On Upper Bounds for Toroidal Mosaic Numbers

In this paper, we work to construct mosaic representations of knots on the torus, rather than in the plane. This consists of a particular choice of the ambient group, as well as different definitions of contiguous and suitably connected. We present conditions under which mosaic numbers might decrease by this projection, and present a tool to measure this reduction. We show that the order of edge identification in construction of the torus sometimes yields different resultant knots from a given mosaic when reversed. Additionally, in the Appendix we give the catalog of all 2 by 2 torus mosaics.Comment: 10 pages, 111 figure

Determination of biomembrane bending moduli in fully atomistic simulations.

The bilayer bending modulus (Kc) is one of the most important physical constants characterizing lipid membranes, but precisely measuring it is a challenge, both experimentally and computationally. Experimental measurements on chemically identical bilayers often differ depending upon the techniques employed, and robust simulation results have previously been limited to coarse-grained models (at varying levels of resolution). This Communication demonstrates the extraction of Kc from fully atomistic molecular dynamics simulations for three different single-component lipid bilayers (DPPC, DOPC, and DOPE). The results agree quantitatively with experiments that measure thermal shape fluctuations in giant unilamellar vesicles. Lipid tilt, twist, and compression moduli are also reported

Efficient protein depletion by genetically controlled deprotection of a dormant N-degron

Methods that allow for the manipulation of genes or their products have been highly fruitful for biomedical research. Here, we describe a method that allows the control of protein abundance by a genetically encoded regulatory system. We developed a dormant N-degron that can be attached to the N-terminus of a protein of interest. Upon expression of a site-specific protease, the dormant N-degron becomes deprotected. The N-degron then targets itself and the attached protein for rapid proteasomal degradation through the N-end rule pathway. We use an optimized tobacco etch virus (TEV) protease variant combined with selective target binding to achieve complete and rapid deprotection of the N-degron-tagged proteins. This method, termed TEV protease induced protein inactivation (TIPI) of TIPI-degron (TDeg) modified target proteins is fast, reversible, and applicable to a broad range of proteins. TIPI of yeast proteins essential for vegetative growth causes phenotypes that are close to deletion mutants. The features of the TIPI system make it a versatile tool to study protein function in eukaryotes and to create new modules for synthetic or systems biology

Renormalization of minimally doubled fermions

We investigate the renormalization properties of minimally doubled fermions, at one loop in perturbation theory. Our study is based on the two particular realizations of Borici-Creutz and Karsten-Wilczek. A common feature of both formulations is the breaking of hyper-cubic symmetry, which requires that the lattice actions are supplemented by suitable counterterms. We show that three counterterms are required in each case and determine their coefficients to one loop in perturbation theory. For both actions we compute the vacuum polarization of the gluon. It is shown that no power divergences appear and that all contributions which arise from the breaking of Lorentz symmetry are cancelled by the counterterms. We also derive the conserved vector and axial-vector currents for Karsten-Wilczek fermions. Like in the case of the previously studied Borici-Creutz action, one obtains simple expressions, involving only nearest-neighbour sites. We suggest methods how to fix the coefficients of the counterterms non-perturbatively and discuss the implications of our findings for practical simulations.Comment: 23 pages, 1 figur

Gender differences in climate change perception and adaptation strategies: A case study on three provinces in Vietnam’s Mekong River Delta

This brief summarizes the findings of a project output for the Policy Information and Response Platform on Climate Change and Rice in ASEAN and its Member Countries (PIRCCA), being implemented by the International Rice Research Institute (IRRI). The report focuses on the results of the survey conducted in the first half of 2015 on climate change perception and adaptation strategies of male and female farmers in three selected provinces across the Mekong River Delta (MRD) region in Vietnam: An Giang, Bac Lieu, and Tra Vihn. The survey gathered information on current climate change perceptions and adaptation strategies and gaps between the identified male and female respondents

Hybridization and speciation in angiosperms: a role for pollinator shifts?

The majority of convincingly documented cases of hybridization in angiosperms has involved genetic introgression between the parental species or formation of a hybrid species with increased ploidy; however, homoploid (diploid) hybridization may be just as common. Recent studies, including one in BMC Evolutionary Biology, show that pollinator shifts can play a role in both mechanisms of hybrid speciation

Functional Independence and Health-related Functional Status Following Spinal Cord Injury:A Prospective Study of the Association with Physical Capacity

Objective: To determine changes in functional independence following spinal cord injury and to evaluate the association between functional independence and physical capacity. Design: Multi-centre prospective cohort study.Subjects: Patients with spinal cord injury admitted for initial rehabilitation.Methods: The motor Functional Independence Measure (FIMmotor) was determined at the start of rehabilitation (n = 176), 3 months later (n = 124), at discharge (n = 160) and one year after discharge from inpatient rehabilitation (n = 133). One year after discharge, physical and social dimensions of health-related functional status (Sickness Impact Profile 68; SIP68) were determined. On each occasion, physical capacity was established by measuring arm muscle strength, peak power output and peak oxygen uptake.Results: Multi-level random coefficient analyses revealed that FIMmotor improved during inpatient rehabilitation, but stabilized thereafter. Changes in FIMmotor were associated with peak power output. Multiple regression models showed that FIMmotor and peak power output at discharge were associated with FIMmotor one year after discharge (R-2 = 0.85), and that peak power output at discharge was associated with the social dimension of the SIP68 (R-2 = 0.18) one year after discharge.Conclusion: Functional independence improves during inpatient rehabilitation, and functional independence is positively associated with peak power output

Apoptosis at Inflection Point in Liquid Culture of Budding Yeasts

Budding yeasts are highly suitable for aging studies, because the number of bud scars (stage) proportionally correlates with age. Its maximum stages are known to reach at 20–30 stages on an isolated agar medium. However, their stage dynamics in a liquid culture is virtually unknown. We investigate the population dynamics by counting scars in each cell. Here one cell division produces one new cell and one bud scar. This simple rule leads to a conservation law: “The total number of bud scars is equal to the total number of cells.” We find a large discrepancy: extremely fewer cells with over 5 scars than expected. Almost all cells with 6 or more scars disappear within a short period of time in the late log phase (corresponds to the inflection point). This discrepancy is confirmed directly by the microscopic observations of broken cells. This finding implies apoptosis in older cells (6 scars or more)

Low-Level Exposure to Multiple Chemicals: Reason for Human Health Concerns?

BACKGROUND: A key question in the risk assessment of exposures to multiple chemicals is whether mixture effects may occur when chemicals are combined at low doses which individually do not induce observable effects. However, a systematic evaluation of experimental studies addressing this issue is missing. OBJECTIVES: With this contribution, we wish to bridge this gap by providing a systematic assessment of published studies against well-defined quality criteria. RESULTS: On reviewing the low-dose mixture literature, we found good evidence demonstrating significant mixture effects with combinations of chemicals well below their individual no observable adverse effect levels (NOAELs), both with mixtures composed of similarly and dissimilarly acting agents. CONCLUSIONS: The widely held view that mixtures of dissimilarly acting chemicals are "safe" at levels below NOAELs is not supported by empirical evidence. We show that this view is also based on the erroneous assumption that NOAELs can be equated with zero-effect levels. Thus, on the basis of published evidence, it is difficult to rule out the possibility of mixture effects from lowdose multiple exposures

Interaction of the Onset of Spring and Elevated Atmospheric CO(2) on Ragweed (Ambrosia artemisiifolia L.) Pollen Production

Increasing atmospheric carbon dioxide is responsible for climate changes that are having widespread effects on biological systems. One of the clearest changes is earlier onset of spring and lengthening of the growing season. We designed the present study to examine the interactive effects of timing of dormancy release of seeds with low and high atmospheric CO(2) on biomass, reproduction, and phenology in ragweed plants (Ambrosia artemisiifolia L.), which produce highly allergenic pollen. We released ragweed seeds from dormancy at three 15-day intervals and grew plants in climate-controlled glasshouses at either ambient or 700-ppm CO(2) concentrations, placing open-top bags over inflorescences to capture pollen. Measurements of plant height and weight; inflorescence number, weight, and length; and days to anthesis and anthesis date were made on each plant, and whole-plant pollen productivity was estimated from an allometric-based model. Timing and CO(2) interacted to influence pollen production. At ambient CO(2) levels, the earlier cohort acquired a greater biomass, a higher average weight per inflorescence, and a larger number of inflorescences; flowered earlier; and had 54.8% greater pollen production than did the latest cohort. At high CO(2) levels, plants showed greater biomass and reproductive effort compared with those in ambient CO(2) but only for later cohorts. In the early cohort, pollen production was similar under ambient and high CO(2), but in the middle and late cohorts, high CO(2) increased pollen production by 32% and 55%, respectively, compared with ambient CO(2) levels. Overall, ragweed pollen production can be expected to increase significantly under predicted future climate conditions