologist experience of introducing laparoscopic radiofrequency ablation (RFA) of leiomyomas into surgical practice. DESIGN:Uncontrolled clinical trial. SETTING:Five academic medical centers across California. PATIENTS:Premenopausal women with symptomatic uterine leiomyomas, uterus size ≤16 weeks size, and all leiomyomas ≤10 cm with no more than 6 total leiomyomas. INTERVENTIONS:Laparoscopic RFA of leiomyomas. MEASUREMENTS AND MAIN RESULTS:We assessed intraoperative complications, blood loss, operative time, and adverse events. Gynecologists reported the operative difficulty and need for further training after each case. Participants reported leiomyoma symptoms preoperatively and at 6 and 12 weeks after surgery. We analyzed all outcome data from the first case performed by gynecologists with no previous RFA experience. Patient demand for RFA was high, but poor insurance authorization prevented 74% of eligible women from trial participation; 26 women underwent surgery and were enrolled. The mean age of the participants was 41.5 ± 4.9 years. The mean operating time was 153 ± 51 minutes, and mean estimated blood loss was 24 ± 40 cc. There were no intraoperative complications and no major adverse events. Menstrual bleeding, sexual function, and quality of life symptoms improved significantly from baseline to 12 weeks, with a 25 ± 18-point, or 47%, decrease in the Leiomyoma Symptom Severity Score. After the first procedure, the mean difficulty score was 6 (95% confidence interval [CI], 4-7.5) on a 10-point scale, and 89% of surgeons felt "very or somewhat" confident in performing laparoscopic RFA. The difficulty score decreased to 4.25 (95% CI, 1.2-6) after the fourth procedure, with all gynecologists reporting surgical confidence. CONCLUSION:Laparoscopic RFA of leiomyomas can be introduced into surgical practice with good clinical outcomes for patients. Gynecologists with no previous experience are able to gain confidence and skill with the procedure in fewer than 5 cases
Three Dimensional Ising Model, Percolation Theory and Conformal Invariance
The fractal structure and scaling properties of a 2d slice of the 3d Ising
model is studied using Monte Carlo techniques. The percolation transition of
geometric spin (GS) clusters is found to occur at the Curie point, reflecting
the critical behavior of the 3d model. The fractal dimension and the winding
angle statistics of the perimeter and external perimeter of the geometric spin
clusters at the critical point suggest that, if conformally invariant in the
scaling limit, they can be described by the theory of Schramm-Loewner evolution
(SLE_\kappa) with diffusivity of \kappa=5 and 16/5, respectively, putting them
in the same universality class as the interfaces in 2d tricritical Ising model.
It is also found that the Fortuin-Kasteleyn (FK) clusters associated with the
cross sections undergo a nontrivial percolation transition, in the same
universality class as the ordinary 2d critical percolation.Comment: 5 pages, 5 figures, accepted for publication in EuroPhysics Letters
(EPL
Ethical and practical considerations for mitigating risks to sexual partners during analytical treatment interruptions in HIV cure-related research
Background: Background: Analytical treatment interruptions (ATIs) in HIV cure-related research can result in trial participants becoming viremic with HIV, placing HIV-negative sexual partners at elevated risk of acquiring HIV. Objective: Objective:Our study aimed to generate ethical and practical considerations for designing and implementing appropriate risk mitigation strategies to reduce unintended HIV transmission events during ATIs. Methods: Methods: We conducted 21 in-depth interviews with five types of informants: bioethicists, community members, biomedical HIV cure researchers, socio-behavioral scientists/epidemiologists, and HIV care providers. We used conventional content analysis to analyze the data and generate considerations. Results: Results: Key findings include: 1) Ethical permissibility of ATI trials depends on due diligence and informed consent to mitigate risks to participants and their sexual partners; 2) Participants should receive adequate support and/or counseling if they choose to disclose ATI participation to their partners; 3) Measures to protect sexual partners of trial participants from HIV transmission during ATIs should include referral to and/or provision of pre-exposure prophylaxis, as well as other available means of preventing HIV transmission; 4) There is uncertainty regarding the appropriate management of emerging sexually transmitted infections during ATI trials and possible protection measures for multiple and/or anonymous partners of ATI trial participants. Conclusion: Conclusion: While there is no way to completely eliminate the risk of HIV transmission to sexual partners during ATIs, HIV cure trialists and sponsors should consider the ethical concerns related to the sexual partners of ATI participants. Doing so is essential to ensuring the welfare of participants, their partners and the trustworthiness of research
Who will use pre-exposure prophylaxis (PrEP) and why?: Understanding PrEP awareness and acceptability amongst men who have sex with men in the UK – a mixed methods study
Background:
Recent clinical trials suggest that pre-exposure prophylaxis (PrEP) may reduce HIV transmission by up to 86% for men who have sex with men (MSM), whilst relatively high levels of PrEP acceptability have been reported to date. This study examines PrEP awareness amongst sub-groups of MSM communities and acceptability amongst MSM in a low prevalence region (Scotland, UK), using a mixed methods design.
Methods:
Quantitative surveys of n = 690 MSM recruited online via social and sociosexual media were analysed using descriptive statistics and multivariate logistic regression. In addition, n = 10 in-depth qualitative interviews with MSM were analysed thematically.
Results:
Under one third (29.7%) of MSM had heard of PrEP, with awareness related to living in large cities, degree level education, commercial gay scene use and reporting an HIV test in the last year. Just under half of participants (47.8%) were likely to use PrEP if it were available but there was no relationship between PrEP acceptability and previous PrEP awareness. Younger men (18–25 years) and those who report higher risk UAI were significantly more likely to say they would use PrEP. Qualitative data described specific PrEP scenarios, illustrating how risk, patterns of sexual practice and social relationships could affect motivation for and nature of PrEP use.
Conclusion:
These findings suggest substantial interest PrEP amongst MSM reporting HIV risk behaviours in Scotland. Given the Proud results, there is a strong case to investigate PrEP implementation within the UK. However, it appears that disparities in awareness have already emerged along traditional indicators of inequality. Our research identifies the need for comprehensive support when PrEP is introduced, including a key online component, to ensure equity of awareness across diverse MSM communities (e.g. by geography, education, gay scene use and HIV proximity), as well as to responding to the diverse informational and sexual health needs of all MSM communities
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