Accurate molecular energies by extrapolation of atomic energies using an analytic quantum mechanical model

Using a new analytic quantum mechanical method based on Slater's Xalpha method, we show that a fairly accurate estimate of the total energy of a molecule can be obtained from the exact energies of its constituent atoms. The mean absolute error in the total energies thus determined for the G2 set of 56 molecules is about 16 kcal/mol, comparable to or better than some popular pure and hybrid density functional models.Comment: 5 pages, REVTE

[Review of] How to Slowly Kill Yourself and Others in America: Essays by Kiese Laymon

Social scientists will most likely categorize writer Kiese Laymon\u27s collection of essays as a literary intervention into masculinity studies in our current era: marked by the (seeming) paradox of black presidency and celebrity on the one hand, and the entrenchment of police power over black boys and men on the other. Scholars of history and literature might situate Laymon in political and literary traditions stretching from tum-of-the-twentieth century race men to the work of feminists of color in our time, noting his acknowledgements to Ralph Ellison, James Baldwin, Octavia Butler and Toni Morrison (12).1 With its Mississippi setting and sensibility, American Studies scholars will likely soon cite it, particularly the essay Hip-Hop Stole My Southern Black Boy, as an example of the New Southern Studies, which places the Black South and regional identity at the center of an analysis of national economic, political, creative, and intellectual narratives.2 How to Slowly Kill Yourselves and Others in America will surely teach brilliantly in classrooms in all of these fields

Climate Change, One Health and Mercury

Climate change is occurring on both regional and global scales. The use and global distribution of toxic metals is increasing and affecting environmental, animal and human health as a result of air, water and food contamination. Mercury (Hg) in major forms Hg°, Hg2+ and methyl mercury (CH3Hg+) are increasingly available around the globe. Both metal and organic contaminants are impacting the health of all species on the planet. Mercury is an example of a metal that can cause or aggravate a disease state, for example, diabetes. Habitat stewardship is needed to maintain a healthy system, and selecting a keystone species as a bio indicator to monitor changes in contaminant levels over time and space is essential. Mercury can be used to monitor the flow of toxics through the food system. The structural organization of food webs and their sensitivity to disturbances are relevant to predicting the fate of Hg bioavailability related to climate change. Hg needs to be monitored across many ecosystems because it impacts not only human health but also the health of the plants and animals. Monitoring studies are needed to identify changes related to climate change. Increased precipitation and sea level rise will result in greater mercury mobility into the coastal and terrestrial food webs

Single molecule analysis of DNA wrapping and looping by a circular 14mer wheel of the bacteriophage 186 CI repressor

The lytic–lysogenic decision in bacteriophage 186 is governed by the 186 CI repressor protein in a unique way. The 186 CI is proposed to form a wheel-like oligomer that can mediate either wrapped or looped nucleoprotein complexes to provide the cooperative and competitive interactions needed for regulation. Although consistent with structural, biochemical and gene expression data, many aspects of this model are based on inference. Here, we use atomic force microscopy (AFM) to reveal the various predicted wrapped and looped species, and new ones, for CI regulation of lytic and lysogenic transcription. Automated AFM analysis showed CI particles of the predicted dimensions on the DNA, with CI multimerization favoured by DNA binding. Measurement of the length of the wrapped DNA segments indicated that CI may move on the DNA, wrapping or releasing DNA on either side of the wheel. Tethered particle motion experiments were consistent with wrapping and looping of DNA by CI in solution, where in contrast to λ repressor, the looped species were exceptionally stable. The CI regulatory system provides an intriguing comparison with that of nucleosomes, which share the ability to wrap and release similar sized segments of DNA.Haowei Wang, Ian B. Dodd, David D. Dunlap, Keith E. Shearwin, and Laura Finz

A SUBTLE INFRARED EXCESS ASSOCIATED WITH A YOUNG WHITE DWARF IN THE EDINBURGH-CAPE BLUE OBJECT SURVEY

We report the discovery of a subtle infrared excess associated with the young white dwarf EC 05365–4749 at 3.35 and 4.6 μ m. Follow-up spectroscopic observations are consistent with a hydrogen atmosphere white dwarf of effective temperature 22,800 K and log [ g (cm s{sup −2})] = 8.19. High-resolution spectroscopy reveals atmospheric metal pollution with logarithmic abundances of [Mg/H] = −5.36 and [Ca/H] = −5.75, confirming the white dwarf is actively accreting from a metal-rich source with an intriguing abundance pattern. We find that the infrared excess is well modeled by a flat, opaque debris disk, though disk parameters are not well constrained by the small number of infrared excess points. We further demonstrate that relaxing the assumption of a circular dusty debris disk to include elliptical disks expands the widths of acceptable disks, adding an alternative interpretation to the subtle infrared excesses commonly observed around young white dwarfs

Direct Minimization Generating Electronic States with Proper Occupation Numbers

We carry out the direct minimization of the energy functional proposed by Mauri, Galli and Car to derive the correct self-consistent ground state with fractional occupation numbers for a system degenerating at the Fermi level. As a consequence, this approach enables us to determine the electronic structure of metallic systems to a high degree of accuracy without the aid of level broadening of the Fermi-distribution function. The efficiency of the method is illustrated by calculating the ground-state energy of C$_2$ and Si$_2$ molecules and the W(110) surface to which a tungsten adatom is adsorbed.Comment: 4 pages, 4 figure

A quick RNA mini-prep for Neurospora mycelial cultures

Most RNA isolation techniques currently in use have been developed for the processing of large quantities of material. These typically involve multiple phenol extractions (Reinert et al. 1981 Mol. Cell Biol. 1:829-836) or guanadinium isothio-cyanate/cesium chloride gradients (Chirgwin et al. 1979 Biochem 18:5294-5299) and can be both expensive and time consuming. Often, however, needs arise where quantitatively smaller amounts of RNA are needed from many different samples, for example, during time series analyses or when screening transformants for expression of a transformed gene. Under such circumstances, existing techniques are overly time consuming and yield more RNA than is necessary. The availability of a rapid RNA mini-prep is thus desirable. Such a system has been developed for isolating plant RNA (Nagy et al. 1988 Plant Molecular Biology Manual, B4; ed. Gelvin and Schilperoort, Klewer Academic Publishing, pp. 1-29), and we have adapted this procedure for use with Neurospora and, potentially, other filamentous fungi. Below, we describe the use of this procedure with 50 ml mycelial cultures, although we have used in with equal success with 5 ml cultures without scaling down the amounts of any reagents

On the role of a new type of correlated disorder in extended electronic states in the Thue-Morse lattice

A new type of correlated disorder is shown to be responsible for the appearance of extended electronic states in one-dimensional aperiodic systems like the Thue-Morse lattice. Our analysis leads to an understanding of the underlying reason for the extended states in this system, for which only numerical evidence is available in the literature so far. The present work also sheds light on the restrictive conditions under which the extended states are supported by this lattice.Comment: 11 pages, LaTeX V2.09, 1 figure (available on request), to appear in Physical Review Letter