Experimental Studies for the Detection of Protein in Trace Amounts Quarterly Status Report, 1 Mar. - 31 May 1965

Methods for separating inorganic compounds from organic materials in investigation of trace proteins in soil

Crystal lattice properties fully determine short-range interaction parameters for alkali and halide ions

Accurate models of alkali and halide ions in aqueous solution are necessary for computer simulations of a broad variety of systems. Previous efforts to develop ion force fields have generally focused on reproducing experimental measurements of aqueous solution properties such as hydration free energies and ion-water distribution functions. This dependency limits transferability of the resulting parameters because of the variety and known limitations of water models. We present a solvent-independent approach to calibrating ion parameters based exclusively on crystal lattice properties. Our procedure relies on minimization of lattice sums to calculate lattice energies and interionic distances instead of equilibrium ensemble simulations of dense fluids. The gain in computational efficiency enables simultaneous optimization of all parameters for Li+, Na+, K+, Rb+, Cs+, F-, Cl-, Br-, and I- subject to constraints that enforce consistency with periodic table trends. We demonstrate the method by presenting lattice-derived parameters for the primitive model and the Lennard-Jones model with Lorentz-Berthelot mixing rules. The resulting parameters successfully reproduce the lattice properties used to derive them and are free from the influence of any water model. To assess the transferability of the Lennard-Jones parameters to aqueous systems, we used them to estimate hydration free energies and found that the results were in quantitative agreement with experimentally measured values. These lattice-derived parameters are applicable in simulations where coupling of ion parameters to a particular solvent model is undesirable. The simplicity and low computational demands of the calibration procedure make it suitable for parametrization of crystallizable ions in a variety of force fields.Comment: 9 pages, 5 table

Bowel Perforation Secondary to Illegally Induced Abortion: a Tertiary Hospital Experience in Tanzania.

Bowel perforation though rarely reported is a serious complication of induced abortion, which is often performed illegally by persons without any medical training in developing countries. A sudden increase in the number of patients in our centre in recent years prompted the authors to analyze this problem. The study was conducted to describe our own experiences in the surgical management of these patients. This was a retrospective study involving patients who were jointly managed by the surgical and gynecological teams at Bugando Medical Centre (BMC) for bowel perforation secondary to illegally induced abortion from January 2002 to December 2011. The statistical analysis was performed using SPSS version 17.0. A total of 68 patients (representing 4.2% of cases) were enrolled in the study. Their ages ranged from 14 to 45 years with a median age of 21 years. Majority of patients were, secondary school students/leavers (70.6%), unmarried (88.2%), nulliparous (80.9%), unemployed (82.4%) and most of them were dependent member of the family. Previous history of contraceptive use was reported in only 14.7% of cases. The majority of patients (79.4%) had procured the abortion in the 2nd trimester. Dilatation and curettage (82.4%) was the most common reported method used in procuring abortion. The interval from termination of pregnancy to presentation in hospital ranged from 1 to 14 days (median 6 days ). The ileum (51.5%) and sigmoid colon (22.1%) was the most common portions of the bowel affected. Resection and anastomosis with uterine repair was the most common (86.8%) surgical procedure performed. Complication and mortality rates were 47.1% and 10.3% respectively. According to multivariate logistic regression analysis, gestational age at termination of pregnancy, delayed presentation, delayed surgical treatment and presence of complications were significantly associated with mortality (P<0.001). The overall median length of hospital stay (LOS) was 18 days (1day to 128 days ). Patients who developed complications stayed longer in the hospital, and this was statistically significant (P=0.012). Bowel perforation following illegally induced abortion is still rampant in our environment and constitutes significantly to high maternal morbidity and mortality. Early recognition of the diagnosis, aggressive resuscitation and early institution of surgical management is of paramount importance if morbidity and mortality associated with bowel perforation are to be avoided

Modeling relaxation and jamming in granular media

We introduce a stochastic microscopic model to investigate the jamming and reorganization of grains induced by an object moving through a granular medium. The model reproduces the experimentally observed periodic sawtooth fluctuations in the jamming force and predicts the period and the power spectrum in terms of the controllable physical parameters. It also predicts that the avalanche sizes, defined as the number of displaced grains during a single advance of the object, follow a power-law, $P(s)\sim s^{-\tau}$, where the exponent is independent of the physical parameters

Noise kernel for a quantum field in Schwarzschild spacetime under the Gaussian approximation

A method is given to compute an approximation to the noise kernel, defined as the symmetrized connected 2-point function of the stress tensor, for the conformally invariant scalar field in any spacetime conformal to an ultra-static spacetime for the case in which the field is in a thermal state at an arbitrary temperature. The most useful applications of the method are flat space where the approximation is exact and Schwarzschild spacetime where the approximation is better than it is in most other spacetimes. The two points are assumed to be separated in a timelike or spacelike direction. The method involves the use of a Gaussian approximation which is of the same type as that used by Page to compute an approximate form of the stress tensor for this field in Schwarzschild spacetime. All components of the noise kernel have been computed exactly for hot flat space and one component is explicitly displayed. Several components have also been computed for Schwarzschild spacetime and again one component is explicitly displayed.Comment: 34 pages, no figures. Substantial revisions in Secs. I, IV, and V; minor revisions elsewhere; new results include computation of the exact noise kernel for hot flat space and an approximate computation of the noise kernel for a thermal state at an arbitrary temperature in Schwarzschild spacetime when the points are split in the time directio

A Spatial Perspective on the Phenological Distribution of the Spring Woodland Caterpillar Peak

A classic system for studying trophic mismatch focuses on the timing of the spring caterpillar peak in relation to the breeding time and productivity of woodland passerine birds. Most work has been conducted in single-site oak woodlands, and little is known about how insights generalize to other woodland types or across space. Here we present the results of a 3-year study on the species composition and temporal distribution of the spring caterpillar peak on different tree taxa across 40 woodland sites spanning 2° of latitude in Scotland. We used molecular barcoding to identify 62 caterpillar species, with winter moth (Operophtera brumata) being the most abundant, comprising one-third of the sample. Oak (Quercus sp.) and willow (Salix sp.) hosted significantly higher caterpillar abundances than other tree taxa, with winter moth exhibiting similar trends and invariantly proportionate across tree taxa. Caterpillar peak phenology was broadly similar between tree taxa. While latitude had little effect, increasing elevation increased the height of the caterpillar peak and retarded timing by 3.7 days per 100 m. These findings extend our understanding of how mismatch may play out spatially, with caterpillar peak date varying with elevation and tree taxa varying in the caterpillar resource that they host

Detecting photon-photon scattering in vacuum at exawatt lasers

In a recent paper, we have shown that the QED nonlinear corrections imply a phase correction to the linear evolution of crossing electromagnetic waves in vacuum. Here, we provide a more complete analysis, including a full numerical solution of the QED nonlinear wave equations for short-distance propagation in a symmetric configuration. The excellent agreement of such a solution with the result that we obtain using our perturbatively-motivated Variational Approach is then used to justify an analytical approximation that can be applied in a more general case. This allows us to find the most promising configuration for the search of photon-photon scattering in optics experiments. In particular, we show that our previous requirement of phase coherence between the two crossing beams can be released. We then propose a very simple experiment that can be performed at future exawatt laser facilities, such as ELI, by bombarding a low power laser beam with the exawatt bump.Comment: 8 pages, 6 figure