Acute gastroenteritis in Hong Kong: A population-based telephone survey

A population-based telephone survey of acute gastroenteritis (AG) was conducted in Hong Kong from August 2006 to July 2007. Study subjects were recruited through random digit-dialling with recruitments evenly distributed weekly over the 1-year period. In total, 3743 completed questionnaires were obtained. An AG episode is defined as diarrhoea 3 times or any vomiting in a 24-h period during the 4 weeks prior to interview, in the absence of known non-infectious causes. The prevalence of AG reporting was 7%. An overall rate of 091 (95% CI 081-101) episodes per person-year was observed with women having a slightly higher rate (094, 95% CI 079-108) than men (088, 95% CI 073-104). The mean duration of illness was 36 days (s.d.=552). Thirty-nine percent consulted a physician, 19% submitted a stool sample for testing, and 26% were admitted to hospital. Of the subjects aged 15 ≥ years, significantly more of those with AG reported eating raw oysters (OR 24, 95% CI 13-44), buffet meals (OR 18, 95% CI 13-25), and partially cooked beef (OR 18, 95% CI 12-27) in the previous 4 weeks compared to the subjects who did not report AG. AG subjects were also more likely to have had hot pot, salad, partially cooked or raw egg or fish, sushi, sashimi, and snacks bought at roadside in the previous 4 weeks. This first population-based study on the disease burden of AG in Asia showed that the prevalence of AG in Hong Kong is comparable to that experienced in the West. The study also revealed some risky eating practices that are more prevalent in those affected with AG. Copyright © 2009 Cambridge University Press.published_or_final_versio

Subcooled flow boiling heat transfer and critical heat flux in water-based nanofluids at low pressure

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 285-290).A nanofluid is a colloidal suspension of nano-scale particles in water, or other base fluids. Previous pool boiling studies have shown that nanofluids can improve the critical heat flux (CHF) by as much as 200%. In this study, subcooled flow boiling heat transfer and CHF experiments were performed with low concentrations of alumina, zinc oxide, and diamond nanoparticles in water (< 0.1 % by volume) at atmospheric pressure. It was found that for comparable test conditions the values of the nanofluid and water heat transfer coefficient (HTC) are similar (within ±20%). The HTC increased with mass flux and heat flux for water and nanofluids alike, as expected in flow boiling. The CHF tests were conducted at 0.1 MPa and at three different mass fluxes (1500, 2000, 2500 kg/m2s) under subcooled conditions. The maximum CHF enhancement was 53%, 53% and 38% for alumina, zinc oxide and diamond, respectively, always obtained at the highest mass flux. The measurement uncertainty of the CHF was less than 6.2%. A post-mortem analysis of the boiling surface reveals that its morphology is altered by deposition of the particles during nanofluids boiling. A confocal-microscopy-based examination of the test section revealed nanoparticles deposition not only changes the number of micro-cavities on the surface, but also the surface wettability. A simple model was used to estimate the ensuing nucleation site density changes, but no definitive correlation between the nucleation site density and the heat transfer coefficient data could be found.(cont.) Wettability of the surface was substantially increased for heater coupons boiled in alumina and zinc oxide nanofluids, and such wettability increase seems to correlate reasonably well with the observed marked CHF enhancement for the respective nanofluids. Interpretation of the experimental data was conducted in light of the governing surface parameters and existing models. It was found that no single parameter could explain the observed HTC or CHF phenomena. The existing models were limited in studying the surface effects, suggesting that more accurate models incorporating surface effects need to be developed. Finally, the research activities performed in this thesis help identify the research gaps and indicate future research directions.by Sung Joon Kim.Ph.D

Pool boiling heat transfer characteristics of nanofluids

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (leaves 79-83).Nanofluids are engineered colloidal suspensions of nanoparticles in water, and exhibit a very significant enhancement (up to 200%) of the boiling Critical Heat Flux (CHF) at modest nanoparticle concentrations (50.1% by volume). Since CHF is the upper limit of nucleate boiling, such enhancement offers the potential for major performance improvement in many practical applications that use nucleate boiling as their prevalent heat transfer mode. The nuclear applications considered are main reactor coolant for PWR, coolant for the Emergency Core Cooling System (ECCS) of both PWR and BWR, and coolant for in-vessel retention of the molten core during severe accidents in high-power-density LWR. To implement such applications it is necessary to understand the fundamental boiling heat transfer characteristics of nanofluids. The nanofluids considered in this study are dilute dispersions of alumina, zirconia, and silica nanoparticles in water. Several key parameters affecting heat transfer (i.e., boiling point, viscosity, thermal conductivity, and surface tension) were measured and, consistently with other nanofluid studies, were found to be similar to those of pure water. However, pool boiling experiments showed significant enhancements of CHF in the nanofluids. Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometry (EDS) analyses revealed that buildup of a porous layer of nanoparticles on the heater surface occurred during nucleate boiling. This layer significantly improves the surface wettability, as shown by measured changes in the static contact angle on the nanofluid-boiled surfaces compared with the pure-water-boiled surfaces. It is hypothesized that surface wettability improvement may be responsible for the CHF enhancement.by Sung Joong Kim.S.M

Bio-inspired collective analog computation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 101-102).In this thesis, I present electronic circuit systems that mimic collective analog com- putation found in biology. By combining the advantages of analog and digital computation, these systems can lead to highly complex, rapid, and energy-efficient systems such as an analog supercomputer that is capable of simulating a great number of bio- chemical reactions in cells. To this end, I first implement a neuron-inspired collective analog adder in a standard 0.5 [mu]m CMOS process. It serves as a prototype system that visualizes fundamental design ideas and techniques for building a collective analog computation system. Next, I build a cell-inspired analog circuit system which efficiently models bacterial genetic circuits in a cell, which can provide a powerful modeling and simulation tool for the design and analysis of circuits in synthetic and systems biology.by Sung Sik Woo.S.M

Adiabatic Transfer of Electrons in Coupled Quantum Dots

We investigate the influence of dissipation on one- and two-qubit rotations in coupled semiconductor quantum dots, using a (pseudo) spin-boson model with adiabatically varying parameters. For weak dissipation, we solve a master equation, compare with direct perturbation theory, and derive an expression for the `fidelity loss' during a simple operation that adiabatically moves an electron between two coupled dots. We discuss the possibility of visualizing coherent quantum oscillations in electron `pump' currents, combining quantum adiabaticity and Coulomb blockade. In two-qubit spin-swap operations where the role of intermediate charge states has been discussed recently, we apply our formalism to calculate the fidelity loss due to charge tunneling between two dots.Comment: 13 pages, 8 figures, to appear in Phys. Rev.

Intra- and interfamily phenotypic diversity in pain syndromes associated with a gain-of-function variant of NaV1.7

<p>Abstract</p> <p>Background</p> <p>Sodium channel Na_V1.7 is preferentially expressed within dorsal root ganglia (DRG), trigeminal ganglia and sympathetic ganglion neurons and their fine-diamter axons, where it acts as a threshold channel, amplifying stimuli such as generator potentials in nociceptors. Gain-of-function mutations and variants (single amino acid substitutions) of Na_V1.7 have been linked to three pain syndromes: Inherited Erythromelalgia (IEM), Paroxysmal Extreme Pain Disorder (PEPD), and Small Fiber Neuropathy (SFN). IEM is characterized clinically by burning pain and redness that is usually focused on the distal extremities, precipitated by mild warmth and relieved by cooling, and is caused by mutations that hyperpolarize activation, slow deactivation, and enhance the channel ramp response. PEPD is characterized by perirectal, periocular or perimandibular pain, often triggered by defecation or lower body stimulation, and is caused by mutations that severely impair fast-inactivation. SFN presents a clinical picture dominated by neuropathic pain and autonomic symptoms; gain-of-function variants have been reported to be present in approximately 30% of patients with biopsy-confirmed idiopathic SFN, and functional testing has shown altered fast-inactivation, slow-inactivation or resurgent current. In this paper we describe three patients who house the Na_V1.7/I228M variant.</p> <p>Methods</p> <p>We have used clinical assessment of patients, quantitative sensory testing and skin biopsy to study these patients, including two siblings in one family, in whom genomic screening demonstrated the I228M Na_V1.7 variant. Electrophysiology (voltage-clamp and current-clamp) was used to test functional effects of the variant channel.</p> <p>Results</p> <p>We report three different clinical presentations of the I228M Na_V1.7 variant: presentation with severe facial pain, presentation with distal (feet, hands) pain, and presentation with scalp discomfort in three patients housing this Na_V1.7 variant, two of which are from a single family. We also demonstrate that the Na_V1.7/I228M variant impairs slow-inactivation, and produces hyperexcitability in both trigeminal ganglion and DRG neurons.</p> <p>Conclusion</p> <p>Our results demonstrate intra- and interfamily phenotypic diversity in pain syndromes produced by a gain-of-function variant of Na_V1.7.</p

Diet, vegetarian food and prostate carcinoma among men in Taiwan

In a case–control study in a veterans hospital in Taiwan, we compared 237 histology-confirmed prostate carcinoma cases with 481 controls, frequency matched by age, for their consumption of vegetarian food, namely soybean products, rice, wheat protein and other vegetables. The multivariable logistic regression analysis showed a significant association with such food (odds ratio (OR)=0.67, 95% confidence interval (CI)=0.47, 0.94). This beneficial effect presented for men with body mass index (BMI) ⩽25 kg m−2 (OR=0.50, 95% CI=0.32, 0.76) but not for men with greater BMI. The OR of prostate carcinoma for men with BMI ⩽25 kg m−2 was 1.74 (95% CI=1.21, 2.51), compared with men with higher BMI (>25 kg m−2). Other significant risk factors associated with the disease included higher income (OR=2.40, 95% CI=1.07, 5.42), physical activity (OR=1.75, 95% CI=1.08, 2.83), being married (OR=2.49, 95% CI=1.40, 4.43) and coffee consumption (OR=1.88, 95% CI=1.07, 3.30). Stratified analysis also showed that the consumption of fish/shellfish had an adverse association for men with higher BMI. This study suggests that the intake of the low fat local vegetarian food has a protective effect against prostate carcinoma for thin men in this study population

Burgers' Flows as Markovian Diffusion Processes

We analyze the unforced and deterministically forced Burgers equation in the framework of the (diffusive) interpolating dynamics that solves the so-called Schr\"{o}dinger boundary data problem for the random matter transport. This entails an exploration of the consistency conditions that allow to interpret dispersion of passive contaminants in the Burgers flow as a Markovian diffusion process. In general, the usage of a continuity equation $\partial_t\rho =-\nabla (\vec{v}\rho)$, where $\vec{v}=\vec{v}(\vec{x},t)$ stands for the Burgers field and $\rho$ is the density of transported matter, is at variance with the explicit diffusion scenario. Under these circumstances, we give a complete characterisation of the diffusive transport that is governed by Burgers velocity fields. The result extends both to the approximate description of the transport driven by an incompressible fluid and to motions in an infinitely compressible medium. Also, in conjunction with the Born statistical postulate in quantum theory, it pertains to the probabilistic (diffusive) counterpart of the Schr\"{o}dinger picture quantum dynamics.Comment: Latex fil

Amyotrophic Lateral Sclerosis Is Associated with Hypolipidemia at the Presymptomatic Stage in Mice

OBJECTIVE: To demonstrate that hypolipidemia is a typical feature of the mouse model of amyotrophic lateral sclerosis (ALS) and to assess the association between hypolipidemia and disease stage, dietary intake, and sex. METHODS: We compared daily dietary intake, body weight, and serumlipid and glucose levels in ALS mice and wild-type controls at different stages of the disease. FINDINGS: Total cholesterol low-density lipoprotein (LDL) and LDL/high-density lipoprotein (HDL) ratio were significantly lower in ALS mice compared with controls. Subgroup analysis revealed that the incidence of hypolipidemia was significantly greater in male, but not female, ALS mice compared with control mice and that hypolipidemia was present at the presymptomatic stage of the disease. This hypolipidemia can be found without a decrease in the serum levels of other energy sources, such as glucose, in the presymptomatic stage. CONCLUSIONS: Hypolipidemia is present at the presymptomatic stage of the ALS mouse model in the absence of malnutrition, significant neuromuscular degeneration or regeneration, and respiratory difficulty. Our findings suggest that hypolipidemia might be associated with the pathomechanism of ALS and/or lipid-specific metabolism rather than simply an epiphenomenon of neuromuscular degeneration or energy imbalance

Dicke Effect in the Tunnel Current through two Double Quantum Dots

We calculate the stationary current through two double quantum dots which are interacting via a common phonon environment. Numerical and analytical solutions of a master equation in the stationary limit show that the current can be increased as well as decreased due to a dissipation mediated interaction. This effect is closely related to collective, spontaneous emission of phonons (Dicke super- and subradiance effect), and the generation of a `cross-coherence' with entanglement of charges in singlet or triplet states between the dots. Furthermore, we discuss an inelastic `current switch' mechanism by which one double dot controls the current of the other.Comment: 12 pages, 6 figures, to appear in Phys. Rev.