1,484 research outputs found
Low Energy Properties of the Kondo chain in the RKKY regime
We study the Kondo chain in the regime of high spin concentration where the
low energy physics is dominated by the Ruderman-Kittel-Kasuya-Yosida (RKKY)
interaction. As has been recently shown (A. M. Tsvelik and O. M. Yevtushenko,
Phys. Rev. Lett 115, 216402 (2015)), this model has two phases with drastically
different transport properties depending on the anisotropy of the exchange
interaction. In particular, the helical symmetry of the fermions is
spontaneously broken when the anisotropy is of the easy plane type (EP). This
leads to a parametrical suppression of the localization effects. In the present
paper we substantially extend the previous theory, in particular, by analyzing
a competition of forward- and backward- scattering, including into the theory
short range electron interactions and calculating spin correlation functions.
We discuss applicability of our theory and possible experiments which could
support the theoretical findings.Comment: 24 pages, 8 figures, 5 appendice
Tuberculose in Nederland 2012
Op de gedrukte exemplaren van het rapport is het nummer 15000204. Het rapportnummer heeft een 0 te weinig; na versturing van de rapporten is dit pas opgemerktIn 2012 werden 958 patiënten met tuberculose gemeld aan het Nederlands Tuberculose Register (NTR). Dit komt overeen met een incidentie van tuberculose van 5,7 per 100.000 inwoners. Ten opzichte van 2011 en 2010 is de incidentie met respectievelijk vier procent en tien procent afgenomen. Sinds 2002 is het aantal tbc-patiënten in Nederland met 32% gedaald. In 2012 werd bij 53 procent van de gemelde patiënten longtuberculose geconstateerd. Het aantal patiënten met longtuberculose (pulmonale tbc) daalt sneller dan het aantal met extrapulmonale tbc (tuberculose buiten de longen). Het percentage extrapulmonale gevallen was het hoogste onder tbc-patiënten die in het buitenland zijn geboren. De meest voorkomende vorm van extrapulmonale tuberculose was tuberculose van de perifere lymfklieren. Achttien procent (177) van de tbc-patiënten in 2012 had sputumpositieve longtuberculose, de meest besmettelijke vorm van tuberculose. De incidentie van sputumpositieve longtuberculose in 2012 was 1,1 per 100.000 inwoners. Tuberculose komt in Nederland vaker voor bij personen geboren in het buitenland (eerstegeneratieallochtonen) en tweedegeneratieallochtonen. Bijna drie kwart van het aantal tbc-patiënten in 2012 was geboren in het buitenland (73%). Van de groep eerstegeneratieallochtonen met tuberculose in Nederland was de groep Somaliërs net als voorgaande jaren het grootste (170). Het percentage tbc-patiënten afkomstig uit Somalië was daarmee even groot als het percentage autochtone Nederlanders met tuberculose (18 procent), maar de incidentie onder Somaliërs in Nederland is bijna 500 maal hoger dan onder autochtone Nederlanders (respectievelijk 1,3 en 691 per 100.000 inwoners). Multiresistente tuberculose Het aantal patiënten met multiresistente tuberculose (MDR-tbc) in Nederland schommelt de laatste vijf jaar tussen tien en twintig patiënten; dat is 1-2% van het totaal aantal patiënten. In 2012 werden elf patiënten met multiresistente tuberculose gediagnosticeerd. Eén van de elf patiënten met mulitresistente tuberculose was afkomstig uit Nederland, de tien andere patiënten uit het buitenland. Resultaat van de behandeling Van alle in 2011 geregistreerde tbc-patiënten voltooide 87% de tbc-behandeling met succes. Bij nieuwe patiënten met longtuberculose was dit percentage iets lager (85%). Patiënten met multiresistente tuberculose voltooiden minder vaak de behandeling. Van de elf MDR-tbc-patiënten gediagnosticeerd in 2010 voltooiden zeven (64%) de behandeling met succes, één patiënt (9%) brak de behandeling voortijdig af, één patiënt zette de behandeling in het buitenland voort, één patiënt is overleden aan een andere oorzaak dan tuberculose en van één patiënt is het behandelresultaat (nog) niet bekend. Sterfte aan tuberculose Van de tbc-patiënten geregistreerd in het NTR in 2011 en 2012 overleden respectievelijk achttien (1,8%) en zes personen (0,6%) aan tuberculose. Patiënten met ernstige comorbiditeit hebben grotere kans op sterfte aan tuberculose. In 2012 overleed één persoon met diabetes, twee personen met een maligniteit en één persoon met nierinsufficiëntie aan tuberculose. Latente tbc-infectie (LTBI) In 2012 zijn 1.293 nieuwe gevallen van LTBI geregistreerd. Bij 855 personen werd de diagnose bij bron- en contactonderzoek vastgesteld. In 2011 startten in totaal 1.027 van de 1.297 personen (79%) een preventieve behandeling. Van hen voltooide 84% de LTBI-behandeling met succes. Delay Op grond van de gegevens in het NTR is de gemiddelde duur van het diagnostisch delay in de periode 2005-2012 niet toegenomen, hoewel bij illegalen, dak- en thuislozen, en drugs- en alcoholverslaafden wel aanwijzingen zijn voor een langer patient delay. Bij ruim een kwart van de patiënten die passief worden gevonden is wel sprake van een 'te lang' of 'ongunstig delay'. Voor doctor delay geldt hetzelfde: er is bij ruim een kwart van de patiënten die passief worden gevonden sprake van een 'te lang' of 'ongunstig delay'. Case finding In totaal 15% van alle tbc-patiënten werd in 2012 gevonden door actieve opsporing door de afdeling tbc-bestrijding van de GGD. Het percentage tbc-patiënten dat gevonden wordt door screening van risicogroepen zoals nieuwe immigranten, asielzoekers, drugsverslaafden en dak- en thuislozen neemt al langere tijd af. In de jaren 1993-1998 werd 14% van de tbc-patiënten gevonden door screening, maar in 2012 was dit nog maar 8%. Het percentage patiënten gevonden via bron- en contactonderzoek was in 2012 hetzelfde als in voorgaande jaren (7%). Tbc-patiënten met verminderde weerstand Het percentage tbc-patiënten met een co-infectie met hiv was 3% in 2012. Het percentage tbc-patiënten die op co-infectie met hiv werden getest nam toe van 28% in 2008 naar 49% in 2011, maar is in 2012gestagneerd (47%). Van patiënten uit risicogebieden zoals sub-Sahara Afrika was in 59% van de gevallen de hiv-status bekend. Het aantal tbc-patiënten die behandeld worden met TNF-alfaremmers neemt toe. In 2012 betrof het achttien (1,9%) patiënten. Transmissie en clustersurveillance Van de patiënten met kweekpositieve tuberculose clusterde de helft met een voorgaande patiënt. Bij een derde van de clusterende patiënten was sprake van recente clustering, een mogelijk gevolg van recente transmissie in Nederland. In 2012 vertoonden vier van de clusters een groei van meer dan vijf patiënten. De laatste jaren zijn er minder snelgroeiende clusters, een teken dat transmissie van M. tuberculosis in Nederland afneemt of dat de bestrijdingsmaatregelen effectief zijn.In 2012 958 cases of tuberculosis (TB) were reported to the Netherlands Tuberculosis Register (NTR). The incidence rate was 5.7 per 100,000 population. Since 2002 the number of TB patients in the Netherlands declined with 32%. In 2012 53% of the notified cases was diagnosed with pulmonary tuberculosis. Over the years the number of patients with extrapulmonary TB declined less than the number with pulmonary TB. The percentage extrapulmonary cases is highest among foreign-born TB patients. Tuberculosis of the extra thoracic lymph nodes is the most common site of disease in extrapulmonary cases. 18% (177) of all TB cases in 2012 was sputum-smear positive. The incidence rate of smear-positive pulmonary TB was 1.1 per 100,000 population. The majority of TB patients in the Netherlands was foreign-born (73%). As in previous years the largest population group with TB in 2012 was Somalian (170). The percentage of TB patients born in Somalia is in 2012 the same as the percentage native Dutch TB patients (18%). The incidence rate among people coming from Somalia is almost 500 times higher than the incidence rate of the native Dutch population (respectively 691 and 1.3 per 100,000 population). Multidrug-resistant tuberculosis In the last five years the number of patients with multidrug-resistant tuberculosis (MDR-TB) in the Netherlands varies between ten and twenty patients, 1-2% of the total number of TB patients. In 2012 eleven patients with MDR-TB were registered; ten were foreign-born. Treatment Outcome In 2011 87% of all TB patients completed treatment successfully. Of new cases with pulmonary TB 85% completed treatment successfully. Patients with MDR-TB completed treatment less often. Seven (64%) out of eleven MDR-TB-patients diagnosed in 2010 completed treatment successfully, one patient (9%) interrupted treatment, one patient continued treatment abroad, one patient died due to another cause than tuberculosis and of one patient treatment outcome is (still) unknown. TB-patients with co-morbidity or immune disorders The percentage of hiv-infected TB patients was 3% in 2012. The percentage TB patients tested for hiv increased from 28% in 2008 to 49% in 2011, but did not increase in 2012 (47%). Hiv-status was known in 59% of TB patients coming from sub-Saharan Africa, a hiv endemic area. The number of TB patients associated with TNF-alfa inhibitors treatment increases. In 2012 18 patients were registered (1.9%). Tuberculosis deaths Respectively 18 (1.8%) and 6 (0.6%) TB patients in 2011 and 2012 died due to tuberculosis. TB patients with serious co-morbidity have a higher risk of dying. In 2012 one person with diabetes, two persons with cancer and one person with renal insufficiency died due to tuberculosis. Respectively 20 (2.0%) and 20 (2.1%) TB patients in 2011 and 2012 died of other causes. Latent Tuberculosis Infection (LTBI) In 2012 1,293 new cases of LTBI were reported. 855 of these cases were detected through contact investigation. In 2011 1,027 of 1,297 cases (79%) started preventive treatment. Eighty-four percent of all persons with LTBI who received preventive treatment completed treatment successfully. Delay The mean length of the diagnostic delay over the years 2005-2012 did not increase, although undocumented TB patients, homeless TB patients, and drug and alcohol addicts with TB are associated with a longer patient delay. In more than a quarter of the passively detected cases a too long or 'unfavorable' patient delay was registered. This also applies to doctor delay; in more than a quarter of the passively detected cases a too long or 'unfavorable' delay was registered. Case finding Fifteen percent of all TB patients was detected by active case finding by the TB department of the Municipal Health Services. The percentage TB patients detected through screening of risk groups such as new immigrants, asylum seekers, drug addicts and homeless people has been decreasing for some time; in the years 1993-1998 14% of all TB patients was detected through screening, in 2012 only 8%. The number and percentage of cases found through contact investigation stayed more or less the same (7%). Transmission and cluster surveillance In 2012 50% of the cases with a positive culture belonged to a cluster. In one third of these cases recent clustering was registered, possibly as a result of recent transmission in the Netherlands. In 2012 four existing clusters showed growth of more than five patients. In the last few years there were no large outbreaks registered in the Netherlands
Advanced atomic force microscopy techniques
Cataloged from PDF version of article.Although its conceptual approach is as simple as the technique used in record players already introduced in the 19th century, the invention of the atomic force microscope (AFM) in 1986 by Binnig, Quate, and Gerber was a milestone for nanotechnology. The scanning tunneling microscope (STM), introduced some years earlier, had already achieved atomic resolution, but is limited to conductive surfaces. Since its operational principle is based on the detection of the forces acting between tip and sample, this restriction does not exist for the AFM. Consequently, atomic force microscopy quickly became the standard tool for nanometer-scale imaging of all types of surfaces in all environments. True atomic resolution was first achieved in the 1990s. The most convincing results, however, were restricted to the so-called noncontact mode in vacuum for a long time, but recent technical developments overcame this limitation, and atomic-resolution imaging is now also a standard in liquids.
Beyond pushing the resolution limit to the picometer range, the invention of the AFM triggered the development of a growing number of new scanning probe methods and approaches, ranging from an expansion of the properties that can be mapped to the active manipulation of surfaces and small particles. Practically every month, reports on the growing capabilities of AFMs appear. Nearly every physical effect that influences the tip–sample interaction has been used to improve existing modes and to develop new ones. For example, many recently presented techniques include the excitation of higher cantilever oscillation modes; it is amazing in how many ways the shaking of a simple cantilever can improve our knowledge about the tip–sample interaction. Another direction is high-speed atomic force microscopy, which is one of the eminent challenges that need to be solved in order to allow the in situ observation of biological processes. Data acquisition times have already reached the millisecond range, enabling the visualization of the dynamic behavior of biological molecules and cells. Other recent accomplishments include imaging of organic molecules with unprecedented resolution, full three-dimensional mapping of surface force fields, and the imaging and discrimination of individual chemical bonds.
The development of advanced techniques is the focus of this Thematic Series, following the Thematic Series “Scanning probe microscopy and related techniques” edited by Ernst Meyer and the Thematic Series “Noncontact atomic force microscopy” edited by Udo Schwarz. The articles that are part of the series demonstrate that, despite its 25 years of history, the AFM is still far from reaching its limits, and today’s developments are far-reaching. As the number of research groups utilizing advanced atomic force microscopy techniques increases with each passing year, the technical improvements, data-acquisition approaches, analysis procedures, user friendliness, and application areas of the technique further diversify. With this Thematic Series, it is our intention to stimulate these improvements.
We thank all authors for contributing their excellent work to this series. Furthermore, we acknowledge all referees for their promptly provided reports keeping the publication times short and attractive for contributors. Finally, we are grateful to the open access policy of the Beilstein Journal of Nanotechnology providing the ground for unrestricted discussions on advanced atomic force microscopy techniques.
Thilo Glatzel, Hendrik Hölscher, Thomas Schimmel, Mehmet Z. Baykara, Udo D. Schwarz and Ricardo Garcia
December 201
Measurement of mechanical vibrations excited in aluminium resonators by 0.6 GeV electrons
We present measurements of mechanical vibrations induced by 0.6 GeV electrons
impinging on cylindrical and spherical aluminium resonators. To monitor the
amplitude of the resonator's vibrational modes we used piezoelectric ceramic
sensors, calibrated by standard accelerometers. Calculations using the
thermo-acoustic conversion model, agree well with the experimental data, as
demonstrated by the specific variation of the excitation strengths with the
absorbed energy, and with the traversing particles' track positions. For the
first longitudinal mode of the cylindrical resonator we measured a conversion
factor of 7.4 +- 1.4 nm/J, confirming the model value of 10 nm/J. Also, for the
spherical resonator, we found the model values for the L=2 and L=1 mode
amplitudes to be consistent with our measurement. We thus have confirmed the
applicability of the model, and we note that calculations based on the model
have shown that next generation resonant mass gravitational wave detectors can
only be expected to reach their intended ultra high sensitivity if they will be
shielded by an appreciable amount of rock, where a veto detector can reduce the
background of remaining impinging cosmic rays effectively.Comment: Tex-Article with epsfile, 34 pages including 13 figures and 5 tables.
To be published in Rev. Scient. Instr., May 200
‘O sibling, where art thou?’ – a review of avian sibling recognition with respect to the mammalian literature
Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where ‘mixing potential’ of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through ‘direct familiarisation’ (commonly known as associative learning or familiarity); future experiments should also incorporate tests for ‘indirect familiarisation’ (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic
Constraints on rigid zones and other distinct layers at the top of the outer core using CMB underside reflected PKKP waves
High-power operation of coherently coupled tapered laser diodes in an external cavity
We demonstrate a rear-side phase-locking architecture with two high-brightness diode lasers. This technique is based on the passive phase-locking of emitters in an external cavity on their rear facet, and their coherent combination on the front facet. Two high-brightness high-power tapered laser diodes are coherently combined using a Michelson-based cavity. The combining efficiency is above 80% and results in an output power of 6.7 W in a nearly diffraction-limited beam. The rear-side architecture is then used with a laser bar of 5 tapered emitters using an interferometric extended cavity, based on a diffractive optical element. We describe the experimental evaluation of the diffractive optical element, and the phase-locked operation of the laser bar
Repellent Effects on Distribution of Steers on Native Range
Poor distribution of livestock use over a range is a common limitation to proper and optimum use of many ranges. When the range is a common limitation to proper and optimum use of many ranges. When the range as a whole is properly used, livestock typically overuse those areas that are especially attractive to them. Use of conventional distribution tools are sometimes inappropriate or ineffective in correcting livestock distribution problems. This study evaluated a commercially available big game repellent for deterring yearling steer use of preferred grazing areas. Repellent sprayed areas had fewer cow chips (P\u3c.10) 1 week following application on subirrigated range sites but not on silty range sites. In general, treatment did not deter occupation of yearling steers on preferred grazing areas around potholes
Increased masticatory activity and quality of life in elderly persons with dementia-a longitudinal matched cluster randomized single-blind multicenter intervention study.
Background: Worldwide, millions of people are suffering from dementia and this number is rising. An index of quality of life (QoL) can describe the impact a disease or treatment has on a person's wellbeing. QoL comprises many variables, including physical health and function, and mental health and function. QoL is related to masticatory ability and physical activity. Animal studies show that disruption of mastication due to loss of teeth or a soft diet leads to memory loss and learning problems. Since these are common complaints in dementia, it is hypothesized that improvement of masticatory function and normalization of diet consistency can increase QoL in elderly persons suffering from dementia. Therefore, the goal of the present study is to examine whether an increase in masticatory activity, achieved by increased food consistency and enhancement of masticatory function through improved oral health care has a positive effect on QoL, including cognition, mood, activities of daily living (ADL), and circadian rhythm in elderly persons with dementia.Methods and design: The described study is a prospective longitudinal matched cluster randomized single-blind multicenter study. Participants are elderly persons living in the Netherlands, suffering from dementia and receiving psychogeriatric care. An intervention group will receive improved oral health care and a diet of increased consistency. A control group receives care as usual. Participants will be assessed four times; outcome variables besides QoL are cognition, mood, independence, rest-activity rhythm, blood pressure, and masticatory function.Discussion: This research protocol investigates the effect of an intervention executed by daily caregivers. The intervention will increase masticatory activity, which is achieved by three different actions, (providing oral health care, increasing food consistency, or a combination of both). There is a certain amount of variety in the nature of the interventions due to local differences in nursing homes. This might be a scientific weakness in the study design; however, a practical implementation of any findings will be subject to the same factors, making this study design clinically relevant.Trial registration: NTR1561. © 2013 Weijenberg et al.; licensee BioMed Central Ltd
Ancient horizontal gene transfer and the last common ancestors
Background
The genomic history of prokaryotic organismal lineages is marked by extensive horizontal gene transfer (HGT) between groups of organisms at all taxonomic levels. These HGT events have played an essential role in the origin and distribution of biological innovations. Analyses of ancient gene families show that HGT existed in the distant past, even at the time of the organismal last universal common ancestor (LUCA). Most gene transfers originated in lineages that have since gone extinct. Therefore, one cannot assume that the last common ancestors of each gene were all present in the same cell representing the cellular ancestor of all extant life.
Results
Organisms existing as part of a diverse ecosystem at the time of LUCA likely shared genetic material between lineages. If these other lineages persisted for some time, HGT with the descendants of LUCA could have continued into the bacterial and archaeal lineages. Phylogenetic analyses of aminoacyl-tRNA synthetase protein families support the hypothesis that the molecular common ancestors of the most ancient gene families did not all coincide in space and time. This is most apparent in the evolutionary histories of seryl-tRNA synthetase and threonyl-tRNA synthetase protein families, each containing highly divergent “rare” forms, as well as the sparse phylogenetic distributions of pyrrolysyl-tRNA synthetase, and the bacterial heterodimeric form of glycyl-tRNA synthetase. These topologies and phyletic distributions are consistent with horizontal transfers from ancient, likely extinct branches of the tree of life.
Conclusions
Of all the organisms that may have existed at the time of LUCA, by definition only one lineage is survived by known progeny; however, this lineage retains a genomic record of heterogeneous genetic origins. The evolutionary histories of aminoacyl-tRNA synthetases (aaRS) are especially informative in detecting this signal, as they perform primordial biological functions, have undergone several ancient HGT events, and contain many sites with low substitution rates allowing deep phylogenetic reconstruction. We conclude that some aaRS families contain groups that diverge before LUCA. We propose that these ancient gene variants be described by the term “hypnologs”, reflecting their ancient, reticulate origin from a time in life history that has been all but erased”.National Science Foundation (U.S.) (Grant DEB 0830024)Exobiology Program (U.S.) (Grant NNX10AR85G)United States. National Aeronautics and Space Administration (Postdoctoral Program
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