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Host Genomics in Infectious Diseases
Mark Loeb 대한감염학회 2013 Infection and Chemotherapy Vol.45 No.3
Understanding mechanisms by which genetic variants predispose to complications of infectious diseases can lead to important benefits including the development of biomarkers to prioritize vaccination or prophylactic therapy. Family studies, candidate genes in animal models, and the absence of well-defined risks where the complications are rare all can point to genetic predisposition. The most common approach to assessing genetic risk is to conduct an association study, which is a case control study using either a candidate gene approach or a genome wide approach. Although candidate gene variants may focus on potentially causal variants, because other variants across the genome are not tested these studies frequently cannot be replicated. Genome wide association studies need a sizable sample and usually do not identify causal variants but variants which may be in linkage disequilibrium to the actual causal variant. There are many pitfalls that can lead to bias in such studies, including misclassification of cases and controls, use of improper phenotypes, and genotyping errors. These studies have been limited to common genes and rare variants may not be detected. As the use of next generation sequencing becomes more common, it can be anticipated that more variants will be confirmed. The purpose of this review article is to address the issue of genomics in infectious diseases with an emphasis on the host. Although there are a plentitude of studies that focus on the molecular characteristics of pathogens, there are far fewer studies that address the role of human genetics in the predisposition to infection or more commonly its complications. This paper will review both the approaches used to study host genetics in humans and the pitfalls associated with some of these methods. The focus will be on human disease and therefore discussion of the use of animal models will be limited to those where there are genes that have been replicated in humans. The paper will focus on common genetic variants that account for complex traits such as infectious diseases using examples from flaviviruses.
Electromagnetic Forces on a Relativistic Spacecraft in the Interstellar Medium
Hoang, Thiem,Loeb, Abraham American Astronomical Society 2017 The Astrophysical journal Vol.848 No.1
<P>A relativistic spacecraft of the type envisioned by the Breakthrough Starshot initiative will inevitably become charged through collisions with interstellar particles and UV photons. Interstellar magnetic fields would therefore deflect the trajectory of the spacecraft. We calculate the expected deflection for typical interstellar conditions. We also find that the charge distribution of the spacecraft is asymmetric, producing an electric dipole moment. The interaction between the moving electric dipole and the interstellar magnetic field is found to produce a large torque, which can result in fast oscillation of the spacecraft around the axis perpendicular to the direction of motion, with a period of similar to 0.5 hr. We then study the spacecraft rotation arising from impulsive torques by dust bombardment. Finally, we discuss the effect of the spacecraft rotation and suggest several methods to mitigate it.</P>
Olivier Senese,Edward Boutremans,Caroline Gossiaux,Isabelle Loeb,Didier Dequanter 대한두개안면성형외과학회 2018 Archives of Craniofacial Surgery Vol.19 No.2
Background: The aim of our retrospective study is to evaluate the management of isolated orbital floor fractures considering the clinical, functional and aesthetic results according to the surgical approach and the type of materials used. Methods: Retrospectively, clinical, radiological, surgical, and ophthalmological data from 79 patients were collected from January 2010 to December 2016. Furthermore, included patients were interrogated on functional and aesthetic satisfaction. Results: The main causes of trauma were physical aggression followed by accidents. The median time between trauma and surgery was 4 days. The most common surgical approaches were the subciliary and the transconjunctival ones. Alloplastic materials were used in 75 patients. In two patients, we used a combination of two grafts. Patients experienced minor immediate complications. On follow-ups, none of our patients suffered from ocular movement restrictions. Patients treated by subciliary approach had higher risk of retractile scaring compared to other surgical approaches. In our study, patients agreed to complete a questionnaire assessing functional and aesthetic outcomes with a high satisfaction score. No association between the implant material used and the results has been assessed. Conclusion: This study describes the results of orbital floor reconstructions. Despite a variety of materials used and surgical approaches performed, we believe that the transconjunctival approach is the most suitable option with a high satisfaction score.
The Interaction of Relativistic Spacecrafts with the Interstellar Medium
Hoang, Thiem,Lazarian, A.,Burkhart, Blakesley,Loeb, Abraham American Astronomical Society 2017 The Astrophysical journal Vol.837 No.1
<P>The Breakthrough Starshot initiative aims to launch a gram-scale spacecraft to a speed of nu similar to 0.2c, capable of reaching the nearest star system, alpha Centauri, in about 20 years. However, a critical challenge for the initiative is the damage to the spacecraft by interstellar gas and dust during the journey. In this paper, we quantify the interaction of a relativistic spacecraft with gas and dust in the interstellar medium (ISM). For gas bombardment, we find that damage by track formation due to heavy elements is an important effect. We find that gas bombardment can potentially damage the surface of the spacecraft to a depth of similar to 0.1 mm for quartz material after traversing a gas column of N-H similar to 2 x 10(18) cm(-2) along the path to alpha Centauri, whereas the effect is much weaker for graphite material. The effect of dust bombardment erodes the spacecraft surface and produces numerous craters due to explosive evaporation of surface atoms. For a spacecraft speed nu = 0.2c, we find that dust bombardment can erode a surface layer of similar to 0.5 mm thickness after the spacecraft has swept a column density of N-H similar to 3 x 10(17) cm(-2) assuming the standard gas-to-dust ratio of the ISM. Dust bombardment also damages the spacecraft surface by modifying the material structure through melting. We calculate the equilibrium surface temperature due to collisional heating by gas atoms as well as the temperature profile as a function of depth into the spacecraft. Our quantitative results suggest methods for damage control, and we highlight possibilities for shielding strategies and protection of the spacecraft.</P>
Soumagnac, M. T.,Barkana, R.,Sabiu, C. G.,Loeb, A.,Ross, A. J.,Abdalla, F. B.,Balan, S. T.,Lahav, O. American Physical Society 2016 Physical Review Letters Vol.116 No.20
<P>Baryon acoustic oscillations in the early Universe are predicted to leave an as yet undetected signature on the relative clustering of total mass versus luminous matter. A detection of this effect would provide an important confirmation of the standard cosmological paradigm and constrain alternatives to dark matter as well as nonstandard fluctuations such as compensated isocurvature perturbations (CIPs). We conduct the first observational search for this effect, by comparing the number-weighted and luminosity-weighted correlation functions, using the SDSS-III BOSS Data Release 10 CMASS sample. When including CIPs in our model, we formally obtain evidence at 3.2 sigma of the relative clustering signature and a limit that matches the existing upper limits on the amplitude of CIPs. However, various tests suggest that these results are not yet robust, perhaps due to systematic biases in the data. The method developed in this Letter used with more accurate future data such as that from DESI, is likely to confirm or disprove our preliminary evidence.</P>