Strong coprimality and strong irreducibility of Alexander polynomials

A polynomial f(t) with rational coefficients is strongly irreducible if f(t^k) is irreducible for all positive integers k. Likewise, two polynomials f and g are strongly coprime if f(t^k) and g(t^l) are relatively prime for all positive integers k and l. We provide some sufficient conditions for strong irreducibility and prove that the Alexander polynomials of twist knots are pairwise strongly coprime and that most of them are strongly irreducible. We apply these results to describe the structure of the subgroup of the rational knot concordance group generated by the twist knots and to provide an explicit set of knots which represent linearly independent elements deep in the solvable filtration of the knot concordance group.Comment: 16 pages, 6 figure

Estimating marginal cohort working life expectancies from sequential cross-sectional survey data

This article applies recently developed health expectancy methodologies to estimate the average duration of future work life in different states of work ability. Data on working capacity obtained from sequential cross-sectional samples of the cohort population were available from Finnish surveys conducted among active municipal employees. We used these data to estimate cohort marginal probabilities and expected occupancy times in the work ability states. One finding is that the proportion of workers with excellent or good work ability decreased monotonically with advancing age for both genders, but men were prone to have worse work ability and a shorter work career than women. Transition from poor to good or excellent work ability state was estimated to increase working life expectancy of a 45-year-old person by four years for both genders. This study indicates that the work ability of aging Finnish workers deteriorates prematurely, leading to serious socio-economic consequences. Thus it is important to examine the development of work ability already at an early age when it is still possible to intervene in the process

The Composition of the Cell Envelope Affects Conjugation in Bacillus subtilis

Conjugation in bacteria is the contact-dependent transfer of DNA from one cell to another via donor-encoded conjugation machinery. It is a major type of horizontal gene transfer between bacteria. Conjugation of the integrative and conjugative element ICEBs1 into Bacillus subtilis is affected by the composition of phospholipids in the cell membranes of the donor and recipient. We found that reduction (or elimination) of lysyl-phosphatidylglycerol caused by loss of mprF caused a decrease in conjugation efficiency. Conversely, alterations that caused an increase in lysyl-phosphatidylglycerol, including loss of ugtP or overproduction of mprF, caused an increase in conjugation efficiency. In addition, we found that mutations that alter production of other phospholipids, e.g., loss of clsA and yfnI, also affected conjugation, apparently without substantively altering levels of lysyl-phosphatidylglycerol, indicating that there are multiple pathways by which changes to the cell envelope affect conjugation. We found that the contribution of mprF to conjugation was affected by the chemical environment. Wild-type cells were generally more responsive to addition of anions that enhanced conjugation, whereas mprF mutant cells were more sensitive to combinations of anions that inhibited conjugation at pH 7. Our results indicate that mprF and lysyl-phosphatidylglycerol allow cells to maintain relatively consistent conjugation efficiencies under a variety of ionic conditions. IMPORTANCE Horizontal gene transfer is a driving force in microbial evolution, enabling cells that receive DNA to acquire new genes and phenotypes. Conjugation, the contact-dependent transfer of DNA from a donor to a recipient by a donor-encoded secretion machine, is a prevalent type of horizontal gene transfer. Although critically important, it is not well understood how the recipient influences the success of conjugation. We found that the composition of phospholipids in the membranes of donors and recipients influences the success of transfer of the integrative and conjugative element ICEBs1 in Bacillus subtilis. Specifically, the presence of lysyl-phosphatidylglycerol enables relatively constant conjugation efficiencies in a range of diverse chemical environments.National Institutes of Health (U.S.

Differential regulation of bladder pain and voiding function by sensory afferent populations revealed by selective optogenetic activation

Bladder-innervating primary sensory neurons mediate reflex-driven bladder function under normal conditions, and contribute to debilitating bladder pain and/or overactivity in pathological states. The goal of this study was to examine the respective roles of defined subtypes of afferent neurons in bladder sensation and function in vivo via direct optogenetic activation. To accomplish this goal, we generated transgenic lines that express a Channelrhodopsin-2-eYFP fusion protein (ChR2-eYFP) in two distinct populations of sensory neurons: TRPV1-lineage neurons (Trpv1Cre;Ai32, the majority of nociceptors) and Nav1.8+ neurons (Scn10aCre;Ai32, nociceptors and some mechanosensitive fibers). In spinal cord, eYFP+ fibers in Trpv1Cre;Ai32 mice were observed predominantly in dorsal horn (DH) laminae I-II, while in Scn10aCre;Ai32 mice they extended throughout the DH, including a dense projection to lamina X. Fiber density correlated with number of retrogradely-labeled eYFP+ dorsal root ganglion neurons (82.2% Scn10aCre;Ai32 vs. 62% Trpv1Cre;Ai32) and degree of DH excitatory synaptic transmission. Photostimulation of peripheral afferent terminals significantly increased visceromotor responses to noxious bladder distension (30–50 mmHg) in both transgenic lines, and to non-noxious distension (20 mmHg) in Scn10aCre;Ai32 mice. Depolarization of ChR2+ afferents in Scn10aCre;Ai32 mice produced low- and high-amplitude bladder contractions respectively in 53% and 27% of stimulation trials, and frequency of high-amplitude contractions increased to 60% after engagement of low threshold (LT) mechanoreceptors by bladder filling. In Trpv1Cre;Ai32 mice, low-amplitude contractions occurred in 27% of trials before bladder filling, which was pre-requisite for light-evoked high-amplitude contractions (observed in 53.3% of trials). Potential explanations for these observations include physiological differences in the thresholds of stimulated fibers and their connectivity to spinal circuits

Influence of classical resonances on chaotic tunnelling

Dynamical tunnelling between symmetry-related stable modes is studied in the periodically driven pendulum. We present strong evidence that the tunnelling process is governed by nonlinear resonances that manifest within the regular phase-space islands on which the stable modes are localized. By means of a quantitative numerical study of the corresponding Floquet problem, we identify the trace of such resonances not only in the level splittings between near-degenerate quantum states, where they lead to prominent plateau structures, but also in overlap matrix elements of the Floquet eigenstates, which reveal characteristic sequences of avoided crossings in the Floquet spectrum. The semiclassical theory of resonance-assisted tunnelling yields good overall agreement with the quantum-tunnelling rates, and indicates that partial barriers within the chaos might play a prominent role

113th Congress

This report provides a snapshot of the forms and origins of measures that, according to the Legislative Information System of the U.S. Congress, received action on the House floor in the 113th Congress (2013-2014) and the parliamentary procedures used to bring them up for initial House consideration

"Sense of" Resolutions and Provisions

This report discusses specific kinds of resolutions by which Congress may formally express opinions about subjects of current national interest through freestanding simple or concurrent resolutions (called generically "sense of the House," "sense of the Senate," or "sense of the Congress" resolutions). These opinions expressing the views of one or both chambers may be included in other legislation upon introduction or subsequently added by amendment. This report identifies the various forms these expressions may take and the procedures governing such actions

Invoking Cloture in the Senate

This report discuses cloture, which is is the only procedure by which the Senate can vote to set an end to a debate without also rejecting the bill, amendment, conference report, motion, or other matter it has been debating. A Senator can make a nondebatable motion to table an amendment, and if a majority of the Senate votes for that motion, the effect is to reject the amendment. Thus, the motion to table cannot be used to conclude a debate when Senators still wish to speak and to enable the Senate to vote for the proposal it is considering. Only the cloture provisions of Rule XXII achieve this purpose