106 research outputs found

    Correlations of Rydberg excitations in an ultra-cold gas after an echo sequence

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    We show that Rydberg states in an ultra-cold gas can be excited with strongly preferred nearest-neighbor distance if densities are well below saturation. The scheme makes use of an echo sequence in which the first half of a laser pulse excites Rydberg states while the second half returns atoms to the ground state, as in the experiment of Raitzsch et al. [Phys. Rev. Lett. 100 (2008) 013002]. Near to the end of the echo sequence, almost any remaining Rydberg atom is separated from its next-neighbor Rydberg atom by a distance slightly larger than the instantaneous blockade radius half-way through the pulse. These correlations lead to large deviations of the atom counting statistics from a Poissonian distribution. Our results are based on the exact quantum evolution of samples with small numbers of atoms. We finally demonstrate the utility of the omega-expansion for the approximate description of correlation dynamics through an echo sequence.Comment: 8 pages, 6 figure

    Primary treatment of acromegaly with high-dose lanreotide: a case series

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    <p>Abstract</p> <p>Introduction</p> <p>The first-line treatment for acromegaly is transsphenoidal surgery. In approximately 50% of patients, however, a cure is not possible with surgery and alternatives are needed. Somatostatin analog therapy is the recommended first-line treatment in patients with such cases. Here we provide the first report of a high-dose lanreotide primary therapy in patients with acromegaly.</p> <p>Case presentation</p> <p>Six patients who were not suitable for surgery were given 60 mg of lanreotide (Autogel<sup>®</sup>) every four weeks. All patients were German nationals and Caucasian.</p> <p>When the response of our patients was unsatisfactory, the dose was increased sequentially to 90 mg every four weeks, 120 mg every four weeks, 120 mg every three weeks and 180 mg every three weeks. Treatment duration was 12 to 24 months. In all cases, the lanreotide dose was 120 mg every 4 weeks or higher. In five of our patients, growth hormone (GH) levels were successfully reduced (in three patients GH <2.5 ng/ml was achieved). Insulin-like growth factor 1 levels were normalized in three patients and decreased in two patients. One patient failed to show a biochemical response to lanreotide therapy or pegvisomant therapy.</p> <p>Tumor shrinkage or degeneration was observed in the five responding patients. No drug-related adverse events were noted.</p> <p>Conclusions</p> <p>These results suggest that lanreotide at high doses of 120 mg every four weeks or more is an effective first-line therapy for patients with acromegaly that surgery alone cannot treat.</p

    Microbial adaptation to venom is common in snakes and spiders

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    Animal venoms are considered sterile sources of antimicrobial compounds with strong membrane disrupting activity against multi-drug resistant bacteria. However, bite wound infections are common in developing nations. Investigating the oral and venom microbiome of five snake and two spider species, we evidence viable microorganisms potentially unique to venom for black-necked spitting cobras (Naja nigricollis). Among these are two novel sequence types of Enterococcus faecalis misidentified by commonly used clinical biochemistry procedures as Staphylococcus; the genome sequence data of venom-specific isolates feature an additional 45 genes, at least 11 of which improve membrane integrity. Our findings challenge the dogma of venom sterility and indicate an increased primary infection risk in the clinical management of venomous animal bite wounds

    Theory of Multidimensional Solitons

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    We review a number of topics germane to higher-dimensional solitons in Bose-Einstein condensates. For dark solitons, we discuss dark band and planar solitons; ring dark solitons and spherical shell solitons; solitary waves in restricted geometries; vortex rings and rarefaction pulses; and multi-component Bose-Einstein condensates. For bright solitons, we discuss instability, stability, and metastability; bright soliton engineering, including pulsed atom lasers; solitons in a thermal bath; soliton-soliton interactions; and bright ring solitons and quantum vortices. A thorough reference list is included.Comment: review paper, to appear as Chapter 5a in "Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer-Verlag

    Historic genetic structuring and paraphyly within the Great-tailed Grackle

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    The Great-tailed Grackle (Quiscalus mexicanus) and Boat-tailed Grackle (Q. major) are sister species that have expanded their ranges during historical times. This expansion has created an area of sympatry between these species in Texas and Louisiana, and between distinctive Great-tailed Grackle subspecies in the southwestern United States and northern Mexico. We investigated the evolutionary histories of both species using mitochondrial DNA sequence data and modern phylogenetic methods. Our results reveal genetic structure within Great-tailed, but not Boat-tailed Grackles. Great-tailed Grackles are separated into two clades, but range expansion in the north has led to secondary contact between them. Boat-tailed Grackles are monophyletic and are embedded within the Great-tailed Grackle assemblage, rendering the latter paraphyletic. These results reveal a complex phylogeographic pattern caused by recent range expansion and secondary contact of once allopatric units

    Deconstructing compassionate conservation

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    Compassionate conservation focuses on 4 tenets: first, do no harm; individuals matter; inclusivity of individual animals; and peaceful coexistence between humans and animals. Recently, compassionate conservation has been promoted as an alternative to conventional conservation philosophy. We believe examples presented by compassionate conservationists are deliberately or arbitrarily chosen to focus on mammals; inherently not compassionate; and offer ineffective conservation solutions. Compassionate conservation arbitrarily focuses on charismatic species, notably large predators and megaherbivores. The philosophy is not compassionate when it leaves invasive predators in the environment to cause harm to vastly more individuals of native species or uses the fear of harm by apex predators to terrorize mesopredators. Hindering the control of exotic species (megafauna, predators) in situ will not improve the conservation condition of the majority of biodiversity. The positions taken by so-called compassionate conservationists on particular species and on conservation actions could be extended to hinder other forms of conservation, including translocations, conservation fencing, and fertility control. Animal welfare is incredibly important to conservation, but ironically compassionate conservation does not offer the best welfare outcomes to animals and is often ineffective in achieving conservation goals. Consequently, compassionate conservation may threaten public and governmental support for conservation because of the limited understanding of conservation problems by the general public

    Bacterial Adaptation to Venom in Snakes and Arachnida

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    Animal venoms are considered sterile sources of antimicrobial compoundswith strong membrane-disrupting activity against multidrug-resistant bacteria. However,venomous bite wound infections are common in developing nations. Investigating theenvenomation organ and venom microbiota offive snake and two spider species, weobserved venom community structures that depend on the host venomous animal spe-cies and evidenced recovery of viable microorganisms from black-necked spitting cobra(Naja nigricollis) and Indian ornamental tarantula (Poecilotheria regalis) venoms. Amongthe bacterial isolates recovered fromN. nigricollis,weidentified two venom-resistant,novel sequence types ofEnterococcus faecaliswhose genomes feature 16 virulencegenes, indicating infectious potential, and 45 additional genes, nearly half of whichimprove bacterial membrane integrity. Ourfindings challenge the dogma of venom ste-rility and indicate an increased primary infection risk in the clinical management of ven-omous animal bite wounds

    Predation and the Maintenance of Color Polymorphism in a Habitat Specialist Squamate

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    Multiple studies have addressed the mechanisms maintaining polymorphism within a population. However, several examples exist where species inhabiting diverse habitats exhibit local population-specific polymorphism. Numerous explanations have been proposed for the maintenance of geographic variation in color patterns. For example, spatial variation in patterns of selection or limited gene flow can cause entire populations to become fixed for a single morph, resulting in separate populations of the same species exhibiting separate and distinct color morphs. The mottled rock rattlesnake (Crotalus lepidus lepidus) is a montane species that exhibits among-population color polymorphism that correlates with substrate color. Habitat substrate in the eastern part of its range is composed primarily of light colored limestone and snakes have light dorsal coloration, whereas in the western region the substrate is primarily dark and snakes exhibit dark dorsal coloration. We hypothesized that predation on high contrast color and blotched patterns maintain these distinct color morphs. To test this we performed a predation experiment in the wild by deploying model snakes at 12 sites evenly distributed within each of the two regions where the different morphs are found. We employed a 2×2 factorial design that included two color and two blotched treatments. Our results showed that models contrasting with substrate coloration suffered significantly more avian attacks relative to models mimicking substrates. Predation attempts on blotched models were similar in each substrate type. These results support the hypothesis that color pattern is maintained by selective predation

    Clinical efficacy and safety results for dose escalation of somatostatin receptor ligands in patients with acromegaly: a literature review

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    Acromegaly is a rare disease with a multifaceted clinical presentation. In 90–95% of patients with acromegaly, the disease is caused by a growth hormone (GH)-secreting pituitary adenoma with elevated GH levels that ultimately induce excessive hepatic secretion of insulin-like growth factor-1 (IGF-1). Somatostatin receptor ligands (SRLs) are considered the standard medical choice for the treatment of acromegaly, and normalization of GH and IGF-1 is attainable with effective therapy. This review aims to summarize the literature relative to SRL dose escalation therapy in patients with acromegaly. A United States National Library of Medicine PubMed search of SRL’s was conducted using the following search terms: ((((LAR) OR ATG) OR octreotide) OR lanreotide Autogel) AND acromegaly. Related articles in non peer-reviewed journals were excluded. The rationale and benefits of SRL dose optimization therapy were investigated with emphasis on describing the clinical recognition, treatment, and management of patients with acromegaly. We found that dose escalation could provide additional biochemical control of acromegaly in patients who are inadequately controlled with conventional starting doses of octreotide LAR and lanreotide Autogel®. Furthermore, patients should routinely have their GH and IGF-1 levels closely monitored and their SRL dose increased or decreased thereafter according to individual response

    FRAX™ and the assessment of fracture probability in men and women from the UK

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    SUMMARY: A fracture risk assessment tool (FRAX) is developed based on the use of clinical risk factors with or without bone mineral density tests applied to the UK. INTRODUCTION: The aim of this study was to apply an assessment tool for the prediction of fracture in men and women with the use of clinical risk factors (CRFs) for fracture with and without the use of femoral neck bone mineral density (BMD). The clinical risk factors, identified from previous meta-analyses, comprised body mass index (BMI, as a continuous variable), a prior history of fracture, a parental history of hip fracture, use of oral glucocorticoids, rheumatoid arthritis and other secondary causes of osteoporosis, current smoking, and alcohol intake 3 or more units daily. METHODS: Four models were constructed to compute fracture probabilities based on the epidemiology of fracture in the UK. The models comprised the ten-year probability of hip fracture, with and without femoral neck BMD, and the ten-year probability of a major osteoporotic fracture, with and without BMD. For each model fracture and death hazards were computed as continuous functions. RESULTS: Each clinical risk factor contributed to fracture probability. In the absence of BMD, hip fracture probability in women with a fixed BMI (25 kg/m(2)) ranged from 0.2% at the age of 50 years for women without CRF's to 22% at the age of 80 years with a parental history of hip fracture (approximately 100-fold range). In men, the probabilities were lower, as was the range (0.1 to 11% in the examples above). For a major osteoporotic fracture the probabilities ranged from 3.5% to 31% in women, and from 2.8% to 15% in men in the example above. The presence of one or more risk factors increased probabilities in an incremental manner. The differences in probabilities between men and women were comparable at any given T-score and age, except in the elderly where probabilities were higher in women than in men due to the higher mortality of the latter. CONCLUSION: The models provide a framework which enhances the assessment of fracture risk in both men and women by the integration of clinical risk factors alone and/or in combination with BMD
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