Mass mortality and recolonization of pyura stolonifera (heller) on the south coast of South Africa

A mass mortality of the ascidian Pyura stolonifera (red-bait) was recorded along the Tsitsikamma coast of South Africa in May 1991, following the infection of a large proportion of the population with a white microbialgrowth. At nine subtidal red-bait beds, reductions in percentage cover of red-bait were greatest on the crests of reefs (42 ± 17%:1SD) and lowest on the landward edges (17 ± 8%). The test of P. stolonifera appeared to be the main site of the microbial infection. Scanning electron and epifluorescent microscopy revealed much higher numbers of bacteria on the tests of infected individuals (64.3 ± 5.5 × 106·mm-2) compared to healthy ones (5.1 ± 0.1 × 106·mm-2). Fat, curved rod bacteria and thick chains, which accounted for more than 45% of the bacteria on infected red-bait tests, were absent from the tests of healthy red-bait. Standard characterization techniques, coupled with API tests, showed that the isolates from infected red-bait tests belonged exclusively to thegenus Vibrio, whereas isolates from healthy tests included the genera Vibrio, Pseudomonas, Aeromonas and Flavobacterium/Cytophaga. The mass mortality therefore appeared to be associated with the proliferation of large curved rod bacteria of the genus Vibrio. Recolonization by P. stolonifera into areas naturally denuded of red-bait was significantly faster than for experimental plots cleared of all organisms during the mid 1980s. A mean cover of 33 ± 4% was recorded for P. stolonifera after 38 months following natural mortality, whereas it took 71 months to achieve a comparable recovery of 35 ± 20% in experimental plots. Possible reasons for this difference (viz. substratum, recruitment and predation) are explored

A prospective observational study of outcomes from rehabilitation of elderly patients with moderate to severe cognitive impairment

OBJECTIVES: To evaluate rehabilitation outcomes in patients with moderate to severe cognitive impairment. DESIGN: Prospective observational cohort study. SETTING: Rehabilitation unit for older people. SUBJECTS: A total of 116 patients (70F) mean age (SD) 86.3 (6.4). Group 1: 89 patients with moderate cognitive impairment (Mini-Mental State Examination 11-20); and Group 2: 27 patients with severe cognitive impairment (Mini-Mental State Examination 0-10). INTERVENTION: A personalised rehabilitation plan. MAIN MEASURES: Barthel Activity of Daily Living score on admission and discharge, length of stay and discharge destination. RESULTS: Of 116 patients, 64 (55.2%) showed an improvement in Barthel score. Mini-Mental State Examination was significantly higher in those who improved, 15.4 (SD 3.7) vs.13.2 (SD 5.1): p = 0.01. The mean Barthel score improved in both groups; Group 1 - 14.7 (SD 19.1) vs. Group 2 - 9.3 (SD 16.3): p = 0.17. Of 84 home admissions in Group 1, more patients returning home showed improvements of at least 5 points in the Barthel score compared with nursing/residential home discharges (32/37 - 86.5% vs. 10/28 - 35.7%: p = 0.0001). In Group 2 of 17 home admissions, 6/6 (100%) home discharges showed improvement compared with 3/7 (42.8%) discharges to nursing/residential home (p = 0.07). In Group 1, a discharge home was associated with significantly greater improvement in number of Barthel items than a nursing/residential home discharge (3.27 (SD 2.07) vs. 1.86 (SD 2.32): p = 0.007). A similar non-significant pattern was noted for severe cognitive impairment patients (3.5 (3.06) vs. 1.14 (1.06); p = 0.1). CONCLUSION: Patients with moderate to severe cognitive impairment demonstrated significant improvements in Barthel score and Barthel items showing that such patients can and do improve with rehabilitation.published_or_final_versio

Looking back at superfluid helium

A few years after the discovery of Bose Einstein condensation in several gases, it is interesting to look back at some properties of superfluid helium. After a short historical review, I comment shortly on boiling and evaporation, then on the role of rotons and vortices in the existence of a critical velocity in superfluid helium. I finally discuss the existence of a condensate in a liquid with strong interactions, and the pressure variation of its superfluid transition temperature.Comment: Conference "Bose Einstein Condensation", Institut henri Poincare, Paris, 29 march 200

Catalysts, autocatalysis and the origin of metabolism

If life on Earth started out in geochemical environments like hydrothermal vents, then it started out from gasses like CO2, N2 and H2. Anaerobic autotrophs still live from these gasses today, and they still inhabit the Earth's crust. In the search for connections between abiotic processes in ancient geological systems and biotic processes in biological systems, it becomes evident that chemical activation (catalysis) of these gasses and a constant source of energy are key. The H2-CO2 redox reaction provides a constant source of energy and anabolic inputs, because the equilibrium lies on the side of reduced carbon compounds. Identifying geochemical catalysts that activate these gasses en route to nitrogenous organic compounds and small autocatalytic networks will be an important step towards understanding prebiotic chemistry that operates only on the basis of chemical energy, without input from solar radiation. So, if life arose in the dark depths of hydrothermal vents, then understanding reactions and catalysts that operate under such conditions is crucial for understanding origins

New constraints on coseismic slip during southern Cascadia subduction zone earthquakes over the past 4600 years implied by tsunami deposits and marine turbidites

This correction stands to correct Figure 7c listing a low minimum slip of 12 m for Case 2 instead of the correct value of 8 m, as stated in the body of the text and depicted on the chart of cumulative slip. The corrected chart explanation and caption are shown below. This error did not affect any of the findings of the paper or the chart itself. This is a correction to the original article

Spontaneous Stratification in Granular Mixtures

Granular materials size segregate when exposed to external periodic perturbations such as vibrations. Moreover, mixtures of grains of different sizes spontaneously segregate in the absence of external perturbations: when a mixture is simply poured onto a pile, the large grains are more likely to be found near the base, while the small grains are more likely to be near the top. Here, we report a spontaneous phenomenon arising when we pour a mixture between two vertical plates: the mixture spontaneously stratifies into alternating layers of small and large grains whenever the large grains are rougher than the small grains. In contrast, we find only spontaneous segregation when the large grains are more rounded than the small grains. The stratification is related to the occurrence of avalanches; during each avalanche the grains comprising the avalanche spontaneously stratify into a pair of layers through a "kink" mechanism, with the small grains forming a sublayer underneath the layer of large grains.Comment: 4 pages, 6 figures, http://polymer.bu.edu/~hmakse/Home.htm

Physical realization of coupled Hilbert-space mirrors for quantum-state engineering

Manipulation of superpositions of discrete quantum states has a mathematical counterpart in the motion of a unit-length statevector in an N-dimensional Hilbert space. Any such statevector motion can be regarded as a succession of two-dimensional rotations. But the desired statevector change can also be treated as a succession of reflections, the generalization of Householder transformations. In multidimensional Hilbert space such reflection sequences offer more efficient procedures for statevector manipulation than do sequences of rotations. We here show how such reflections can be designed for a system with two degenerate levels - a generalization of the traditional two-state atom - that allows the construction of propagators for angular momentum states. We use the Morris-Shore transformation to express the propagator in terms of Morris-Shore basis states and Cayley-Klein parameters, which allows us to connect properties of laser pulses to Hilbert-space motion. Under suitable conditions on the couplings and the common detuning, the propagators within each set of degenerate states represent products of generalized Householder reflections, with orthogonal vectors. We propose physical realizations of this novel geometrical object with resonant, near-resonant and far-off-resonant laser pulses. We give several examples of implementations in real atoms or molecules.Comment: 15 pages, 6 figure

Heterogeneity of impacts of high CO2 on the North Western European Shelf

The increase in atmospheric CO2 is a dual threat to the marine environment: from one side it drives climate change, leading to modifications in water temperature, circulation patterns and stratification intensity; on the other side it causes a decrease in marine pH (ocean acidification, or OA) due to the increase in dissolved CO2. Assessing the combined impact of climate change and OA on marine ecosystems is a challenging task. The response of the ecosystem to a single driver can be highly variable and remains still uncertain; additionally the interaction between these can be either synergistic or antagonistic. In this work we use the coupled oceanographic–ecosystem model POLCOMS-ERSEM driven by climate forcing to study the interaction between climate change and OA. We focus in particular on carbonate chemistry, primary and secondary production. The model has been run in three different configurations in order to assess separately the impacts of climate change on net primary production and of OA on the carbonate chemistry, which have been strongly supported by scientific literature, from the impact of biological feedbacks of OA on the ecosystem, whose uncertainty still has to be well constrained. The global mean of the projected decrease of pH at the end of the century is about 0.27 pH units, but the model shows significant interaction among the drivers and high variability in the temporal and spatial response. As a result of this high variability, critical tipping point can be locally and/or temporally reached: e.g. undersaturation with respect to aragonite is projected to occur in the deeper part of the central North Sea during summer. Impacts of climate change and of OA on primary and secondary production may have similar magnitude, compensating in some area and exacerbating in others

Longitudinal study of trachomatous trichiasis in The Gambia: barriers to acceptance of surgery.

PURPOSE: Investigation of compliance with surgery for trachomatous trichiasis has become a priority of the World Health Organization. This study was conducted to investigate attitudes toward trichiasis and its treatment and to determine the rate of surgical uptake in The Gambia. METHODS: A 1-year longitudinal study was performed in 190 subjects with trichiasis. Persons with major trichiasis (involving five lashes or more) were referred for surgery, and those with minor trichiasis were advised to epilate. Outcome measures included attitudes toward trichiasis and its treatment, reported barriers to surgical uptake, acceptance rates for surgery, and factors affecting acceptance. RESULTS: Twenty-three percent (95% confidence interval [CI] 16.5%-30.6%) of subjects with major trichiasis attended for surgery during the year. Degree of ignorance about surgery, symptoms impeding work, and a multiple income source for the head of household predicted attendance. Reported lack of time predicted nonattendance. Sixty-eight percent of patients who had undergone surgery were trichiasis free at last follow-up. CONCLUSIONS: Poor attendance for surgery remains a problem in The Gambia. Barriers include ignorance and lack of time and money. Health education and surgical delivery strategies are needed to overcome these barriers. Regular audit of surgical results is necessary, with retraining where indicated

Classifying atopic dermatitis: protocol for a systematic review of subtypes (phenotypes) and associated characteristics.

INTRODUCTION: Atopic dermatitis is a complex disease with differing clinical presentations. Many attempts have been made to identify uniform subtypes, or phenotypes, of atopic dermatitis in order to identify different aetiologies, improve diagnosis, estimate more accurate clinical prognoses, inform treatment andmanagement or predict treatment efficacy andeffectiveness. However, no consensus yet exists on exactly what defines these phenotypes or how many there are and whether they are genuine or statistical artefacts. This review aims to identify previously reported phenotypes of atopic dermatitis, the features used to define them and any characteristics or clinical outcomes significantly associated with them. METHODS AND ANALYSIS: We will search Ovid Embase, Ovid MEDLINE and Web of Science from inception to the latest available date at the time of the search for studies attempting to classify atopic dermatitis in humans using any cross-sectional or longitudinal epidemiological or interventional design. Primary outcomes are atopic dermatitis phenotypes, features used to define them and characteristics associated with them in subsequent analyses. A secondary outcome is the methodological approach used to derive them. Two reviewers will independently screen titles and abstracts for inclusion, extract data and assess study quality. We will present the results of this review descriptively and with frequencies where possible. ETHICS AND DISSEMINATION: Ethical approval is not required for this study as it is a systematic review. We will report results from this systematic review in a peer-reviewed journal. The main value of this study will be to inform further research. PROSPERO REGISTRATION NUMBER: CRD42018087500