Statistical model of an undermoded reverberation chamber

Weibull distribution is adopted to model the electric field component of a Reverberation Chamber (RC). Its first property is to include the asymptotic laws, such as Rayleigh and exponential, and its main advantage lies in the fact that the Weibull shape parameter enables a model of the departure from overmoded to undermoded RC regime. Applications are given, such as an RC modal finite element modeling and a Monte Carlo simulation: they prove that the Weibull two-parameter distribution correctly models the quality factor influence. Moreover, the relevance of the use of this extreme value distribution is illustrated.     

High-Pressure Treatment and Freezing of Raw Goat Milk Curd for Cheese Manufacture: Effects on Cheese Characteristics

High-pressure treatment of raw goat milk curd was investigated as an alternative to thermal treatment of milk in cheese manufacture, and curd freezing as a procedure to surmount the seasonality of goat milk production. Experimental cheeses were made by mixing (70:30) fresh cow milk curd with frozen curd from pasteurized goat milk (PGC), frozen curd from raw goat milk (RGC), or frozen pressurized curd from raw goat milk (PRGC). Control cheese was made from a mixture (70:30) of pasteurized cow and goat milk. RGC cheese showed the highest counts of staphylococci, Gram-negative bacteria and coliforms, whereas PRGC cheese had maximum aminopeptidase activity, esterase activity, and overall proteolysis. Control cheese exhibited the highest dry matter content and peptide levels, the lowest concentration of free amino acids, the highest concentration of volatile compounds such as free fatty acids, alcohols and esters, and the firmest texture. Differences in sensory characteristics between experimental and control cheeses were of minor importance. High-pressure treatment of curd allowed the production of cheese of bacteriological quality similar to that of control cheese made using pasteurized milk, while curd freezing did not alter the sensory characteristics of experimental cheeses with respect to control cheese.     

铌和钛微合金化超级马氏体不锈钢在海水中点蚀机制的研究(英文)

超级马氏体不锈钢(SMSS)在较高温度下具有良好的力学性能,并具有高的应力腐蚀断裂抗力和良好的可焊性,因此其在苛刻环境下的应用正日趋广泛。用于石油勘探的材料要求其具有优良的综合性能,双相不锈钢和超级双相不锈钢尽管价格昂贵,但仍在该领域得到了广泛应用,而具有技术和经济优势的SMSS能取代上述两种钢在石油勘探领域获得应用。通常,SMSS在许多加工行业也有望得到应用。本文研究了添加与未添加Nb或Ti的SMSS的点蚀机制和形貌。添加Nb和Ti是为了使敏化的影响减至最小,促进晶粒细化,并研究其对钢在海水中点蚀的影响,重点在于点蚀的形貌和腐蚀电位。添加与未添加Nb和Ti的钢具有相近的显微硬度和类似的回火马氏体组织。阳极极化曲线表明,用Nb微合金化的钢的腐蚀电位高于其他钢。对不同电位下点蚀的形成和扩展进行了重复试验,并采用光学显微镜进行观察。在工业用钢中,添加Ti的钢显示出了最佳的耐蚀性能——具有最高的腐蚀电位和较低的点蚀电位。添加Nb的钢尽管腐蚀电位较高,但其点蚀电位比未添加Nb的钢低。     

A surrogate model to assess the whole body SAR induced by multiple plane waves at 2.4?GHz

The assessment of the exposure to electromagnetic waves is nowadays a key question. Dealing with the relationship between exposure and incident field, most of previous investigations have been performed with a single plane wave. Realistic exposure in the far field can be modeled as multiple plane waves with random direction of arrival, random amplitude, and random phase. This paper, based on numerical investigations, studies the whole body specific absorption rate (SAR) linked to the exposure induced by five random plane waves having uniformly distributed angles of arrival in the horizontal plane, log-normal distributed amplitudes, and uniformly distributed phases. A first result shows that this random heterogeneous exposure generates maximal variations of ??25% for the whole body specific absorption. An important observation is that the exposure to a single plane wave arriving face to the body, used for the guidelines, does not constitute the worst case. We propose a surrogate model to assess the distribution of the whole body SAR in the case of an exposure to multiple plane waves. For a sample of 30 values of whole body SAR induced by five plane waves at 2.4?GHz, this simple approach, considering the resulting SAR as the sum of the SAR induced by each isolated plane wave, leads to an estimated distribution of whole body SAR following the real distribution with a p value of 76% according to the Kolmogorov statistical test.     

Multiplex PCR/LDR for detection of K-ras mutations in primary colon tumors

The use of near-infrared spectroscopy to measure noninvasively changes in the redox state of cerebral cytochrome oxidase in vivo is controversial. We therefore tested these measurements using a multiwavelength detector in the neonatal pig brain. Exchange transfusion with perfluorocarbons revealed that the spectrum of cytochrome oxidase in the near-infrared was identical in the neonatal pig, the adult rat, and in the purified enzyme. Under normoxic conditions, the neonatal pig brain contained 15 micromol/L deoxyhemoglobin, 29 micromol/L oxyhemoglobin, and 1.2 micromol/L oxidized cytochrome oxidase. The mitochondrial inhibitor cyanide was used to determine whether redox changes in cytochrome oxidase could be detected in the presence of the larger cerebral hemoglobin concentration. Addition of cyanide induced full reduction of cytochrome oxidase in both blooded and bloodless animals. In the blooded animals, subsequent anoxia caused large changes in hemoglobin oxygenation and concentration but did not affect the cytochrome oxidase near-infrared signal. Simultaneous blood oxygenation level-dependent magnetic resonance imaging measurements showed a good correlation with near-infrared measurements of deoxyhemoglobin concentration. Possible interference in the near-infrared measurements from light scattering changes was discounted by simultaneous measurements of the optical pathlength using the cerebral water absorbance as a standard chromophore. We conclude that, under these conditions, near-infrared spectroscopy can accurately measure changes in the cerebral cytochrome oxidase redox state.     

Proteolysis, lipolysis, volatile compounds, texture, and flavor of Hispánico cheese made using frozen ewe milk curds pressed for different times

Hispánico cheese is manufactured in Spain from a mixture of cow and ewe milk. Production of ewe milk varies throughout the year, with a peak in spring and a valley in summer and autumn. To overcome this seasonal shortage, curd from spring ewe milk may be frozen and used for cheese manufacture some months later. In the present work, ewe milk curds pressed for 15, 60, or 120 min were held at −24°C for 4 mo, thawed, cut to 1-mm pieces, and mixed with fresh cow milk curd for the manufacture of experimental Hispánico cheeses. Control cheese was made from a mixture of pasteurized cow and ewe milk in the same (80:20) proportion. Cheeses, made in duplicate experiments, were analyzed throughout a 60-d ripening period. No significant differences between cheeses were found for lactic acid bacteria counts, dry matter content, hydrophilic peptides, 47 out of 68 vol.tile compounds, texture, and flavor characteristics. On the other hand, differences of minor practical significance between experimental and control cheeses, unrelated to the use of frozen ewe milk curd or the pressing time of ewe milk curd, were found for pH value, aminopeptidase activity, proteolysis, hydrophobic peptides, free amino acids, free fatty acids, and the remaining 21 vol.tile compounds. It may be concluded that the use of frozen ewe milk curd in the manufacture of Hispánico cheese does not alter its main characteristics.     

Architecture,Innovation and Tradition

Antoine Picon, Professor of the History of Architecture and Technology at Harvard Graduate School of Design (GSD), and the author of a significant new book, Ornament: The Politics of Architecture and Subjectivity (John Wiley & Sons), publishing in April 2013, provides the counterargument to this issue. He argues that for innovation to go beyond the superficial level of being a mere design trend or fashion, it needs to avoid ‘presentism’ and develop a reflexive stance to history and tradition.     

Fast and accurate calculation of scattered electromagnetic fields from building faces using Green?s functions of semi-infinite medium

A theoretical method based on the induction equivalence principle and Green's functions is presented here to calculate the scattered electromagnetic fields from exterior plane building facades in urban environment. The reflection coefficient of the whole inhomogeneous structure can be calculated for different incidence angles. The derivation of appropriate Green's functions is presented. The method takes into account the large-scale discontinuities on the facade. It is simple to implement and fast to obtain results because of the absence of poles in the Green's functions expressions. The accuracy of the method is discussed comparing to a commercial software and physical optics as another method based on equivalent currents. The article concludes with a statistical study on the influence of concrete permittivity variation on the reflection coefficient of a concrete'glass building facade.     

Using High-Pressure Processing for Reduction of Proteolysis and Prevention of Over-ripening of Raw Milk Cheese

High-pressure-processing (HPP) at 400 or 600 MPa was applied to cheeses made from ewe raw milk, on days 21 or 35 after manufacturing, to reduce proteolysis and prevent over-ripening. The characteristics of HPP and non-pressurized (control) cheeses were compared during ripening at 8 °C until day 60 and further storage at 4 °C until day 240. HPP and control cheeses showed similar pH values throughout ripening, but on day 240 pH values remained 0.4–0.6 units lower for HPP cheeses than for the control cheeses. Casein degradation was significantly retarded in the 600 MPa cheeses. Their α-casein concentration was 48–52 % higher on day 60 and 30–33 % higher on day 240 than in the control cheeses while β-casein concentration was 25–26 % higher on day 60 and 100–103 % higher on day 240. No significant differences in para-κ-casein concentration between cheeses were found on day 60, but on day 240, it was 22–35 % higher in the 600 MPa cheeses than in the control cheese. Hydrophilic peptides, hydrophobic peptides and total free amino acids evolved similarly in HPP and control cheeses during the 60-day ripening period. However, on day 240 hydrophilic peptides were at 34–39 % lower levels in the 600 MPa cheeses than in the control cheeses, hydrophobic peptides at 7–16 % lower levels and total free amino acids at 25–29 % lower levels. Flavour intensity scores increased at a slower rate in HPP cheeses than in the control cheese. Flavour quality declined markedly in the control cheeses during refrigerated storage while it did not vary significantly in 600 MPa cheeses.