Limiting current in a relativistic diode under the condition of magnetic insulation

The maximum emission current density is calculated for a time-independent, relativistic, cycloidal electron flow in a diode that is under the condition of magnetic insulation. Contrary to conventional thinking, this maximum current is not determined by the space charge limited condition on the cathode, even when the emission velocity of the electrons is assumed to be zero. The self electric and magnetic fields associated with the cycloidal flow are completely accounted for. This maximum current density is confirmed by a two-dimensional, fully electromagnetic and fully relativistic particle-in-cell code. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71144/2/PHPAEN-10-11-4489-1.pd

A new reference genome assembly for the microcrustacean Daphnia pulex

Comparing genomes of closely related genotypes from populations with distinct demographic histories can help reveal the impact of effective population size on genome evolution. For this purpose, we present a high quality genome assembly of Daphnia pulex (PA42), and compare this with the first sequenced genome of this species (TCO), which was derived from an isolate from a population with >90% reduction in nucleotide diversity. PA42 has numerous similarities to TCO at the gene level, with an average amino acid sequence identity of 98.8 and >60% of orthologous proteins identical. Nonetheless, there is a highly elevated number of genes in the TCO genome annotation, with similar to 7000 excess genes appearing to be false positives. This view is supported by the high GC content, lack of introns, and short length of these suspicious gene annotations. Consistent with the view that reduced effective population size can facilitate the accumulation of slightly deleterious genomic features, we observe more proliferation of transposable elements (TEs) and a higher frequency of gained introns in the TCO genome

Ambient-pressure molecular superconductor with a superlattice containing layers of tris(oxalato)rhodate enantiomers and 18-crown-6

We report a novel multilayered organic-inorganic hybrid material, β”-(BEDT-TTF)2[(H2O)(NH4)2Rh(C2O4)3].18-crown-6. This is the first molecular superconductor to have a superlattice with layers of both BEDT-TTF and 18-crown-6, and also the first with the anion tris(oxalato)rhodate. This is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is observed (β”). The strong 2D nature of this system strong-ly suggests that the superconducting transition is a KT transition. A superconducting Tc of 2.7 K at ambient pressure was found by transport and 2.5 K by magnetic susceptibility measurements

Exploring the Role of Mental Toughness in Bone Mineral Content: A Preliminary Study

Bone mineral content (BMC), a measure of the mineral content within a person’s bones, is an important parameter in the assessment of bone health. Changes in BMC can be indicative of bone-related conditions. Dual-energy X-ray absorptiometry (DXA) is one of the most widely used and accurate methods for measuring BMC. Sex, age, race, and BMI are known to influence BMC. Physical activity is positively related to BMC levels. Mental toughness (MT) is conceptualized as a state-like psychological resource conducive to goal-oriented pursuits and is positively linked to physical activity outcomes. The relationship between MT and BMC has not been explored. PURPOSE: To investigate the isolated effect of MT on BMC after eliminating the confounding effects of sex, age, race, and BMI. METHODS: A total of 95 individuals participated in the study across two study sites. The sample (Mage = 34.57, SD = 15.87) was predominantly White (64%), normal weight/overweight (MBMI = 25.96, SD = 4.88) males (54%). DXA scans were performed on calibrated scanners using standard procedures. MT was assessed via the Mental Toughness Index (MTI). To reduce measurement error, the MTI was administered twice, separated by a two-week interval. A linear regression model was used to analyze the relationship between BMC and the average of the two MTI scores, while controlling for sex, age, race, and BMI in MATLAB (R2023a). A Cohen’s d for MT and BMC was additionally conducted. RESULTS: The linear regression model was BMC ~ 1 + Sex + Age + Race + BMI + MT. The overall regression was statistically significant (R2 = 0.183, F(94, 88) = 2.78, p = .012). MT was found to significantly predict BMC (β = 0.093, p = .008, d = 2.7). CONCLUSION: The findings underscore the statistical significance of MT as a predictor of BMC, even when accounting for the influence of sex, age, race, and BMI. The effect size points to the practical significance of this relationship, suggesting that individuals with higher MT levels may exhibit greater BMC. Future investigations should consider incorporating demographic covariates to gain deeper insights into these relationships and conduct interventional studies to identify potential underlying mechanisms (e.g., how trainable MT could be linked, to some degree, with an increase in BMC)

Stereoisomeric semiconducting radical cation salts of chiral bis(2-hydroxypropylthio)ethylenedithioTTF with tetrafluoroborate anions

The new chiral TTF-based donor molecule bis(2-hydroxypropylthio)ethylenedithiotetrathiafulvalene has produced enantiopure R,R and S,S radical cation salts with the tetrafluoroborate anion as well as the nearly isostructural meso/racemate mixture. The enantiopure R,R or S,S salts are both 1:1 semiconducting salts with activation energies of 0.19–0.24 eV, both crystallising in the orthorhombic space group C2221. The semiconducting salt containing both meso and racemic donor cations has a very similar crystal structure but crystallising in the monoclinic space group C2/c (β = 91.39°) with similar S⋯S interactions but a smaller activation energy of 0.15–0.17 eV. This is in contrast to previous families of this type where the disordered racemate has a larger activation energy than its enantiopure salts

On the Detection of a Scalar Stochastic Background of Gravitational Waves

In the near future we will witness the coming to a full operational regime of laser interferometers and resonant mass detectors of spherical shape. In this work we study the sensitivity of pairs of such gravitational wave detectors to a scalar stochastic background of gravitational waves. Our computations are carried out both for minimal and non minimal coupling of the scalar fields.Comment: 25 pages, 3 figure

Measurement, modeling and simulation of photovoltaic degradation rates

Photovoltaic degradation rates play a vital role in visualizing and analyzing the performance of the PV modules over the long run. A site survey is conducted to calculate PV degradation rates. The results have shown that for the first three years since the initial installation, the degradation rates have remained in line with the manufacturer values (i.e., less than 0.6%), while the next two years the degradation rates have almost increased by 40%. This is due to discoloration of the encapsulant causing the reduction of the short circuit current (Isc). Mathematically, modeling such visual loss factors has not considered so far. The visual loss factor equation is developed and incorporated in the output current equation of the PV module. Further, the I-V curves are simulated and compared with the measured I-V curves. The results have shown an acceptable error percentage of around 0.3%

Radical-cation salt with novel BEDT-TTF packing motif containing tris(oxalato)germanate(IV)

The synthesis, crystal structure and resistivity of a new semiconducting BEDT-TTF radical-cation salt containing the tris(oxalato)germanate(IV) anion is reported. BEDT-TTF4[Ge(C2O4)3].0.5dichloromethane crystallizes in the space group P21/c, a = 18.322(7), b = 11.919(4), c = 32.746(11) Å, β = 105.797(5)°, V = 6881(4) Å3, T = 295(1) K, Z = 4. Electrical resistivity measurements show that BEDT-TTF4[Ge(C2O4)3].0.5dichloromethane is a semiconductor with an activation energy of 0.224 eV and room temperature resistivity of 212 Ω cm

Tubulin binding cofactor C (TBCC) suppresses tumor growth and enhances chemosensitivity in human breast cancer cells

<p>Abstract</p> <p>Background</p> <p>Microtubules are considered major therapeutic targets in patients with breast cancer. In spite of their essential role in biological functions including cell motility, cell division and intracellular transport, microtubules have not yet been considered as critical actors influencing tumor cell aggressivity. To evaluate the impact of microtubule mass and dynamics on the phenotype and sensitivity of breast cancer cells, we have targeted tubulin binding cofactor C (TBCC), a crucial protein for the proper folding of α and β tubulins into polymerization-competent tubulin heterodimers.</p> <p>Methods</p> <p>We developed variants of human breast cancer cells with increased content of TBCC. Analysis of proliferation, cell cycle distribution and mitotic durations were assayed to investigate the influence of TBCC on the cell phenotype. <it>In vivo </it>growth of tumors was monitored in mice xenografted with breast cancer cells. The microtubule dynamics and the different fractions of tubulins were studied by time-lapse microscopy and lysate fractionation, respectively. <it>In vitro </it>sensitivity to antimicrotubule agents was studied by flow cytometry. <it>In vivo </it>chemosensitivity was assayed by treatment of mice implanted with tumor cells.</p> <p>Results</p> <p>TBCC overexpression influenced tubulin fraction distribution, with higher content of nonpolymerizable tubulins and lower content of polymerizable dimers and microtubules. Microtubule dynamicity was reduced in cells overexpressing TBCC. Cell cycle distribution was altered in cells containing larger amounts of TBCC with higher percentage of cells in G2-M phase and lower percentage in S-phase, along with slower passage into mitosis. While increased content of TBCC had little effect on cell proliferation <it>in vitro</it>, we observed a significant delay in tumor growth with respect to controls when TBCC overexpressing cells were implanted as xenografts <it>in vivo</it>. TBCC overexpressing variants displayed enhanced sensitivity to antimicrotubule agents both <it>in vitro </it>and in xenografts.</p> <p>Conclusion</p> <p>These results underline the essential role of fine tuned regulation of tubulin content in tumor cells and the major impact of dysregulation of tubulin dimer content on tumor cell phenotype and response to chemotherapy. A better understanding of how the microtubule cytoskeleton is dysregulated in cancer cells would greatly contribute to a better understanding of tumor cell biology and characterisation of resistant phenotypes.</p