Summary of sand waves and regimes of flow in alluvial channels

CER60MLA24.Includes bibliographical references

Transport of sediment in helical corrugated pipe

CER57ARC9.Includes bibliographical references.Prepared for the February 18-22, 1957 meeting of the American Society of Civil Engineers in Jackson, Mississippi

Dynamic rotor mode in antiferromagnetic nanoparticles

We present experimental, numerical, and theoretical evidence for a new mode of antiferromagnetic dynamics in nanoparticles. Elastic neutron scattering experiments on 8 nm particles of hematite display a loss of diffraction intensity with temperature, the intensity vanishing around 150 K. However, the signal from inelastic neutron scattering remains above that temperature, indicating a magnetic system in constant motion. In addition, the precession frequency of the inelastic magnetic signal shows an increase above 100 K. Numerical Langevin simulations of spin dynamics reproduce all measured neutron data and reveal that thermally activated spin canting gives rise to a new type of coherent magnetic precession mode. This "rotor" mode can be seen as a high-temperature version of superparamagnetism and is driven by exchange interactions between the two magnetic sublattices. The frequency of the rotor mode behaves in fair agreement with a simple analytical model, based on a high temperature approximation of the generally accepted Hamiltonian of the system. The extracted model parameters, as the magnetic interaction and the axial anisotropy, are in excellent agreement with results from Mossbauer spectroscopy

Transcriptomic and epigenetic responses to short-term nutrient-exercise stress in humans

Abstract High fat feeding impairs skeletal muscle metabolic flexibility and induces insulin resistance, whereas exercise training exerts positive effects on substrate handling and improves insulin sensitivity. To identify the genomic mechanisms by which exercise ameliorates some of the deleterious effects of high fat feeding, we investigated the transcriptional and epigenetic response of human skeletal muscle to 9 days of a high-fat diet (HFD) alone (Sed-HFD) or in combination with resistance exercise (Ex-HFD), using genome-wide profiling of gene expression and DNA methylation. HFD markedly induced expression of immune and inflammatory genes, which was not attenuated by Ex. Conversely, Ex markedly remodelled expression of genes associated with muscle growth and structure. We detected marked DNA methylation changes following HFD alone and in combination with Ex. Among the genes that showed a significant association between DNA methylation and gene expression changes were PYGM, which was epigenetically regulated in both groups, and ANGPTL4, which was regulated only following Ex. In conclusion, while short-term Ex did not prevent a HFD-induced inflammatory response, it provoked a genomic response that may protect skeletal muscle from atrophy. These epigenetic adaptations provide mechanistic insight into the gene-specific regulation of inflammatory and metabolic processes in human skeletal muscle

A novel approach for adapting the standard addition method to single particle-ICP-MS for the accurate determination of NP size and number concentration in complex matrices; 35414390

This paper presents a novel approach, based on the standard addition method, for overcoming the matrix effects that often hamper the accurate characterization of nanoparticles (NPs) in complex samples via single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). In this approach, calibration of the particle size is performed by two different methods: (i) by spiking a suspension of NPs standards of known size containing the analyte, or (ii) by spiking the sample with ionic standards; either way, the measured sensitivity is used in combination with the transport efficiency (TE) for sizing the NPs. Moreover, such transport efficiency can be readily obtained from the data obtained via both calibration methods mentioned above, so that the particle number concentration can also be determined. The addition of both ionic and NP standards can be performed on-line, by using a T-piece with two inlet lines of different dimensions. The smaller of the two is used for the standards, thus ensuring a constant and minimal sample dilution. As a result of the spiking of the samples, mixed histograms including the signal of the sample and that of the standards are obtained. However, the use of signal deconvolution approaches permits to extract the information, even in cases of signal populations overlapping. For proofing the concept, characterization of a 50 nm AuNPs suspension prepared in three different media (i.e., deionized water, 5% ethanol, and 2.5% tetramethyl ammonium hydroxide-TMAH) was carried out. Accurate results were obtained in all cases, in spite of the matrix effects detected in some media. Overall, the approach proposed offers flexibility, so it can be adapted to different situations, but it might be specially indicated for samples for which the matrix is not fully known and/or dilution is not possible/recommended. © 2022 The Author

Resighting of a Narwhal (Monodon monoceros) Instrumented with a Satellite Transmitter

On 9 August 2001, a male narwhal (Monodon monoceros) was instrumented with a satellite transmitter attached to the dorsal side of the tusk in Creswell Bay on Somerset Island in the Canadian High Arctic. The whale was identified five years later, on 22 June 2006, in a photo of a group of narwhals taken from the ice edge in Lancaster Sound. Examination of the position of the transmitter on the tusk showed that the tusk had grown approximately 17 cm in the five-year period. The transmitter was still located on the dorsal side of the tusk and this fact, together with the length of spiral grains at the position of the tag, indicates that the tusk had not turned over (rotated) in the five-year period. The whale was photographed on its spring migration back to the original summer ground where it had been tagged. This resighting confirms evidence for site fidelity of narwhals, as the individual maintained the same migratory schedule and route observed for narwhals from previous satellite tracking studies in Creswell Bay.Le 9 août 2001, un émetteur satellite a été posé sur un narval mâle (Monodon monoceros), plus précisément du côté dorsal de sa défense et ce, dans la baie Creswell, à l’île Somerset, dans l’Extrême-Arctique canadien. Cinq ans plus tard, soit le 22 juin 2006, la baleine a été aperçue dans la photo d’un groupe de narvals prise à partir de la lisière de glaces du détroit de Lancaster. L’examen de l’emplacement de l’émetteur sur la défense a permis de constater que la défense avait grandi d’environ 17 cm pendant la période de cinq ans. L’émetteur se trouvait toujours du côté dorsal de la défense et cela, allié à la longueur des fibres torses à l’emplacement de l’étiquette, indique que la défense n’avait pas subi de rotation pendant la période de cinq ans. La baleine a été photographiée pendant sa migration printanière de retour vers l’endroit où elle avait d’abord été étiquetée l’été. Ce repérage permet de confirmer les preuves relativement à la fidélité des narvals à leurs emplacements, car cette baleine avait maintenu les mêmes horaire et trajet migratoires observés chez les narvals à partir d’autres études de repérage par satellite réalisées dans la baie Creswell

Magnetic anisotropy, first-order-like metamagnetic transitions and large negative magnetoresistance in the single crystal of Gd2_{2}PdSi3_3

Electrical resistivity ($\rho$), magnetoresistance (MR), magnetization, thermopower and Hall effect measurements on the single crystal Gd$_{2}$PdSi$_3$, crystallizing in an AlB$_2$-derived hexagonal structure are reported. The well-defined minimum in $\rho$ at a temperature above N\'eel temperature (T$_N$= 21 K) and large negative MR below $\sim$ 3T$_N$, reported earlier for the polycrystals, are reproducible even in single crystals. Such features are generally uncharacteristic of Gd alloys. In addition, we also found interesting features in other data, e.g., two-step first-order-like metamagnetic transitions for the magnetic field along [0001] direction. The alloy exhibits anisotropy in all these properties, though Gd is a S-state ion.Comment: RevTeX, 5 pages, 6 encapsulated postscript figures; scheduled to be published in Phy. Rev. B (01 November 1999, B1

Silka: A domestic technology to mediate the threshold between connection and solitude

Families living apart - with relatives and loved ones in different cities or countries - is not unusual. However, even though multiple communication technologies exist, communicating emotions can still be difficult. In this paper we present Silka: a device that supports long-distance communication by sending "smiles" and communicating presence in between traditional modes of communication, with the goal of enhancing bonds between two individuals or households. Silka's design is based on findings from an online survey, interviews and observations conducted to better understand how people communicate with loved ones and how they feel before and after communication. It aims to address worry and anxiety, which we found characterise the period between regular weekly, fortnightly or monthly calls. © 2012 Authors

Origin of entropy convergence in hydrophobic hydration and protein folding

An information theory model is used to construct a molecular explanation why hydrophobic solvation entropies measured in calorimetry of protein unfolding converge at a common temperature. The entropy convergence follows from the weak temperature dependence of occupancy fluctuations for molecular-scale volumes in water. The macroscopic expression of the contrasting entropic behavior between water and common organic solvents is the relative temperature insensitivity of the water isothermal compressibility. The information theory model provides a quantitative description of small molecule hydration and predicts a negative entropy at convergence. Interpretations of entropic contributions to protein folding should account for this result.Comment: Phys. Rev. Letts. (in press 1996), 3 pages, 3 figure

A cost for high levels of sperm competition in rodents: Increased sperm DNA fragmentation

Spermcompetition, a prevalent evolutionary process inwhich the spermatozoa of two or more males compete for the fertilization of the same ovum, leads to morphological and physiological adaptations, including increases in energetic metabolism that may serve to propel sperm faster but that may have negative effects onDNA integrity. SpermDNA damage is associated with reduced rates of fertilization, embryo and fetal loss, offspring mortality, and mutations leading to genetic disease. We tested whether high levels of sperm competition affect sperm DNA integrity. We evaluated sperm DNA integrity in 18 species of rodents that differ in their levels of spermcompetition using the spermchromatin structure assay. DNA integrity was assessed upon sperm collection, in response to incubation under capacitating or non-capacitating conditions, and after exposure to physical and chemical stressors. Sperm DNA was very resistant to physical and chemical stressors, whereas incubation in noncapacitating and capacitating conditions resulted in only a small increase in spermDNA damage. Importantly, levels of spermcompetition were positively associated with sperm DNA fragmentation across rodent species. This is the first evidence showing that high levels of sperm competition lead to an important cost in the form of increased sperm DNA damage.Peer Reviewe