A Summation Formula for Estimating the Surface Areas of Ellipsoids

In this paper a summation formula for finding the surface area of general ellipsoids is derived.     

多孔压电线性理论中的唯一性定理、互易定理和特征值问题

假定弹性场和电场为正定,在多孔压电线性理论中建立起唯一性定理和互易定理．在准静态电场近似下,证明多孔压电材料线性理论中的一般性定理．利用弹性场的正定性,唯一性定理得到证明．在与多孔压电体自由振动相联系的特征值问题的研究中,给出了简明的公式．文中还研究了有关算子的某些特性．以简明公式为基础,利用变分法和算子法,研究了由于小扰动产生的频移问题．还给出了特殊情况下的扰动分析．     

Pressure broadened line widths of BrCN in the microwave region

The line widths of cyanogen bromide (BrCN) have been measured at room temperature (305 K) by using a double modulation microwave spectrograph. The self-broadening of two quadrupole hyperfine lines of the transition J = 3 → 4 has been measured. The foreign gas broadening by OCS, CO₂, N₂, CH₃CN, CH₃I, HCHO and CH₃CHO molecules has been measured only for the intense line at 32·957 GHz. These measured line widths have been compared with the calculated line widths using Anderson [6] as well as Murphy and Boggs [8] theories of pressure broadening.     

Towards a microchannel‐based X‐ray detector with two‐dimensional spatial and time resolution and high dynamic range

X‐ray detectors that combine two‐dimensional spatial resolution with a high time resolution are needed in numerous applications of synchrotron radiation. Most detectors with this combination of capabilities are based on semiconductor technology and are therefore limited in size. Furthermore, the time resolution is often realised through rapid time‐gating of the acquisition, followed by a slower readout. Here, a detector technology is realised based on relatively inexpensive microchannel plates that uses GHz waveform sampling for a millimeter‐scale spatial resolution and better than 100 ps time resolution. The technology is capable of continuous streaming of time‐ and location‐tagged events at rates greater than 10⁷ events per cm². Time‐gating can be used for improved dynamic range.     

The middleman as a panacea for supply chain coordination problems

The prevalence of intermediaries (middlemen) in supply chains is often seen as a dying remnant of less efficient times. Despite predictions that supply chains will rapidly “cut out the middleman” as technological advances have eased logistics, middlemen have continued to thrive. In this paper, we demonstrate a transaction role of middlemen that may help clarify their staying power. In a model with self-interested decision-making by both a manufacturer and a retailer, wherein incentive misalignment creates investment and production inefficiencies, we show that the integrated (first-best) outcome can be achieved with simple cost-based contracts if and only if a middleman is present. We further show that the approach of utilizing a middleman to fully coordinate the supply chain is robust in that it can be applied to a variety of circumstances discussed in the literature, including multilateral investment/effort choices, multiple product providers, and logistical investments made by the middleman.     

Effect of ovariectomy on contrast agent diffusion into lumbar intervertebral disc: a dynamic contrast-enhanced MRI study in female rats

Purpose

The purpose was to study the effect of estrogen deficiency on contrast agent diffusion into intervertebral disc in a rat model.

Materials and Methods

Seven-month-old female Sprague–Dawley rats were used. Fourteen rats had ovariectomy, and nine rats had sham surgery. Magnetic resonance imaging (MRI) of sagittal midsection of lumbar spine was performed with a 1.5-T magnet. Dynamic MRI was performed after a bolus injection of Gd-DOTA (0.3 mmol/kg) through tail vein. Eight hundred images were acquired at 0.6 s per acquisition. Regions of interests were drawn over three discs per rat. Maximum enhancement (E_max) and enhancement slope (E_slope) were evaluated. MRI was carried out at baseline and 8 weeks postsurgery.

Result

All disc enhancements demonstrated an initial fast wash-in phase followed by a second slower wash-in phase. For initial wash-in phase, E¹_max and E¹_slope of all rats remained unchanged at the two time points. For second wash-in phase, E²_max and E²_slope of control rats remained unchanged, while with ovariectomized rats, E²_max showed reduction at 8 weeks (4.5%±5.6%) compared to baseline (10.3%±6.3%, P=.037), and E²_slope was lower at 8 weeks (0.015±0.017) than the baseline (0.029±0.022), although it was not statistically significant (P=.101).

Conclusion

Ovariectomy induced detectable decrease in second wash-in phase of contrast agent into lumbar disc.     

Synthesis and applications of copillar[5]arene dithiols

Abstract

A novel copillar[4+1]arene incorporating alkylthiol substituents was synthesised in three steps and structurally characterised as the first example of a pillar[n]arene to incorporate two terminal thiols on the same aromatic ring. The macrocycle was attached to gold electrodes through a standard dipping technique. Cyclic voltammetry demonstrated selectivity for Li⁺ over other alkali metal cations. The copillar[4+1]arene was also used as a capping agent in the preparation of 3 nm gold nanoparticles.     

Phytocannabinoid Compositions from Cannabis Act Synergistically with PARP1 Inhibitor against Ovarian Cancer Cells In Vitro and Affect the Wnt Signaling Pathway

Ovarian cancer (OC) is the single most lethal gynecologic malignancy. Cannabis sativa is used to treat various medical conditions, and is cytotoxic to a variety of cancer types. We sought to examine the effectiveness of different combinations of cannabis compounds against OC. Cytotoxic activity was determined by XTT assay on HTB75 and HTB161 cell lines. Apoptosis was determined by flow cytometry. Gene expression was determined by quantitative PCR and protein localization by confocal microscopy. The two most active fractions, F5 and F7, from a high Δ9–tetrahydrocannabinol (THC) cannabis strain extract, and their standard mix (SM), showed cytotoxic activity against OC cells and induced cell apoptosis. The most effective phytocannabinoid combination was THC+cannabichromene (CBC)+cannabigerol (CBG). These fractions acted in synergy with niraparib, a PARP inhibitor, and were ~50-fold more cytotoxic to OC cells than to normal keratinocytes. The F7 and/or niraparib treatments altered Wnt pathway-related gene expression, epithelial–mesenchymal transition (EMT) phenotype and β-catenin cellular localization. The niraparib+F7 treatment was also effective on an OC patient’s cells. Given the fact that combinations of cannabis compounds and niraparib act in synergy and alter the Wnt signaling pathway, these phytocannabinoids should be examined as effective OC treatments in further pre-clinical studies and clinical trials.