Magnetic Moments of the Baryon Decuplet in a Relativistic Quark Model

The magnetic moments of the baryon decuplet are calculated in a relativistic constituent quark model using the light-front formalism. Of particular interest are the magnetic moments of the $\Omega^-$ and $\Delta^{++}$ for which new recent experimental measurements are available. Our calculation for the magnetic moment ratio $\mu(\Delta^{++})/\mu(p)$ is in excellent agreement with the experimental ratio, while our ratio $\mu(\Omega^-)/\mu(\Lambda^0)$ is slightly higher than the experimental ratio.Comment: 10 pages ReVTeX, SLAC-PUB-621

Characterization of Defects and Designed Flaws in Metal Additive Manufacturing (AM) Parts with X-ray Computed Tomography (XCT)

Metal Additive Manufacturing (AM) has great potential to revolutionize manufacturing industries, but a reliable method to detect defects in AM-produced parts with complex internal structures must be developed prior to its widespread adoption. In this research, defects occurring in additively manufactured metal parts are characterized with X-ray Computed Tomography (XCT). In addition, the concept of metrological XCT is introduced, with the goal of providing more accurate dimensional measurements of the internal features. Preliminary experiments have been conducted toward the larger goal of evaluating XCT as a viable option for nondestructive evaluation of AM-produced components. Critical to this evaluation is the principle of the Probability of Detection (PoD), which has not been previously determined for typical AM defects using XCT. The first step in determining the PoD for XCT is to develop a suitable artifact with embedded features that are representative of the defects occurring in AM-produced parts. Two sets of samples were built by AM and their embedded defects measured by XCT. In the first set of samples, the chosen AM processing parameters were suboptimal, ensuring that defects would be present in the parts. These parameters were also varied to understand their effect on the resulting microstructure and defect formation. Measurements of porosity and the pore size distribution were determined from the XCT images. In the second set of samples, synthetic internal features were added, some approximating typical AM defects. Dimensional XCT was used to evaluate the quality of these features. Based on the results, a future experiment with the goal of estimating the PoD of critical AM defects with an XCT system is suggested

Accommodating false positives within acoustic spatial capture–recapture, with variable source levels, noisy bearings and an inhomogeneous spatial density

Funding: Tiago Marques was partly supported by CEAUL (funded by FCT - Fundação para a Ciência e a Tecnologia, Portugal, through the project UIDB/00006/2020).Passive acoustic monitoring is a promising method for surveying wildlife populations that are easier to detect acoustically than visually. When animal vocalisations can be uniquely identified on an array of sensors, the potential exists to estimate population density through acoustic spatial capture–recapture (ASCR). However, sound classification is imperfect, and in some situations, a high proportion of sounds detected on just a single sensor (‘singletons’) are not from the target species. We present a case study of bowhead whale calls (Baleana mysticetus) collected in the Beaufort Sea in 2010 containing such false positives. We propose a novel extension of ASCR that is robust to false positives by truncating singletons and conditioning on calls being detected by at least two sensors. We allow for individual-level detection heterogeneity through modelling a variable sound source level, model inhomogeneous call spatial density, and include bearings with varying measurement error. We show via simulation that the method produces near-unbiased estimates when correctly specified. Ignoring source-level variation resulted in a strong negative bias, while ignoring inhomogeneous density resulted in severe positive bias. The case study analysis indicated a band of higher call density approximately 30 km from shore; 59.8% of singletons were estimated to have been false positives.Publisher PDFPeer reviewe

Coulomb Drag for Strongly Localized Electrons: Pumping Mechanism

The mutual influence of two layers with strongly loclized electrons is exercised through the random Coulomb shifts of site energies in one layer caused by electron hops in the other layer. We trace how these shifts give rise to a voltage drop in the passive layer, when a current is passed through the active layer. We find that the microscopic origin of drag lies in the time correlations of the occupation numbers of the sites involved in a hop. These correlations are neglected within the conventional Miller-Abrahams scheme for calculating the hopping resistance.Comment: 5 pages, 3 figure

VaporSPOT: Parallel Synthesis of Oligosaccharides on Membranes

Automated chemical synthesis has revolutionized synthetic access to biopolymers in terms of simplicity and speed. While automated oligosaccharide synthesis has become faster and more versatile, the parallel synthesis of oligosaccharides is not yet possible. Here, a chemical vapor glycosylation strategy (VaporSPOT) is described that enables the simultaneous synthesis of oligosaccharides on a cellulose membrane solid support. Different linkers allow for flexible and straightforward cleavage, purification, and characterization of the target oligosaccharides. This method is the basis for the development of parallel automated glycan synthesis platforms

Complementary Patents and Market Structure

Many high technology goods are based on standards that require several essential patents owned by different IP holders. This gives rise to a complements and a double mark-up problem. We compare the welfare effects of two different business strategies dealing with these problems. Vertical integration of an IP holder and a downstream producer solves the double mark-up problem between these firms. Nevertheless, it may raise royalty rates and reduce output as compared to non-integration. Horizontal integration of IP holders solves the complements problem but not the double mark-up problem. Vertical integration discourages entry and reduces innovation incentives, while horizontal integration always benefits from entry and innovatio

Functional diversification of Argonautes in nematodes:an expanding universe

In the last decade, many diverse RNAi (RNA interference) pathways have been discovered that mediate gene silencing at epigenetic, transcriptional and post-transcriptional levels. The diversity of RNAi pathways is inherently linked to the evolution of Ago (Argonaute) proteins, the central protein component of RISCs (RNA-induced silencing complexes). An increasing number of diverse Agos have been identified in different species. The functions of most of these proteins are not yet known, but they are generally assumed to play roles in development, genome stability and/or protection against viruses. Recent research in the nematode Caenorhabditis elegans has expanded the breadth of RNAi functions to include transgenerational epigenetic memory and, possibly, environmental sensing. These functions are inherently linked to the production of secondary siRNAs (small interfering RNAs) that bind to members of a clade of WAGOs (worm-specific Agos). In the present article, we review briefly what is known about the evolution and function of Ago proteins in eukaryotes, including the expansion of WAGOs in nematodes. We postulate that the rapid evolution of WAGOs enables the exceptional functional plasticity of nematodes, including their capacity for parasitism

High-fidelity transmission of entanglement over a high-loss freespace channel

Quantum entanglement enables tasks not possible in classical physics. Many quantum communication protocols require the distribution of entangled states between distant parties. Here we experimentally demonstrate the successful transmission of an entangled photon pair over a 144 km free-space link. The received entangled states have excellent, noise-limited fidelity, even though they are exposed to extreme attenuation dominated by turbulent atmospheric effects. The total channel loss of 64 dB corresponds to the estimated attenuation regime for a two-photon satellite quantum communication scenario. We confirm that the received two-photon states are still highly entangled by violating the CHSH inequality by more than 5 standard deviations. From a fundamental point of view, our results show that the photons are virtually not subject to decoherence during their 0.5 ms long flight through air, which is encouraging for future world-wide quantum communication scenarios.Comment: 5 pages, 3 figures, replaced paper with published version, added journal referenc

The pathogenesis of trimethyltin chloride-induced nephrotoxicity

In exploratory studies aimed at elucidating CNS effects due to heavy metal toxicity, signs of compromised renal function were seen in rats. The studies reported here describe the sequential steps of the development of nephrotoxicity by trimethyltin chloride (TMT) in rats. Single doses of 12.25 mg/kg TMT administered orally to 150- to 175-g Long-Evans rats elicited overt signs of toxicity including behavioral abnormalities and marked weight loss. Concurrent with the development of these signs, nephrotoxicity was manifested as functional kidney compromise and associated histopathologic evidence of tubular damage. Pathological changes in the kidneys from treated rats were hyaline droplet inclusions, attenuated brush border, basolateral vacuolization, and eosinophilic granular casts in the proximal tubule cells. These lesions were detected as early as 2 days post-treatment and progressed with time in an orderly and sequential fashion. Renal lesions between 5 and 8 days were mild to severe cortical tubular dilatation, hydropic degeneration, and diffuse hyaline droplet deposition in the lower nephron tubules. Medullary edema and exfoliation of degenerated tubular epithelial cells with cast formation followed from 8 to 11 days. The morphological changes were accompanied by marked elevation of blood urea nitrogen, parallel with polyuria at Day 2 and oliguria by Day 14. Behavioral abnormalities as well as weight loss correlated well with the time course and severity of renal dysfunction and progression of morphological changes. A second experiment compared the effects of TMT in rats of different weights. Heavier rats were more sensitive than lighter rats to the nephrotoxic effects of TMT. These effects were independent of recognizable neurotoxic effects of TMT in the hippocampus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26824/1/0000383.pd

Defect-control of conventional and anomalous electron transport at complex oxide interfaces

Using low-temperature electrical measurements, the interrelation between electron transport, magnetic properties, and ionic defect structure in complex oxide interface systems is investigated, focusing on NdGaO3/SrTiO3 (100) interfaces. Field-dependent Hall characteristics (2–300 K) are obtained for samples grown at various growth pressures. In addition to multiple electron transport, interfacial magnetism is tracked exploiting the anomalous Hall effect (AHE). These two properties both contribute to a nonlinearity in the field dependence of the Hall resistance, with multiple carrier conduction evident below 30 K and AHE at temperatures ≲10  K. Considering these two sources of nonlinearity, we suggest a phenomenological model capturing the complex field dependence of the Hall characteristics in the low-temperature regime. Our model allows the extraction of the conventional transport parameters and a qualitative analysis of the magnetization. The electron mobility is found to decrease systematically with increasing growth pressure. This suggests dominant electron scattering by acceptor-type strontium vacancies incorporated during growth. The AHE scales with growth pressure. The most pronounced AHE is found at increased growth pressure and, thus, in the most defective, low-mobility samples, indicating a correlation between transport, magnetism, and cation defect concentratio