Aquatic Macrophytes of Two Small Northwest Arkansas Reservoirs

Lake Fayetteville and Lake Wedington are small reservoirs of about the same size and age that are located in northwestern Arkansas. We collected macrophytes from eleven transects around each reservoir in the autumn of 1993. Justicia (waterwillow), Typha (cat-tail), Scirpus (bulrush), Potamogeton (pondweed), and Zannichellia (horned pondweed) occur in both reservoirs. Justicia occurs most commonly in both reservoirs. The macrophytes of Lake Wedington are organized in a characteristic zonation pattern with bands from shore toward open water of emergent, floating-leaved, then submersed macrophytes. Macrophyte zonation was not as evident in Lake Fayetteville because of the low occurrence of floating leaved and submersed macrophytes in1993. Early studies of Lake Wedington found that the dominant macrophytes were Cyperus, Echinochloa, Lotus, and Sagittaria, all of which were absent during this study. Potamogeton, Scirpus, and Typha were also found to be dominant during 1952 studies, but occurred in lesser amounts in the current study. Previous studies (1956, 1967, 1977) on Lake Fayetteville stated that Sagittaria and Nelumbo were dominant macrophytes, but we found none in1993. Juncus, Potamogeton, Scirpus, and Typha were common in the early studies but occurred infrequently in our collections. Macrophyte composition in Lake Fayetteville in 1993 was attributable to an herbicide application that occurred in spring, 1992. As for the changes in Lake Wedington, we assume that the Justicia has out-competed those macrophytes that were in the reservoir in1952, or that normal lake ontogeny during the intervening 40 years has altered habitat conditions to now favor Justicia

Incentivising Specific Combinations of Subjects – Does It Make Any Difference to University Access?

A major part of the 2010–15 UK government's education reforms in England was a focus on the curriculum that pupils study from ages 14–16. Most high profile was the introduction of the English Baccalaureate (EBacc) performance measure for schools, incentivising study of “subjects the Russell Group identifies as key for university study” (Gibb, 2011). However, there does not appear to be good quantitative evidence about the importance of studying such a set of subjects, per se. This paper sets out to analyse this question, considering whether otherwise similar young people who study specific sets of subjects (full set for EBacc-eligibility, two or more sciences, foreign languages, applied subjects) to age 16 have different probabilities of entering university, and specifically a high-status university. It compares results from regression modelling and propensity score matching, taking advantage of rich survey data from a recent cohort of young people in England. We find that conditional differences in university entry attributable to subject choice are, at most, small

A note on subject choice at age 14 and socio-economic inequality in access to university

Over the past twenty years governmental efforts to promote social mobility have included widening access to higher education as a major focus. This is in an attempt to give more individuals the opportunity to benefit from the economic returns to a university degree (Walker and Zhu, 2011). Despite this, there remains a significant level of socioeconomic inequality in access to universities (Anders, 2012a; Boliver, 2013; Chowdry et al., 2013). Much of this inequality is explained by, or emerges through, differences in prior attainment at age 16

Aerothermal modeling program, phase 2

The main objectives of the Aerothermal Modeling Program, Phase 2 are: to develop an improved numerical scheme for incorporation in a 3-D combustor flow model; to conduct a benchmark quality experiment to study the interaction of a primary jet with a confined swirling crossflow and to assess current and advanced turbulence and scalar transport models; and to conduct experimental evaluation of the air swirler interaction with fuel injectors, assessments of current two-phase models, and verification the improved spray evaporation/dispersion models

Pseudo-Riemannian geodesic foliations by circles

We investigate under which assumptions an orientable pseudo-Riemannian geodesic foliations by circles is generated by an $S^1$-action. We construct examples showing that, contrary to the Riemannian case, it is not always true. However, we prove that such an action always exists when the foliation does not contain lightlike leaves, i.e. a pseudo-Riemannian Wadsley's Theorem. As an application, we show that every Lorentzian surface all of whose spacelike/timelike geodesics are closed, is finitely covered by $S^1\times \R$. It follows that every Lorentzian surface contains a non-closed geodesic.Comment: 14 page

Weak Localization Thickness Measurements of Si:P Delta-Layers

We report on our results for the characterization of Si:P delta-layers grown by low temperature molecular beam epitaxy. Our data shows that the effective thickness of a delta-layer can be obtained through a weak localization analysis of electrical transport measurements performed in perpendicular and parallel magnetic fields. An estimate of the diffusivity of phosphorous in silicon is obtained by applying this method to several samples annealed at 850 Celsius for intervals of zero to 15 minutes. With further refinements, this may prove to be the most precise method of measuring delta-layer widths developed to date, including that of Secondary Ion Mass Spectrometry analysis

Ovogénesis y formación de la puesta de los peces invasores Pterois miles y Pterois volitans

The Indo-Pacific lionfish, Pterois miles and P. volitans, have recently invaded the U.S. east coast and the Caribbean and pose a significant threat to native reef fish communities. Few studies have documented reproduction in pteroines from the Indo-Pacific. This study provides a description of oogenesis and spawn formation in P. miles and P. volitans collected from offshore waters of North Carolina, U.S.A and the Bahamas. Using histological and laboratory observations, we found no differences in reproductive biology between P. miles and P. volitans. These lionfish spawn buoyant eggs that are encased in a hollow mass of mucus produced by specialized secretory cells of the ovarian wall complex. Oocytes develop on highly vascularized peduncles with all oocyte stages present in the ovary of spawning females and the most mature oocytes placed terminally, near the ovarian lumen. Given these ovarian characteristics, these lionfish are asynchronous, indeterminate batch spawners and are thus capable of sustained reproduction throughout the year when conditions are suitable. This mode of reproduction could have contributed to the recent and rapid establishment of these lionfish in the northwestern Atlantic and Caribbean.Los peces Indo-Pacíficos, Pterois miles y P. volitans, han invadido recientemente la costa este de los Estados Unidos y el Caribe y representan una significativa amenaza a las comunidades nativas de peces coralinos. Unos pocos estudios han documentado la reproducción en peces de la subfamilia Pteroinae del Indo-Pacífico. Este estudio presenta la descripción de la ovogénesis y la formación de puesta en P. miles y P. volitans recolectados desde aguas a mar abierto de Carolina del Norte, U.S.A, y las Bahamas. Mediante el uso de observaciones histológicas y de laboratorio, encontramos que no había diferencias en la biología reproductiva entre P. miles y P. volitans. Estas especies desovan huevos flotantes que están encerrados en una masa hueca de moco producida por células secretoras especializadas del complejo de la pared del ovario. Los ovocitos se desarrollan en pedúnculos altamente especializados, estando todos los estadios de los ovocitos presentes en el ovario de las hembras en puesta, y los ovocitos más maduros se localizan en la zona terminal, cerca del lumen del ovario. Dadas estas características del ovario, estas especies son asincrónicas, ponedores secuenciales indeterminados y son, por tanto, capaces de tener una reproducción sostenida a lo largo del año cuando las condiciones son adecuadas. Este modo de reproducción podría haber contribuido al rápido reciente establecimiento de estas especies en el noroeste del Atlántico y Caribe

Elastic electron scattering from 3-hydroxytetrahydrofuran: experimental and theoretical studies

We report the results of measurements and calculations for elastic electron scattering from 3-hydroxytetrahydrofuran (C4H8O2). The measurements are performed with a crossed electron-target beam apparatus and the absolute cross-sections are determined using the relative flow technique. The calculations are carried out using the Schwinger multichannel method in the static-exchange plus polarization (SEP) approximation. A set of angular differential cross-sections (DCS) is provided at five incident energies (6.5, 8, 10, 15 and 20 eV) over an angular range of 20–130°, and the energy dependence of the elastic DCS at a scattering angle of 120° is also presented. Integral elastic and elastic momentum transfer cross-sections have also been derived and calculated. The results are compared with those of recent measurements and calculations for the structurally similar molecule tetrahydrofuran (C4H8O)

Effects of intracerebral neurotrophic factor application on motor symptoms in Parkinson's disease: a systematic review and meta-analysis

Introduction: Neurotrophic factors (NTFs) have been evaluated for neuroprotective effects in Parkinson's disease (PD). However, clinical trials examining the efficacy of intracerebral administration of NTFs on motor symptoms in PD have produced mixed results, and are thus inconclusive. The objective of this systematic review and meta-analysis was to determine the effects of intracerebral NTF application on motor symptoms in people with PD. Methods: We searched PubMed, MEDLINE, EMBASE, and Cochrane from inception through to March 31 2016 for open-label trials and randomized controlled trials (RCTs) which intracerebrally administered NTFs to PD patients, and which performed motor examination of Unified Parkinson's Disease Rating Scale. Results: Eight studies with a total of 223 participants were included. Fixed effects analysis revealed that NTF treatment did not significantly reduce motor symptoms in PD patients compared to placebo controls (P = 0.98). Combining open-label and RCT data, both treatment with NTFs (P < 0.001) and treatment with placebo (P < 0.05) significantly improved motor function in PD patients when compared to predicted symptoms in untreated PD controls. Finally, random effects analysis revealed that NTF-treated PD patients were not significantly likely to improve following intracerebral NTF administration (P = 0.25). Conclusion: In conclusion, intracerebral NTF administration does not improve motor symptoms in PD patients, when compared to placebo-treated controls. These findings may guide therapeutic decisions and inform future research on NTFs and their application in PD