Study of the island morphology at the early stages of Fe/Mo(110) MBE growth

We present theoretical study of morphology of Fe islands grown at Mo(110) surface in sub-monolayer MBE mode. We utilize atomistic SOS model with bond counting, and interactions of Fe adatom up to third nearest neighbors. We performed KMC simulations for different values of adatom interactions and varying temperatures. We have found that, while for the low temperature islands are fat fractals, for the temperature 500K islands have faceted rhombic-like shape. For the higher temperature, islands acquire a rounded shape. In order to evaluated qualitatively morphological changes, we measured averaged aspect ration of islands. We calculated dependence of the average aspect ratio on the temperature, and on the strength of interactions of an adatom with neighbors.Comment: 6 pages, 6 figures. Proceedings of 11-th Symposium on Surface Physics, Prague 200

The earliest evidence of Omophroninae (Coleoptera: Carabidae) from mid-Cretaceous Kachin amber and the description of a larva of a new genus

Omophroninae is a distinctive monogeneric group of Carabidae, presumably placed relatively close to the root of the megadiverse adephagan family. In the present study we describe a larva belonging to Omophroninae from mid-Cretaceous Burmese amber and erect a new genus †Cretomophron. Several features support the placement in this small but distinctive subfamily, such as the wedge-shaped head, the large triangular nasale, the elevated antennae with the apical segment directed sideways, the large and bidentate mandibular retinaculum, the enlarged hexagonal prothorax, legs with a distinct armature of spines, and the relatively narrow and posteriorly tapering abdomen. In contrast to larvae of the extant genus Omophron Latreille, the posterior tentorial grooves are not shifted backwards, apparently a plesiomorphic feature, the 2nd antennomeres are markedly longer, and the legs bear long setae and rather thin and long spike-like setae. †Cretomophron also differs in the presence of numerous setae arranged in transverse rows on abdominal segment VI. Lateral lobe-like expansions of abdominal tergites are a conspicuous feature of the new genus but similar structures occur in later instars of Omophron. Structural specializations of the head, prothorax and legs strongly suggest that the larvae were burrowing in sand, like adults and larvae of the extant genus, and that they were efficient predators, detecting prey with the unusually shaped antennae and long maxillae, grasping it with the elongate apical mandibular tooth, and squeezing and piercing it between the bidentate retinaculum and large and triangular nasale

Numerical Simulation of Table-Top Tunable Smith-Purcell Teraherz Free-Electron Laser Operating in the Superradiant Regime

Terahertz (THz) radiation occupies a very large portion of the electromagnetic spectrum and has generated much recent interest due to its ability to penetrate deep into many organic materials without the damage associated with ionizing radiation such as x-rays. One path for generating copious amount of tunable narrow-band THz radiation is based on the Smith-Purcell free-electron laser (SPFEL) effect. In this Letter we propose a simple concept for a compact tunable SPFEL operating in the superradiant regime and demonstrate its capabilities and performances via computer simulation using the conformal finite-difference time-domain electromagnetic solver VORPAL

Analysis of Adhesion Molecules and Basement Membrane Contributions to Synaptic Adhesion at the Drosophila Embryonic NMJ

Synapse formation and maintenance crucially underlie brain function in health and disease. Both processes are believed to depend on cell adhesion molecules (CAMs). Many different classes of CAMs localise to synapses, including cadherins, protocadherins, neuroligins, neurexins, integrins, and immunoglobulin adhesion proteins, and further contributions come from the extracellular matrix and its receptors. Most of these factors have been scrutinised by loss-of-function analyses in animal models. However, which adhesion factors establish the essential physical links across synaptic clefts and allow the assembly of synaptic machineries at the contact site in vivo is still unclear. To investigate these key questions, we have used the neuromuscular junction (NMJ) of Drosophila embryos as a genetically amenable model synapse. Our ultrastructural analyses of NMJs lacking different classes of CAMs revealed that loss of all neurexins, all classical cadherins or all glutamate receptors, as well as combinations between these or with a Laminin deficiency, failed to reveal structural phenotypes. These results are compatible with a view that these CAMs might have no structural role at this model synapse. However, we consider it far more likely that they operate in a redundant or well buffered context. We propose a model based on a multi-adaptor principle to explain this phenomenon. Furthermore, we report a new CAM-independent adhesion mechanism that involves the basement membranes (BM) covering neuromuscular terminals. Thus, motorneuronal terminals show strong partial detachment of the junction when BM-to-cell surface attachment is impaired by removing Laminin A, or when BMs lose their structural integrity upon loss of type IV collagens. We conclude that BMs are essential to tie embryonic motorneuronal terminals to the muscle surface, lending CAM-independent structural support to their adhesion. Therefore, future developmental studies of these synaptic junctions in Drosophila need to consider the important contribution made by BM-dependent mechanisms, in addition to CAM-dependent adhesion

Is there a role for CT coronary angiography in patients with symptomatic angina? Effect of coronary calcium score on identification of stenosis

Present guidelines discourage the use of CT coronary angiography (CTCA) in symptomatic angina patients. We examined the relation between coronary calcium score (CS) and the performance of CTCA in patients with stable and unstable angina in order to understand under which conditions CTCA might be a gate-keeper to conventional coronary angiography (CCA) in such patients. We included 360 patients between 50 and 70 years old with stable and unstable angina who were clinically referred for CCA irrespective of CS. Patients received CS and CCTA on 64-slice scanners in a multicenter cross-sectional trial. The institutional review board approved the study. Diagnostic performance of CTCA to detect or rule out significant coronary artery disease was calculated on a per patient level in pre-defined CS categories. The prevalence of significant coronary artery disease strongly increased with CS. Negative CTCA were associated with a negative likelihood ratio of <0.1 independent of CS. Positive CTCA was associated with a high positive likelihood ratio of 9.4 if CS was <10. However, for higher CS the positive likelihood ratio never exceeded 3.0 and for CS >400 it decreased to 1.3. In the 62 (17%) patients with CS <10, CTCA reliably identified the 42 (68%) of these patients without significant CAD, at no false negative CTCA scans. In symptomatic angina patients, a negative CTCA reliably excludes significant CAD but the additional value of CTCA decreases sharply with CS >10 and especially with CS >400. In patients with CS <10, CTCA provides excellent diagnostic performance

Dual-source computed tomography in patients with acute chest pain: feasibility and image quality

The aim of this study was to determine the feasibility and image quality of dual-source computed tomography angiography (DSCTA) in patients with acute chest pain for the assessment of the lung, thoracic aorta, and for pulmonary and coronary arteries. Sixty consecutive patients (32 female, 28 male, mean age 58.1±16.3 years) with acute chest pain underwent contrast-enhanced electrocardiography-gated DSCTA without prior beta-blocker administration. Vessel attenuation of different thoracic vascular territories was measured, and image quality was semi-quantitatively analyzed by two independent readers. Image quality of the thoracic aorta was diagnostic in all 60 patients, image quality of pulmonary arteries was diagnostic in 59, and image quality of coronary arteries was diagnostic in 58 patients. Pairwise intraindividual comparisons of attenuation values were small and ranged between 1±6 HU comparing right and left coronary artery and 56±9 HU comparing the pulmonary trunk and left ventricle. Mean attenuation was 291±65 HU in the ascending aorta, 334±93 HU in the pulmonary trunk, and 285±66 HU and 268±67 HU in the right and left coronary artery, respectively. DSCTA is feasible and provides diagnostic image quality of the thoracic aorta, pulmonary and coronary arteries in patients with acute chest pain

Digital chest radiography: an update on modern technology, dose containment and control of image quality

The introduction of digital radiography not only has revolutionized communication between radiologists and clinicians, but also has improved image quality and allowed for further reduction of patient exposure. However, digital radiography also poses risks, such as unnoticed increases in patient dose and suboptimum image processing that may lead to suppression of diagnostic information. Advanced processing techniques, such as temporal subtraction, dual-energy subtraction and computer-aided detection (CAD) will play an increasing role in the future and are all targeted to decrease the influence of distracting anatomic background structures and to ease the detection of focal and subtle lesions. This review summarizes the most recent technical developments with regard to new detector techniques, options for dose reduction and optimized image processing. It explains the meaning of the exposure indicator or the dose reference level as tools for the radiologist to control the dose. It also provides an overview over the multitude of studies conducted in recent years to evaluate the options of these new developments to realize the principle of ALARA. The focus of the review is hereby on adult applications, the relationship between dose and image quality and the differences between the various detector systems

Reduced Lung-Cancer Mortality with Volume CT Screening in a Randomized Trial

BACKGROUND There are limited data from randomized trials regarding whether volume-based, low-dose computed tomographic (CT) screening can reduce lung-cancer mortality among male former and current smokers. METHODS A total of 13,195 men (primary analysis) and 2594 women (subgroup analyses) between the ages of 50 and 74 were randomly assigned to undergo CT screening at T0 (baseline), year 1, year 3, and year 5.5 or no screening. We obtained data on cancer diagnosis and the date and cause of death through linkages with national registries in the Netherlands and Belgium, and a review committee confirmed lung cancer as the cause of death when possible. A minimum follow-up of 10 years until December 31, 2015, was completed for all participants. RESULTS Among men, the average adherence to CT screening was 90.0%. On average, 9.2% of the screened participants underwent at least one additional CT scan (initially indeterminate). The overall referral rate for suspicious nodules was 2.1%. At 10 years of follow-up, the incidence of lung cancer was 5.58 cases per 1000 personyears in the screening group and 4.91 cases per 1000 person-years in the control group; lung-cancer mortality was 2.50 deaths per 1000 person-years and 3.30 deaths per 1000 person-years, respectively. The cumulative rate ratio for death from lung cancer at 10 years was 0.76 (95% confidence interval [CI], 0.61 to 0.94; P = 0.01) in the screening group as compared with the control group, similar to the values at years 8 and 9. Among women, the rate ratio was 0.67 (95% CI, 0.38 to 1.14) at 10 years of follow-up, with values of 0.41 to 0.52 in years 7 through 9. CONCLUSIONS In this trial involving high-risk persons, lung-cancer mortality was significantly lower among those who underwent volume CT screening than among those who underwent no screening. There were low rates of follow-up procedures for results suggestive of lung cancer. (Funded by the Netherlands Organization of Health Research and Development and others; NELSON Netherlands Trial Register number, NL580.)