Substance-to-substance joining of quartz glass

Abstract. A pioneering procedure for substance-to-substance joining of quartz glass is described. Diffusion welding was examined as a possible joining method. Welded components made of quartz glass are applied in high-temperature engineering for laser and optics applications. Quartz glass was joined without interlayers in order to maintain optical characteristics of the joining partners. Based on the principles of joint formation of pure SiO2-glass in the solid state, a joining technology, using diffusion welding, is described and the joints are analysed. Diffusion welding, realized at near-transformation temperature, results in an increase of polymerization and formation of an optical thin joining layer. Key words: quartz glass, diffusion welding, thermal expansion, substance-to-substance joint

A crucial role for the ubiquitously expressed transcription factor Sp1 at early stages of hematopoietic specification

Mammalian development is regulated by the interplay of tissue-specific and ubiquitously expressed transcription factors, such as Sp1. Sp1 knockout mice die in utero with multiple phenotypic aberrations, but the underlying molecular mechanism of this differentiation failure has been elusive. Here, we have used conditional knockout mice as well as the differentiation of mouse ES cells as a model with which to address this issue. To this end, we examine

Ethnic Minority–Majority Unions in Estonia

Ethnic minority–majority unions—also referred to as mixed ethnic unions—are often seen as the ultimate evidence of the integration of ethnic minorities into their host societies. We investigated minority–majority unions in Estonia, where ethnic minorities account for one-third of the total population (Russians 26%, followed by Ukrainians, Byelorussians, Finns and other smaller groups). Using data from the 2000 Estonian census and regression models, we found that Slavic women are less likely to be in minority–majority unions than are members of other minority groups, with Russians being the least likely. Finns, who are culturally most similar to the Estonian majority population, are the most likely to form a union with an Estonian. For ethnic minority women, the likelihood of being in minority–majority unions is highest in rural areas and increases over generations, with third-generation immigrants being the most likely. Estonian women are most likely to have a minority partner when they or their parents were born abroad and when they live in urban areas. Our findings suggest that both the opportunity to meet potential partners and openness to other ethnic groups are important factors for understanding the dynamics of minority–majority unions

A crucial role for the ubiquitously expressed transcription factor Sp1 at early stages of hematopoietic specification.

Mammalian development is regulated by the interplay of tissue-specific and ubiquitously expressed transcription factors, such as Sp1. Sp1 knockout mice die in utero with multiple phenotypic aberrations, but the underlying molecular mechanism of this differentiation failure has been elusive. Here, we have used conditional knockout mice as well as the differentiation of mouse ES cells as a model with which to address this issue. To this end, we examined differentiation potential, global gene expression patterns and Sp1 target regions in Sp1 wild-type and Sp1-deficient cells representing different stages of hematopoiesis. Sp1(-/-) cells progress through most embryonic stages of blood cell development but cannot complete terminal differentiation. This failure to fully differentiate is not seen when Sp1 is knocked out at later developmental stages. For most Sp1 target and non-target genes, gene expression is unaffected by Sp1 inactivation. However, Cdx genes and multiple Hox genes are stage-specific targets of Sp1 and are downregulated at an early stage. As a consequence, expression of genes involved in hematopoietic specification is progressively deregulated. Our work demonstrates that the early absence of active Sp1 sets a cascade in motion that culminates in a failure of terminal hematopoietic differentiation and emphasizes the role of ubiquitously expressed transcription factors for tissue-specific gene regulation. In addition, our global side-by-side analysis of the response of the transcriptional network to perturbation sheds a new light on the regulatory hierarchy of hematopoietic specification

Mixed Marriages in Germany:A High Risk of Divorce for Immigrant-Native Couples

This study investigates the effect of native/immigrant intermarriage on divorce. We used a rich longitudinal dataset from the German Socio-Economic Panel and applied event-history techniques to examine the risk of divorce among immigrants in Germany. Our analysis of the divorce rates of 5,648 marriages shows that immigrant couples have a lower risk of divorce than do natives. However, marriages between German-born individuals and immigrants have a higher likelihood of separation than marriages between two German-born individuals or between immigrants from the same country, supporting the exogamy hypothesis. This pattern largely persists when controlling for the socio-demographic and human-capital characteristics of the spouses. The divorce risk increases with the cultural distance between the partners and when the spouses demonstrate differences in their social backgrounds, also supporting the heterogamy hypothesis and the selectivity hypothesis. We found no support for the adaptation and convergence hypotheses. Divorce levels for mixed marriages are neither similar to the levels of one of the constituent origin groups, nor do they fall between the levels of the two groups; the divorce levels for native/immigrant marriages are higher than those for endogamous marriages.</p

Robotic total pancreatectomy with splenectomy: technique and outcomes

BACKGROUND:Robotic total pancreatectomy (TP) represents a minimally invasive approach to a major intra-abdominal operation. Its utility, technique, and outcomes are evolving. METHODS:In this video, we describe a systematic approach to a robotic total pancreatectomy performed for multifocal intraductal papillary mucinous neoplasm (IPMN). Additionally, we reviewed the National Cancer Database (NCDB) to examine the outcomes of robotic TP compared to laparoscopic and open TP between 2010 and 2014. RESULTS:The patient is a 61-year-old female who was diagnosed with multifocal IPMN. A total of 6 robotic ports were placed and the da Vinci Xi robotic system was used with the patient supine. The approach entailed as follows: (1) Diagnostic laparoscopy; (2) Entry into the lesser sac; (3) Division of the short gastric vessels; (4) Exposure and dissection of the inferior pancreas border; (5) Dissection and transection of the splenic artery; (6) Mobilization of the pancreas tail/spleen; (7) Exposure of the splenic vein-superior mesenteric vein confluence; (8) Kocher maneuver; (9) Release of the ligament of Treitz and transection of the proximal jejunum; (10) Transection of the distal stomach; (11) Portal lymphadenectomy; (12) Dissection and transection of the gastroduodenal artery; (13) Superior mesenteric vein exposure/dissection of the uncinate process; (14) Hepaticojejunostomy; (15) Cholecystectomy; and (16) Gastrojejunostomy. NCDB database review of 73 patients who underwent robotic TP revealed similar rates of margin negative resections and retrieved lymph nodes between robotic, laparoscopic, and open TP, whereas robotic and laparoscopic TP were associated with shorter in-hospital stay and reduced mortality at 30 and 90&nbsp;days compared to open TP. Overall median survival of pancreatic adenocarcinoma patients who underwent TP was similar between robotic, laparoscopic, and open approaches. CONCLUSION:Robotic total pancreatectomy with splenectomy offers a minimally invasive approach to a major abdominal operation and is feasible in a stepwise, reproducible technique. It is associated with improved postoperative outcomes and equivalent oncologic outcomes compared to open TP

A Compact Lowpass Filter with Ultra Wide Stopband using Stepped Impedance Resonator

In this paper, a compact asymmetric-shaped microstrip lowpass filter (LPF) using a stepped impedance resonator is presented. An ultra wide stopband with high attenuation in the stopband region, within very small circuit area is achieved for the proposed filter using novel asymmetric structures for resonator and suppressor. The transmission zeros of the resonators can be adjusted as a function of high impedance and low impedance microstrip lines, and due to the asymmetric structure, the proposed suppressing cell can be located within the resonator structure without occupying a large area. For verification, a 2.92 GHz LPF is designed and fabricated. The experimental results, in comparison with the other LPFs, show that the proposed LPF has significant advantages in the stopband characteristics with acceptable sharp roll off. The measured passband insertion loss is below 0.1 dB, and the rejection band over -20 dB is obtained from 3.42 GHz to 36.2 GHz. The size of filter corresponds to compact electrical size of 0.156 λg × 0.128 λg, where λg is the guided wavelength at 2.92 GHz. Also, the maximum variation of the group delay in 80 percent of the passband region is only about 0.2 ns