Lateral vegetation growth rates exert control on coastal foredune hummockiness and coalescing time

Coastal foredunes form along sandy, low-sloped coastlines and range in shape from continuous dune ridges to hummocky features, which are characterized by alongshore-variable dune crest elevations. Initially scattered dune-building plants and species that grow slowly in the lateral direction have been implicated as a cause of foredune hummockiness . Our goal in this work is to explore how the initial configuration of vegetation and vegetation growth characteristics control the development of hummocky coastal dunes including the maximum hummockiness of a given dune field. We find that given sufficient time and absent external forcing, hummocky foredunes coalesce to form continuous dune ridges. Model results yield a predictive rule for the timescale of coalescing and the height of the coalesced dune that depends on initial plant dispersal and two parameters that control the lateral and vertical growth of vegetation, respectively. Our findings agree with previous observational and conceptual work - whether or not hummockiness will be maintained depends on the timescale of coalescing relative to the recurrence interval of high-water events that reset dune building in low areas between hummocks. Additionally, our model reproduces the observed tendency for foredunes to be hummocky along the southeast coast of the US where lateral vegetation growth rates are slower and thus coalescing times are likely longer

BPS Monopole Equation in Omega-background

We study deformed supersymmetries in N=2 super Yang-Mills theory in the Omega-backgrounds characterized by two complex parameters $\epsilon_1, \epsilon_2$. When one of the $\epsilon$-parameters vanishes, the theory has extended supersymmetries. We compute the central charge of the algebra and obtain the deformed BPS monopole equation. We examine supersymmetries preserved by the equation.Comment: 14 pages, typos corrected, published version in JHE

Counting Exceptional Instantons

We show how to obtain the instanton partition function of N=2 SYM with exceptional gauge group EFG using blow-up recursion relations derived by Nakajima and Yoshioka. We compute the two instanton contribution and match it with the recent proposal for the superconformal index of rank 2 SCFTs with E6, E7 global symmetry.Comment: 16 pages, references adde

Primary Health Centre disaster preparedness after the earthquake in Padang Pariaman, West Sumatra, Indonesia

<p>Abstract</p> <p>Background</p> <p>The West Sumatra earthquake that occurred on September 30, 2009, caused severe damage in some districts, including Padang Pariaman. As Padang Pariaman is an earthquake-prone area, disaster and emergency management is necessary. Due to the limited health facilities, the health services completely rely on Puskesmas (Primary Health Centres, PHCs). This study is aimed at assessing the preparedness of PHCs to response to potential disasters in their surrounding area.</p> <p>Findings</p> <p>Padang Pariaman district was used in a case study setting to assess the readiness and preparedness of the PHCs there to face disasters. Self-administered questionnaire, key informant interview, and direct observation were used to obtain the data on human resources, facilities preparedness, and the procedures. The investigation focused on measuring four aspects, i.e. human resources, facilities preparedness, standard operating procedure (SOP), and policy. Due to the limited co-operation of the head of the PHCs, three PHCs were directly observed as a subsample. The evaluation was performed six months after the impact phase of the earthquake and three months after the PHCs' health staff training on improving the primary health care services. The number and quality of health staff in Padang Pariaman was far below ideal. Fewer than half of the PHCs had emergency facilities and only one considered the need for triage and fire management, whereas the transportation mode was still limited. An SOP and policy for facing disasters were not available in any of the PHCs. Therefore, promoting disaster preparedness, technical provision, including health staff training, is necessary.</p> <p>Conclusions</p> <p>Padang Pariaman district has not yet prepared its PHCs to face disaster, so it is apparent that PHCs' disaster preparedness in Padang Pariaman and also other earthquake-prone areas in Indonesia should be promoted. This should include increasing the number of doctors, providing training for health staff, and developing a comprehensive approach as well as coordination among government, hospitals, PHCs, and NGO's for disaster preparedness.</p

Carotid axillary bypass in a patient with blocked subclavian stents: a case report

<p>Abstract</p> <p>Introduction</p> <p>Surgical treatment of symptomatic occlusive lesions of the proximal subclavian artery is infrequently necessary. Carotid subclavian bypass has gained popularity and is now considered standard treatment when stenting is not possible. Exposure of the subclavian artery and bypass grafting onto it is difficult, as the vessel is delicate, thin-walled and located deep in the supraclavicular fossa. The thoracic duct and brachial plexus are in close proximity to the left subclavian artery and are therefore susceptible to damage. Distal grafting to the axillary artery instead of the subclavian artery has the potential of avoiding some of these risks. Infraclavicular exposure of the axillary artery is more straightforward. The vessel wall is thicker and is easier to handle. In this case report, we describe a patient with a left proximal subclavian occlusion which was stented twice and blocked on both occasions. The patient underwent a carotid axillary bypass, as grafting onto the subclavian artery was impossible because of the two occluded metal stents.</p> <p>Case presentation</p> <p>A 56-year-old Caucasian woman, a heavy smoker, presented acutely with left arm numbness and pain and blood pressure discrepancies in both arms. A diagnosis of subclavian stenosis was confirmed on the basis of a computed tomographic scan and a magnetic resonance angiogram. The patient had undergone subclavian artery stenting twice, and unfortunately the stents blocked on both occasions. The patient underwent carotid axillary bypass surgery. She had an uneventful recovery and was able to return to a full, normal life.</p> <p>Conclusion</p> <p>Carotid axillary bypass appears to be a good alternative to carotid subclavian bypass in the treatment of symptomatic proximal stenosis or occlusion of the subclavian artery.</p

A Survey on Continuous Time Computations

We provide an overview of theories of continuous time computation. These theories allow us to understand both the hardness of questions related to continuous time dynamical systems and the computational power of continuous time analog models. We survey the existing models, summarizing results, and point to relevant references in the literature

Nitrogen transfer from forage legumes to nine neighbouring plants in a multi-species grassland

Legumes play a crucial role in nitrogen supply to grass-legume mixtures for ruminant fodder. To quantify N transfer from legumes to neighbouring plants in multi-species grasslands we established a grass-legume-herb mixture on a loamy-sandy site in Denmark. White clover (Trifolium repens L.), red clover (Trifolium pratense L.) and lucerne (Medicago sativa L.) were leaf-labelled with 15N enriched urea during one growing season. N transfer to grasses (Lolium perenne L. and xfestulolium), white clover, red clover, lucerne, birdsfoot trefoil (Lotus corniculatus L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.), salad burnet (Sanguisorba minor L.)and caraway (Carum carvi L.) was assessed. Neighbouring plants contained greater amounts of N derived from white clover (4.8 gm-2) compared with red clover (2.2 gm-2) and lucerne (1.1 gm-2). Grasses having fibrous roots received greater amounts of N from legumes than dicotyledonous plants which generally have taproots. Slurry application mainly increased N transfer from legumes to grasses. During the growing season the three legumes transferred approximately 40 kg N ha-1 to neighbouring plants. Below-ground N transfer from legumes to neighbouring plants differed among nitrogen donors and nitrogen receivers and may depend on root characteristics and regrowth strategies of plant species in the multi-species grassland

Chaotic dynamics of falling disks

The study of the motion of flat bodies falling in a viscous medium dates back at least to Newton(1) and Maxwell(2), and is relevant to problems in meteorology(3), sedimentology(4), aerospace engineering(1) and chemical engineering(5-8). More recent theoretical studies(9-12) have emphasized the role played by deterministic chaos, although many experimental studies(1,5-8,13,14) were performed before the development of such ideas. Here we report experimental observations of the dynamics of disks falling in water/glycerol mixtures. We find four distinct types of motion, which are mapped out in a 'phase diagram'. The apparently complex behaviour can be reduced to a series of one-dimensional maps, which display a discontinuity at the crossover from periodic to chaotic motion. This discontinuity leads to an unusual intermittency transition(15), not previously observed experimentally, between the two behaviours.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62793/1/388252a0.pd

Entropy-driven liquid-liquid separation in supercooled water

Twenty years ago Poole et al. (Nature 360, 324, 1992) suggested that the anomalous properties of supercooled water may be caused by a critical point that terminates a line of liquid-liquid separation of lower-density and higher-density water. Here we present an explicit thermodynamic model based on this hypothesis, which describes all available experimental data for supercooled water with better quality and with fewer adjustable parameters than any other model suggested so far. Liquid water at low temperatures is viewed as an 'athermal solution' of two molecular structures with different entropies and densities. Alternatively to popular models for water, in which the liquid-liquid separation is driven by energy, the phase separation in the athermal two-state water is driven by entropy upon increasing the pressure, while the critical temperature is defined by the 'reaction' equilibrium constant. In particular, the model predicts the location of density maxima at the locus of a near-constant fraction (about 0.12) of the lower-density structure.Comment: 7 pages, 6 figures. Version 2 contains an additional supplement with tables for the mean-field equatio

Long term in-vivo studies of a photo-oxidized bovine osteochondral transplant in sheep

BACKGROUND: Articular cartilage has limited capacity to repair. Defects greater than 3 mm heal with formation of inferior fibrous cartilage. Therefore, many attempts have been made to find the ideal graft for larger cartilage lesions. Different grafts, such as untreated or cryopreserved osteochondral transplants, have been used with variable success. METHODS: Photo-oxidized osteochondral grafts were implanted in both femoral condyles of one ovine knee. Untreated xenogeneic and autogeneic grafts served as controls. Three groups of 8 sheep each were formed and they were sacrificed 6, 12 or 18 months after surgery. RESULTS: The macroscopic evaluation of the condyle and graft showed a well-maintained cartilage surface in most grafts at all time points. However, the host cartilage matrix deteriorated considerably in all xenogeneic, most autogeneic and fewer of the photo-oxidized grafts at 12 and 18 months, respectively. The blue colour of the photo-oxidized grafts resulting from the process of photo-oxidation was visible in all grafts at 6 months, had diminished at 12 months and had completely disappeared at 18 months after surgery. Histologically a loss of matrix staining was almost never noticed in untreated xenografts, transiently at 6 months in photo-oxidized grafts and increased at 12 and 18 months. Fusion between graft and host cartilage could be seen in photo-oxidized grafts at 12 and 18 months, but was never seen in autografts and xenografts. CONCLUSIONS: The photo-oxidation of osteochondral grafts and its use as transplant appears to have a beneficial effect on cartilage and bone remodelling. Osteochondral grafts pre-treated with photo-oxidation may be considered for articular cartilage replacement and therefore may delay artificial joint replacements in human patients