611 research outputs found

    Carrier-envelope phase effects on the strong-field photoemission of electrons from metallic nanostructures

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    Sharp metallic nanotapers irradiated with few-cycle laser pulses are emerging as a source of highly confined coherent electron wavepackets with attosecond duration and strong directivity. The possibility to steer, control or switch such electron wavepackets by light is expected to pave the way towards direct visualization of nanoplasmonic field dynamics and real-time probing of electron motion in solid state nanostructures. Such pulses can be generated by strong-field induced tunneling and acceleration of electrons in the near-field of sharp gold tapers within one half-cycle of the driving laser field. Here, we show the effect of the carrier-envelope phase of the laser field on the generation and motion of strong-field emitted electrons from such tips. This is a step forward towards controlling the coherent electron motion in and around metallic nanostructures on ultrashort length and time scales

    Cardiac lipid content is unresponsive to a physical activity training intervention in type 2 diabetic patients, despite improved ejection fraction

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    Background: Increased cardiac lipid content has been associated with diabetic cardiomyopathy. We recently showed that cardiac lipid content is reduced after 12 weeks of physical activity training in healthy overweight subjects. The beneficial effect of exercise training on cardiovascular risk is well established and the decrease in cardiac lipid content with exercise training in healthy overweight subjects was accompanied by improved ejection fraction. It is yet unclear whether diabetic patients respond similarly to physical activity training and whether a lowered lipid content in the heart is necessary for improvements in cardiac function. Here, we investigated whether exercise training is able to lower cardiac lipid content and improve cardiac function in type 2 diabetic patients. Methods: Eleven overweight-to-obese male patients with type 2 diabetes mellitus (age: 58.4 +/- 0.9 years, BMI: 29.9 +/- 0.01 kg/m(2)) followed a 12-week training program (combination endurance/strength training, three sessions/week). Before and after training, maximal whole body oxygen uptake (VO2max) and insulin sensitivity (by hyperinsulinemic, euglycemic clamp) was determined. Systolic function was determined under resting conditions by CINE-MRI and cardiac lipid content in the septum of the heart by Proton Magnetic Resonance Spectroscopy. Results: VO2max increased (from 27.1 +/- 1.5 to 30.1 +/- 1.6 ml/min/kg, p = 0.001) and insulin sensitivity improved upon training (insulin stimulated glucose disposal (delta Rd of glucose) improved from 5.8 +/- 1.9 to 10.3 +/- 2.0 mu mol/kg/min, p = 0.02. Left-ventricular ejection fraction improved after training (from 50.5 +/- 2.0 to 55.6 +/- 1.5%, p = 0.01) as well as cardiac index and cardiac output. Unexpectedly, cardiac lipid content in the septum remained unchanged (from 0.80 +/- 0.22% to 0.95 +/- 0.21%, p = 0.15). Conclusions: Twelve weeks of progressive endurance/strength training was effective in improving VO(2)max, insulin sensitivity and cardiac function in patients with type 2 diabetes mellitus. However, cardiac lipid content remained unchanged. These data suggest that a decrease in cardiac lipid content in type 2 diabetic patients is not a prerequisite for improvements in cardiac function.Cardiovascular Aspects of Radiolog

    Assessment of anti-inflammatory tumor treatment efficacy by longitudinal monitoring employing sonographic micro morphology in a preclinical mouse model

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    <p>Abstract</p> <p>Background</p> <p>With the development of increasingly sophisticated three-dimensional volumetric imaging methods, tumor volume can serve as a robust and reproducible measurement of drug efficacy. Since the use of molecularly targeted agents in the clinic will almost certainly involve combinations with other therapeutic modalities, the use of volumetric determination can help to identify a dosing schedule of sequential combinations of cytostatic drugs resulting in long term control of tumor growth with minimal toxicity. The aim of this study is to assess high resolution sonography imaging for the in vivo monitoring of efficacy of Infliximab in pancreatic tumor.</p> <p>Methods</p> <p>In the first experiment, primary orthotopic pancreatic tumor growth was measured with Infliximab treatment. In the second experiment, orthotopic tumors were resected ten days after inoculation of tumor cells and tumor recurrence was measured following Infliximab treatment. Tumor progression was evaluated using 3D high resolution sonography.</p> <p>Results</p> <p>Sonography measurement of tumor volume in vivo showed inhibitory effect of Infliximab on primary tumor growth in both non-resected and resected models. Measurement of the dynamics of tumor growth by sonography revealed that in the primary tumor Infliximab is effective against established tumors while in the resection model, Infliximab is more effective at an early stage following tumor resection. Infliximab treatment is also effective in inhibiting tumor growth growth as a result of tumor cell contamination of the surgical field.</p> <p>Conclusions</p> <p>Clinical application of Infliximab is feasible in both the neoadjuvant and adjuvant setting. Infliximab is also effective in slowing the growth of tumor growth under the peritoneum and may have application in treating peritoneal carcinomatosis. Finally the study demonstrates that high resolution sonography is a sensitive imaging modality for the measurement of pancreatic tumor growth.</p

    Mechanisms controlling anaemia in Trypanosoma congolense infected mice.

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    Trypanosoma congolense are extracellular protozoan parasites of the blood stream of artiodactyls and are one of the main constraints on cattle production in Africa. In cattle, anaemia is the key feature of disease and persists after parasitaemia has declined to low or undetectable levels, but treatment to clear the parasites usually resolves the anaemia. The progress of anaemia after Trypanosoma congolense infection was followed in three mouse strains. Anaemia developed rapidly in all three strains until the peak of the first wave of parasitaemia. This was followed by a second phase, characterized by slower progress to severe anaemia in C57BL/6, by slow recovery in surviving A/J and a rapid recovery in BALB/c. There was no association between parasitaemia and severity of anaemia. Furthermore, functional T lymphocytes are not required for the induction of anaemia, since suppression of T cell activity with Cyclosporin A had neither an effect on the course of infection nor on anaemia. Expression of genes involved in erythropoiesis and iron metabolism was followed in spleen, liver and kidney tissues in the three strains of mice using microarrays. There was no evidence for a response to erythropoietin, consistent with anaemia of chronic disease, which is erythropoietin insensitive. However, the expression of transcription factors and genes involved in erythropoiesis and haemolysis did correlate with the expression of the inflammatory cytokines Il6 and Ifng. The innate immune response appears to be the major contributor to the inflammation associated with anaemia since suppression of T cells with CsA had no observable effect. Several transcription factors regulating haematopoiesis, Tal1, Gata1, Zfpm1 and Klf1 were expressed at consistently lower levels in C57BL/6 mice suggesting that these mice have a lower haematopoietic capacity and therefore less ability to recover from haemolysis induced anaemia after infection

    Late gadolinium uptake demonstrated with magnetic resonance in patients where automated PERFIT analysis of myocardial SPECT suggests irreversible perfusion defect

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    <p>Abstract</p> <p>Background</p> <p>Myocardial perfusion single photon emission computed tomography (MPS) is frequently used as the reference method for the determination of myocardial infarct size. PERFIT<sup>® </sup>is a software utilizing a three-dimensional gender specific, averaged heart model for the automatic evaluation of myocardial perfusion. The purpose of this study was to compare the perfusion defect size on MPS, assessed with PERFIT, with the hyperenhanced volume assessed by late gadolinium enhancement magnetic resonance imaging (LGE) and to relate their effect on the wall motion score index (WMSI) assessed with cine magnetic resonance imaging (cine-MRI) and echocardiography (echo).</p> <p>Methods</p> <p>LGE was performed in 40 patients where clinical MPS showed an irreversible uptake reduction suggesting a myocardial scar. Infarct volume, extent and major coronary supply were compared between MPS and LGE as well as the relationship between infarct size from both methods and WMSI.</p> <p>Results</p> <p>MPS showed a slightly larger infarct volume than LGE (MPS 29.6 ± 23.2 ml, LGE 22.1 ± 16.9 ml, p = 0.01), while no significant difference was found in infarct extent (MPS 11.7 ± 9.4%, LGE 13.0 ± 9.6%). The correlation coefficients between methods in respect to infarct size and infarct extent were 0.71 and 0.63 respectively. WMSI determined with cine-MRI correlated moderately with infarct volume and infarct extent (cine-MRI vs MPS volume r = 0.71, extent r = 0.71, cine-MRI vs LGE volume r = 0.62, extent r = 0.60). Similar results were achieved when wall motion was determined with echo. Both MPS and LGE showed the same major coronary supply to the infarct area in a majority of patients, Kappa = 0.84.</p> <p>Conclusion</p> <p>MPS and LGE agree moderately in the determination of infarct size in both absolute and relative terms, although infarct volume is slightly larger with MPS. The correlation between WMSI and infarct size is moderate.</p

    liver-enriched gene 1a and 1b Encode Novel Secretory Proteins Essential for Normal Liver Development in Zebrafish

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    liver-enriched gene 1 (leg1) is a liver-enriched gene in zebrafish and encodes a novel protein. Our preliminary data suggested that Leg1 is probably involved in early liver development. However, no detailed characterization of Leg1 has been reported thus far. We undertook both bioinformatic and experimental approaches to study leg1 gene structure and its role in early liver development. We found that Leg1 identifies a new conserved protein superfamily featured by the presence of domain of unknown function 781 (DUF781). There are two copies of leg1 in zebrafish, namely leg1a and leg1b. Both leg1a and leg1b are expressed in the larvae and adult liver with leg1a being the predominant form. Knockdown of Leg1a or Leg1b by their respective morpholinos specifically targeting their 5′-UTR each resulted in a small liver phenotype, demonstrating that both Leg1a and Leg1b are important for early liver development. Meanwhile, we found that injection of leg1-ATGMO, a morpholino which can simultaneously block the translation of Leg1a and Leg1b, caused not only a small liver phenotype but hypoplastic exocrine pancreas and intestinal tube as well. Further examination of leg1-ATGMO morphants with early endoderm markers and early hepatic markers revealed that although depletion of total Leg1 does not alter the hepatic and pancreatic fate of the endoderm cells, it leads to cell cycle arrest that results in growth retardation of liver, exocrine pancreas and intestine. Finally, we proved that Leg1 is a secretory protein. This intrigued us to propose that Leg1 might act as a novel secreted regulator that is essential for liver and other digestive organ development in zebrafish

    Integrating isotopes and documentary evidence : dietary patterns in a late medieval and early modern mining community, Sweden

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    We would like to thank the Archaeological Research Laboratory, Stockholm University, Sweden and the Tandem Laboratory (Ångström Laboratory), Uppsala University, Sweden, for undertaking the analyses of stable nitrogen and carbon isotopes in both human and animal collagen samples. Also, thanks to Elin Ahlin Sundman for providing the δ13C and δ15N values for animal references from Västerås. This research (Bäckström’s PhD employment at Lund University, Sweden) was supported by the Berit Wallenberg Foundation (BWS 2010.0176) and Jakob and Johan Söderberg’s foundation. The ‘Sala project’ (excavations and analyses) has been funded by Riksens Clenodium, Jernkontoret, Birgit and Gad Rausing’s Foundation, SAU’s Research Foundation, the Royal Physiographic Society of Lund, Berit Wallenbergs Foundation, Åke Wibergs Foundation, Lars Hiertas Memory, Helge Ax:son Johnson’s Foundation and The Royal Swedish Academy of Sciences.Peer reviewedPublisher PD

    Bayesian inference for the information gain model

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    One of the most popular paradigms to use for studying human reasoning involves the Wason card selection task. In this task, the participant is presented with four cards and a conditional rule (e.g., “If there is an A on one side of the card, there is always a 2 on the other side”). Participants are asked which cards should be turned to verify whether or not the rule holds. In this simple task, participants consistently provide answers that are incorrect according to formal logic. To account for these errors, several models have been proposed, one of the most prominent being the information gain model (Oaksford & Chater, Psychological Review, 101, 608–631, 1994). This model is based on the assumption that people independently select cards based on the expected information gain of turning a particular card. In this article, we present two estimation methods to fit the information gain model: a maximum likelihood procedure (programmed in R) and a Bayesian procedure (programmed in WinBUGS). We compare the two procedures and illustrate the flexibility of the Bayesian hierarchical procedure by applying it to data from a meta-analysis of the Wason task (Oaksford & Chater, Psychological Review, 101, 608–631, 1994). We also show that the goodness of fit of the information gain model can be assessed by inspecting the posterior predictives of the model. These Bayesian procedures make it easy to apply the information gain model to empirical data. Supplemental materials may be downloaded along with this article from www.springerlink.com
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