APEX: A Prime EXperiment at Jefferson Lab

APEX is an experiment at Thomas Jefferson National Accelerator Facility (JLab) in Virginia, USA, that searches for a new gauge boson ($A^\prime$) with sub-GeV mass and coupling to ordinary matter of $g^\prime \sim (10^{-6} - 10^{-2}) e$. Electrons impinge upon a fixed target of high-Z material. An $A^\prime$ is produced via a process analogous to photon bremsstrahlung, decaying to an $e^+ e^-$ pair. A test run was held in July of 2010, covering $m_{A^\prime}$ = 175 to 250 MeV and couplings g^\prime/e \; \textgreater \; 10^{-3}. A full run is approved and will cover $m_{A^\prime} \sim$ 65 to 525 MeV and g^\prime/e \; \textgreater \; 2.3 \times10^{-4}.Comment: Contributed to the 8th Patras Workshop on Axions, WIMPs and WISPs, Chicago, July 18-22, 2012. 4 pages, 4 figure

MODELING RATIOS WITH POTENTIAL ZERO-INFLATION TO ASSESS SOIL NEMATODE COMMUNITY STRUCTURE

The southern root-knot nematode (SRKN) and the weedy perennials, yellow nutsedge (YNS) and purple nutsedge (PNS) are simultaneously-occurring pests in the irrigated agricultural soils of southern New Mexico. Previous research has characterized SRKN, YNS and PNS as a mutually beneficial pest complex and has shown their enhanced population growth and survival when they occur together. In addition, it was shown that the density of nutsedge in a field could be used as a predictor of SRKN juveniles in the soil. In addition to SRKN, which is the most harmful of the plant parasitic nematodes, in southern New Mexico other species or categories of nematodes were identified and counted. Some of them are not as damaging to crop plants as SRKN, and some of them may be essential for soil health. The nematode species could be grouped into categories according to trophic level (what nematodes eat) and herbivore feeding behavior (how herbivore nematodes eat). Then three ratios of counts each were calculated for trophic and feeding behavior categories to investigate the soil nematode community structure. These proportions were modeled as functions of the weed hosts YNS and PNS by generalized linear regression models using the logit link function and three distributions: the Binomial, Zero-Inflated Binomial (ZIB) and Binomial Hurdle (BH). The latter two were used to account for potential high proportions of zeroes in the data. Formulas for the probability mass functions and moments were developed for the ZIB and BH. The SAS NLMIXED procedure was used to fit models for each of three sampling dates (May, July and September) in the two years of an alfalfa field study. General results showed that the Binomial generally provided the best fit, indicating lower zero-inflation than expected, but that ZIB and BH are often comparable. Importance of YNS and PNS predictors varied over sample dates and ratios. Specific results for one selected ratio illustrate the differences in estimated probabilities between Binomial, ZIB and BH distributions as YNS counts increase

Comparison of Skin Biomechanics and Skin Color in Puerto Rican and Non-Puerto Rican Women

Objective: Skin biomechanics are physical properties that protect the body from injury. Little is known about differences in skin biomechanics in racial/ethnic groups and the role of skin color in these differences. The purpose of this study was to determine the relationship between skin biomechanics (viscoelasticity, hydration) and skin color, when controlling for demographic and health-related variables in a sample of Puerto Rican and non-Puerto Rican women. Methods: We performed a secondary analysis of data from 545 women in a longitudinal, observational study of skin injury in Puerto Rico and the United States. Data included measures of skin viscoelasticity, skin hydration, skin color, demographic, and health-related variables. Skin color was measured by spectrophotometry (L* - lightness/darkness, a*- redness/greenness, b* - yellowness/blueness). The sample was 12.5% Puerto Rican, 27.3% non-Puerto Rican Latina, 28.8% Black, 28.6% White, and 2.8% Other. Results: Regression analyses showed that: 1) higher levels of skin viscoelasticity were associated with lower age, higher BMI, and identifying as non-Puerto Rican Latina as compared to Puerto Rican; (all p \u3c .001); and 2) higher levels of hydration were associated with lower L* values, higher health status, lower BMI, and identifying as non-Puerto Rican Latina, White, or Other as compared to Puerto Rican (all p \u3c .05). Conclusion: When adjusting for skin color, Puerto Rican women had lower viscoelasticity and hydration as compared to other groups. Puerto Rican women may be at long-term risk for skin alterations, including pressure injury, as they age or become chronically ill

Engineering The Unicellular Alga Phaeodactylum tricornutum For High-Value Plant Triterpenoid Production

Plant triterpenoids constitute a diverse class of organic compounds that play a major role in development, plant defense and environmental interaction. Several triterpenes have demonstrated potential as pharmaceuticals. One example is betulin, which has shown promise as a pharmaceutical precursor for the treatment of certain cancers and HIV. Major challenges for triterpenoid commercialization include their low production levels and their cost‐effective purification from the complex mixtures present in their natural hosts. Therefore, attempts to produce these compounds in industrially relevant microbial systems such as bacteria and yeasts have attracted great interest. Here we report the production of the triterpenes betulin and its precursor lupeol in the photosynthetic diatom Phaeodactylum tricornutum, a unicellular eukaryotic alga. This was achieved by introducing three plant enzymes in the microalga: a Lotus japonicus oxidosqualene cyclase and a Medicago truncatula cytochrome P450 along with its native reductase. The introduction of the L. japonicus oxidosqualene cyclase perturbed the mRNA expression levels of the native mevalonate and sterol biosynthesis pathway. The best performing strains were selected and grown in a 550L pilot scale photobioreactor facility. To our knowledge, this is the most extensive pathway engineering undertaken in a diatom and the first time that a sapogenin has been artificially produced in a microalga, demonstrating the feasibility of the photo‐bio‐production of more complex high‐value, metabolites in microalgae

Analysis of seaweeds from South West England as a biorefinery feedstock

Seaweeds contain many varied and commercially valuable components, from individual pigments and metabolites through to whole biomass, and yet they remain an under cultivated and underutilised commodity. Currently, commercial exploitation of seaweeds is predominantly limited to whole biomass consumption or single product extracts for the food industry. The development of a seaweed biorefinery, based around multiple products and services, could provide an important opportunity to exploit new and currently underexplored markets. Here, we assessed the native and invasive seaweeds on the South West coast of the UK to determine their characteristics and potential for exploitation through a biorefinery pipeline, looking at multiple components including pigments, carbohydrates, lipids, proteins and other metabolites.</p

Towards a marine biorefinery through the hydrothermal liquefaction of macroalgae native to the United Kingdom

Hydrothermal liquefaction (HTL) is a promising biomass conversion method that can be incorporated into a biorefinery paradigm for simultaneous production of fuels, aqueous fertilisers and potential remediation of municipal or mariculture effluents. HTL of aquatic crops, such as marine macro- or microalgae, has significant potential for the UK owing to its extensive coastline. As such, macroalgae present a particularly promising feedstock for future UK biofuel production. This study aimed to bridge the gaps between previous accounts of macroalgal HTL by carrying out a more comprehensive screen of a number of species from all three major macroalgae classes, and examining the correlations between biomass biochemical composition and HTL reactivity. HTL was used to process thirteen South West UK macroalgae species from all three major classes (Chlorophyceae, Heterokontophyceae and Rhodophyceae) to produce bio-crude oil, a bio-char, gas and aqueous phase products. Chlorophyceae of the genus Ulva generated the highest bio-crude yields (up to 29.9% for U. lactuca). Aqueous phase phosphate concentrations of up to 236 mg L−1 were observed, obtained from the Rhodophyta, S. chordalis. Across the 13 samples, a correlation between increasing biomass lipids and increasing bio-crude yield was observed, as well as an increase in biomass nitrogen generally contributing to bio-crude nitrogen content. A broader range of macroalgae species has been examined than in any study previously and, by processing using identical conditions across all feedstocks, has enabled a more cohesive assessment of the effects of biochemical composition

Search for a new gauge boson in the A′A' Experiment (APEX)

We present a search at Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling $\alpha'$ to electrons. Such a particle $A'$ can be produced in electron-nucleus fixed-target scattering and then decay to an $e^+e^-$ pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175--250 MeV, found no evidence for an $A'\to e^+e^-$ reaction, and set an upper limit of $\alpha'/\alpha \simeq 10^{-6}$. Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.Comment: 5 pages, 5 figures, references adde

PHI-base update: additions to the pathogen–host interaction database

The pathogen–host interaction database (PHI-base) is a web-accessible database that catalogues experimentally verified pathogenicity, virulence and effector genes from bacterial, fungal and Oomycete pathogens, which infect human, animal, plant, insect, fish and fungal hosts. Plant endophytes are also included. PHI-base is therefore an invaluable resource for the discovery of genes in medically and agronomically important pathogens, which may be potential targets for chemical intervention. The database is freely accessible to both academic and non-academic users. This publication describes recent additions to the database and both current and future applications. The number of fields that characterize PHI-base entries has almost doubled. Important additional fields deal with new experimental methods, strain information, pathogenicity islands and external references that link the database to external resources, for example, gene ontology terms and Locus IDs. Another important addition is the inclusion of anti-infectives and their target genes that makes it possible to predict the compounds, that may interact with newly identified virulence factors. In parallel, the curation process has been improved and now involves several external experts. On the technical side, several new search tools have been provided and the database is also now distributed in XML format. PHI-base is available at: http://www.phi-base.org/