Effects of windblown dust on photovoltaic surface s on Mars

Photovoltaic (PV) coverslip material was subjected to Maritan dust storm conditions using basaltic dust flowing through the Martian Surface Wind Tunnel at NASA-Ames. Initially dusted and clear coverslips were held at angles from 0 to 90 deg., and the dust laden wind velocity was varied from 20 to 97 m/s. Blowing dust was found to adhere more to the coverslips as the angle was increased. However, dust was partially cleared from surfaces that were initially dusted at substantially lower velocities in dust laden wind than in clear wind. Thus, an equilibrium amount of dust accumulated which was dependent only upon angle and wind velocity and not upon initial concentration of dust. Abrasion was also evident in the coverslips. It increased with wind velocity and angle of attack. It appears that an initial dust layer may help to protect PV surfaces from abrasion

First thoracoscopic repair of tracheoesophageal fistula in the UAE: a case report and a review of the literature

Repair of esophageal atresia/tracheoesophageal fistula (EA/TEF) with open thoracotomy is associated with significant chest wall deformity. However, with the advancement made in minimally invasive instruments, thoracoscopic repair of this anomaly is achievable. We report our first successful case of thoracoscopic repair of EA/TEF. The surgical steps followed have been enumerated, as well as the postoperative management protocol. Thoracoscopic repair of EA/TEF is a real advantage for affected babies.Keywords: esophageal atresia, thoracoscopy, tracheoesophageal fistul

Foreign aid effectiveness in African economies: Evidence from a panel threshold framework

The aid-growth literature has been explored using a wide range of econometric methodologies. The evidence of the effectiveness of aid to promote economic growth is mixed, suggesting that the link between aid and growth is complex and may not be well identified by traditional methods. We take another perspective and frame the aid-growth literature within a nonlinear panel threshold framework applied to a panel of selected African economies for the period 1980 to 2007. We also compare our results with the linear and nonlinear-polynomial specification and address potential endogeneity using instrumental variables and dynamic panel estimations. In the linear setting, we find no clear evidence of a positive effect of aid on growth. In the nonlinear setting, we explore four threshold variables capturing various macroeconomic policies. For each threshold variable, we estimate a polynomial model by interacting aid with the considered threshold variable and a threshold model by splitting the sample according to some endogenous thresholds. Although we find no evidence of polynomial effect in the case of aid as a threshold variable, there is weak evidence of a threshold effect with a diminishing return of aid. In a lower regime of past aid receipts less than of 1.5 per cent of GDP, aid appears to have a strong positive and significant effect on growth while the effect is insignificant when aid exceeds that level. We also find that under good policy environment characterized by relatively low inflation, high trade openness and low budget deficit, the effect of aid is greater. These findings suggest that both donors and African aid recipient countries should continue their efforts in strengthening the macroeconomic management of aid

Non supersymmetric strong coupling background from the large N quantum mechanics of two matrices coupled via a Yang-Mills interaction

We derive the planar large N non-supersymmetric background of the quantum mechanical hamiltonian of two hermitean matrices coupled via a Yang-Mills interaction, in terms of the density of eigenvalues of one of the matrices. This background satisfies an implicit non linear integral equation, with a perturbative small coupling expansion and a solvable large coupling solution, which is obtained. The energy of system and the expectation value of several correlators are obtained in this strong coupling limit. They are free of infrared divergences.Comment: Latex, 13 page

Nutrient Sensing by Histone Marks: Reading the Metabolic Histone Code Using Tracing, Omics, and Modeling

Several metabolites serve as substrates for histone modifications and communicate changes in the metabolic environment to the epigenome. Technologies such as metabolomics and proteomics have allowed us to reconstruct the interactions between metabolic pathways and histones. These technologies have shed light on how nutrient availability can have a dramatic effect on various histone modifications. This metabolism–epigenome cross talk plays a fundamental role in development, immune function, and diseases like cancer. Yet, major challenges remain in understanding the interactions between cellular metabolism and the epigenome. How the levels and fluxes of various metabolites impact epigenetic marks is still unclear. Discussed herein are recent applications and the potential of systems biology methods such as flux tracing and metabolic modeling to address these challenges and to uncover new metabolic–epigenetic interactions. These systems approaches can ultimately help elucidate how nutrients shape the epigenome of microbes and mammalian cells.Histone post‐translational modifications (PTMs) sense cellular metabolic state and regulate gene expression, thereby influencing normal physiology and disease progression. While histone PTMs rely on metabolic substrates, how nutrients impact the histone PTM code is unclear. Here, systems biology technologies that can be used to study metabolic–epigenetic interactions are reviewed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156428/2/bies202000083_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156428/1/bies202000083.pd

Tingkat Kerentanan Sosial Ekonomi Petani terhadap Jatuhan Piroklastik Gunungapi (Kasus : Desa Ngargomulyo, Kecamatan Dukun, Kabupaten Magelang).

Penelitian dilakukan di Desa Ngargomulyo yang berada dalam kawasan berpotensi terlanda lontaran batu pijar dan hujan abu lebat. Tujuan dari penelitian ini adalah 1) Mengkaji tingkat kerentanan sosial ekonomi petani Desa Ngargomulyo dalam menghadapi ancaman jatuhan piroklastik Gunungapi Merapi; 2) Mengkaji upaya yang dilakukan oleh stakeholder kebencanaan untuk mengurangi kerentanan sosial-ekonomi petani. Metode analisis data dalam penelitian ini adalah analisis deskripitif kuantitatif untuk tujuan yang pertama dan deskiptif kualitatif untuk tujuan yang kedua.Hasil penelitian menunjukan bahwa 25 persen responden memiliki kerentanan sosial ekonomi tinggi, 47 persen memiliki kerentanan sedang dan 28 persen responden memiliki kerentanan rendah. Petani dengan dukungan aset natural yang lemah dan secara sosial kurang beruntung lebih rentan terhadap bahaya jatuhan piroklastik.Upaya yang dilakukan Pemerintah Desa Ngargomulyo dan rumah tangga tani adalah adanya inisasi konsep desa saudara dan tabungan ternak bencana. Peran LSM yang menonjol adalah peran LSM Save The Children dan Muslim Aid yang melakukan pendampingan kepada petani terkait dengan kegiatan pertanian serta kebencanaan

Stator Resistance Estimation Using Adaptive Estimation via a Bank of Kalman Filters

Accurate and efficient control of electric motors is dependent on knowledge of motor parameters such as the resistance and the inductance of the winding. However, these parameters are often unavailable to the control designer because they are dependent on the motor design and may change due to environmental effects such as temperature. An accurate real-time method to determine the values of these unknown parameters can improve motor performance over the entire operating range. In this work, a parameter estimation technique based on a bank of Kalman filters is used to adaptively estimate the motor winding resistance. Simulation results for a 3.5 horsepower interior permanent magnet (IPM) synchronous motor operating at rated torque demonstrate that this technique may be used for real-time estimation of motor parameters