Advanced high-temperature batteries

The promise of very high specific energy and power was not yet achieved for practical battery systems. Some recent approaches are discussed for new approaches to achieving high performance for lithium/DeS2 cells and sodium/metal chloride cells. The main problems for the development of successful LiAl/FeS2 cells were the instability of the FeS2 electrode, which has resulted in rapidly declining capacity, the lack of an internal mechanism for accommodating overcharge of a cell, thus requiring the use of external charge control on each individual cell, and the lack of a suitable current collector for the positive electrode other than expensive molybdenum sheet material. Much progress was made in solving the first two problems. Reduction of the operating temperatures to 400 C by a change in electrolyte composition has increased the expected life to 1000 cycles. Also, a lithium shuttle mechanism was demonstrated for selected electrode compositions that permits sufficient overcharge tolerance to adjust for the normally expected cell-to-cell deviation in coulombic efficiency. Sodium/sulfur batteries and sodium/metal chloride batteries have demonstrated good reliability and long cycle life. For applications where very high power is desired, new electrolyte coinfigurations would be required. Design work was carried out for the sodium/metal chloride battery that demonstrates the feasibility of achieving high specific energy and high power for large battery cells having thin-walled high-surface area electrolytes

Physician\u27s View of Whiplash Injuries of the Neck

Whiplash injuries of the neck as the result of automobile accidents have attracted increased attention in recent years from both the medical and legal professions. The incidence of such injuries has risen steadily, paralleling the increase in the number of automobiles and in the number of accidents on our highways. Unfortunately, effective safety measures or changes in automobile design that might prevent or minimize these injuries have not yet been introduced. Because most whiplash injuries involve compensation and many entail litigation, the correct management of such cases both medically and legally is of considerable economic importance

Physician\u27s View of Whiplash Injuries of the Neck

Whiplash injuries of the neck as the result of automobile accidents have attracted increased attention in recent years from both the medical and legal professions. The incidence of such injuries has risen steadily, paralleling the increase in the number of automobiles and in the number of accidents on our highways. Unfortunately, effective safety measures or changes in automobile design that might prevent or minimize these injuries have not yet been introduced. Because most whiplash injuries involve compensation and many entail litigation, the correct management of such cases both medically and legally is of considerable economic importance

Problems with Characterizing the Protostome-Deuterostome Ancestor

Since Darwin’s time, the origins and relationships of the bilaterian animals have remained unsolved problems in historical biology (Conway Morris 2000). One of the central difficulties is characterizing the common ancestor of the protostomes and deuterostomes. We argue that an unresolved conceptual puzzle has plagued the many attempts to describe this Urbilaterian, or, in Erwin and Davidson’s (2002) terminology, the protostome-deuterostome ancestor (PDA). Any organism sophisticated enough to be a realistic candidate for the PDA, with such characters as an anterior-posterior axis, gut, and sensory organs, must itself have been constructed by a developmental process, or by what we term an ontogenetic network (Ross and Nelson 2002). But the more biologically plausible the PDA becomes, as a functioning organism within a population of other such organisms, the more it will tend to “pull” (in its characters) towards one or another of the known bilaterian groups. As this happens, and the organism loses its descriptive generality, it will cease to be a good candidate Urbilaterian

Extended Water Quality Monitoring of the Lincoln Lake Watershed

For seven years, the Lincoln Lake (Moores Creek and Beatty Branch) watershed was monitored for improvements in water quality resulting from agricultural best management practices (BMP) implemented to reduce nutrient transport. During the first three years of monitoring (1991 to 1994), nitrogen transport declined significantly (Edwards et al., 1994, 1996, and 1997) under both base and storm flow conditions. This decline in nitrogen transport was again observed in the three-year period following 1994 (Vendrell et al. 1998). This monitoring effort has demonstrated that water quality bas improved in the Lincoln Lake watershed. However, since the nitrogen transport continued to decline and there was some indication that phosphorus may begin to decline, monitoring was extended for another year (1998)

Research Mentoring and Scientist Identity: Insights from Undergraduates and their Mentors

Background Mentored research apprenticeships are a common feature of academic outreach programs that aim to promote diversity in science fields. The current study tests for links between three forms of mentoring (instrumental, socioemotional, and negative) and the degree to which undergraduates psychologically identify with science. Participants were 66 undergraduate-mentor dyads who worked together in a research apprenticeship. The undergraduate sample was predominantly composed of women, first-generation college students, and members of ethnic groups that are historically underrepresented in science. Results Findings illustrated that undergraduates who reported receiving more instrumental and socioemotional mentoring were higher in scientist identity. Further, mentors who reported engaging in higher levels of negative mentoring had undergraduates with lower scientist identity. Qualitative data from undergraduates’ mentors provided deeper insight into their motivation to become mentors and how they reason about conflict in their mentoring relationships. Conclusions Discussion highlights theoretical implications and details several methodological recommendations

Biological Consequences of Tightly Bent DNA: The Other Life of a Macromolecular Celebrity

The mechanical properties of DNA play a critical role in many biological functions. For example, DNA packing in viruses involves confining the viral genome in a volume (the viral capsid) with dimensions that are comparable to the DNA persistence length. Similarly, eukaryotic DNA is packed in DNA-protein complexes (nucleosomes) in which DNA is tightly bent around protein spools. DNA is also tightly bent by many proteins that regulate transcription, resulting in a variation in gene expression that is amenable to quantitative analysis. In these cases, DNA loops are formed with lengths that are comparable to or smaller than the DNA persistence length. The aim of this review is to describe the physical forces associated with tightly bent DNA in all of these settings and to explore the biological consequences of such bending, as increasingly accessible by single-molecule techniques.Comment: 24 pages, 9 figure

A Generalized Theory of Semiflexible Polymers

NA bending on length scales shorter than a persistence length plays an integral role in the translation of genetic information from DNA to cellular function. Quantitative experimental studies of these biological systems have led to a renewed interest in the polymer mechanics relevant for describing the conformational free energy of DNA bending induced by protein-DNA complexes. Recent experimental results from DNA cyclization studies have cast doubt on the applicability of the canonical semiflexible polymer theory, the wormlike chain (WLC) model, to DNA bending on biologically relevant length scales. This paper develops a theory of the chain statistics of a class of generalized semiflexible polymer models. Our focus is on the theoretical development of these models and the calculation of experimental observables. To illustrate our methods, we focus on a specific, illustrative model of DNA bending. We show that the WLC model generically describes the long-length-scale chain statistics of semiflexible polymers, as predicted by renormalization group arguments. In particular, we show that either the WLC or our present model adequately describes force-extension, solution scattering, and long-contour-length cyclization experiments, regardless of the details of DNA bend elasticity. In contrast, experiments sensitive to short-length-scale chain behavior can in principle reveal dramatic departures from the linear elastic behavior assumed in the WLC model. We demonstrate this explicitly by showing that our toy model can reproduce the anomalously large short-contour-length cyclization factors recently measured by Cloutier and Widom. Finally, we discuss the applicability of these models to DNA chain statistics in the context of future experiments

Recoiling black holes: prospects for detection and implications of spin alignment

Supermassive black hole (BH) mergers produce powerful gravitational wave (GW) emission. Asymmetry in this emission imparts a recoil kick to the merged BH, which can eject the BH from its host galaxy altogether. Recoiling BHs could be observed as offset active galactic nuclei (AGN). Several candidates have been identified, but systematic searches have been hampered by large uncertainties regarding their observability. By extracting merging BHs and host galaxy properties from the Illustris cosmological simulations, we have developed a comprehensive model for recoiling AGN. Here, for the first time, we model the effects of BH spin alignment and recoil dynamics based on the gas-richness of host galaxies. We predict that if BH spins are not highly aligned, seeing-limited observations could resolve offset AGN, making them promising targets for all-sky surveys. For randomly-oriented spins, less than about 10 spatially-offset AGN may be detectable in HST-COSMOS, and > 10^3 could be found with Pan-STARRS, LSST, Euclid, and WFIRST. Nearly a thousand velocity-offset AGN are predicted within the SDSS footprint; the rarity of large broad-line offsets among SDSS quasars is likely due in part to selection effects but suggests that spin alignment plays a role in suppressing recoils. Nonetheless, in our most physically motivated model where alignment occurs only in gas-rich mergers, hundreds of offset AGN should be found in all-sky surveys. Our findings strongly motivate a dedicated search for recoiling AGN.Comment: 30 pages, 19 figures. Accepted to MNRAS after minor revision