GaInP-Leistungs-HBTs fuer Mobilkommunikation Abschlussbericht

SIGLEAvailable from TIB Hannover: F01B357+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Childbirth-related posttraumatic stress symptoms – examining associations with hair endocannabinoid concentrations during pregnancy and lifetime trauma

Abstract Evidence has linked alterations of the endocannabinoid system with trauma exposure and posttraumatic stress disorder (PTSD). Childbirth-related PTSD symptoms (CB-PTSS) affect about every eighth woman and can negatively influence the entire family. While aetiological models of CB-PTSD include psychological risk factors such as maternal trauma history and negative subjective birth experience (SBE), they lack biological risk indicators. We investigated whether lifetime trauma and CB-PTSS were associated with long-term endocannabinoid concentrations during pregnancy. Further, we tested endocannabinoids as mediators between lifetime trauma and CB-PTSS and whether SBE moderated such mediational paths. Within the prospective cohort study DREAMHAIR, 263 expectant mothers completed trauma assessments and provided hair samples for quantification of long-term endocannabinoid levels (anandamide [AEA], 2-arachidonoylglycerol [1-AG/2-AG], and N-acyl-ethanolamides [NAE]) prior to their anticipated birth date. Two months postpartum, CB-PTSS and SBE were measured. Regression models controlling for relevant confounders showed no association between lifetime trauma and hair endocannabinoids during pregnancy, yet higher number of lifetime trauma events and lower hair AEA were significantly associated with CB-PTSS, with the latter finding not remaining significant when Bonferroni corrections due to multiple testing were applied. While hair AEA did not mediate the association between lifetime trauma and CB-PTSS, the effect of lower hair AEA on CB-PTSS was stronger upon negative SBE. Results suggest greater lifetime trauma and reduced maternal hair AEA during pregnancy may be associated with increased risk for CB-PTSS, particularly upon negative SBE. Findings confirm lifetime trauma as a CB-PTSS risk factor and add important preliminary insights on the role of endocannabinoid ligand alterations and SBE in CB-PTSS pathology

GaAs microwave power HBTs for mobile communications

A I W output power (2.8 W/mm) GaAs-based HBT with more than 56 % power added efficiency at 3 V operating bias for use in mobile communications is described. Device layout and technology are optimized to obtain high microwave performance with low thermal resistance and compact chip size. The fabricated sub-cell power HBTs with 3x30 urn2 emitter area yield a maximum current gain of 90 with fmax > 100 GHz. The power cell HBT, which has 12x3x30 um2 emitter area exhibits 3 W (8.4 W/mm) output power and 70 % power added efficiency at VCE=8 V while maintaining high performance at low supply bias of 3 V

Technologie-Entwicklung fuer Kommunikationssysteme mit Arbeitsfrequenzen bis 30 GHz Abschlussbericht

The technology towards a stable 0.5 #mu#m GaAs-MESFET process has been developed and applied to different circuit concepts for communication systems up to 30 GHz. In detail, MMIC components for a 29 GHz transmitter and a 19 GHz receiver system such as low-noise, IF, and Power amplifiers, mixers and oscillators have been designed, processed and characterized. The interactive optimization of technology and circuit design led to monolithically integrated transmitter- and receiver moduls operating well according to the specifications. The technological contributions concerning epitaxy are concentrated to development of MESFET and (P)HEMT structures. Therefore a MOVPE equipment for the simultaneous epitaxy of five 3'' wafers has been installed and the corresponding processes have been developed accordingly. A good homogeneity regarding the material composition in heterostructures (#DELTA#x/x<#+-#1%), the layer thickness for doped and undoped structures (#DELTA#d/d<#+-#1%) and the sheet resistance (#DELTA#R_s/R_s<#+-#1.5%) have been obtained. Similar data are true concerning the reproducibility between individual batches. Regarding process technology a reproducible 0.5 #mu#m MESFET process has been developed. The parameter of this process has been kept constant after an initial stabilization phase in order to facilitate reproducible conditions for circuit design. In parallel to this standard process a more sophisticated 0.5 #mu#m process yielding better electrical and stability parameters has been developed which is now capable to replace the standard process. For the verification of the PHEMT structures grown by epitaxy a specially designed 0.3 #mu#m test process comprising T-gate structures enables RF-characterization of the PHEMT devices. This resulted in PHEMT structures showing the following microwave data: (transconductance #approx#500 mS/mm, f_T=60 GHz, f_m_a_x=90 GHz). (orig.)SIGLEAvailable from TIB Hannover: F96B1691+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

The effect of maternal childhood maltreatment on postpartum mother–child bonding and maternal hair glucocorticoids

Background: Maternal experiences of childhood maltreatment (CM) constitute a risk factor for impairments in the mother–child relationship. One mechanism underlying this intergenerational transmission may be maternal hypothalamic–pituitary–adrenal axis dysregulation. Yet, few studies have examined different maltreatment subtypes, including emotional neglect, considered concurrent depressive symptoms, and used long-term integrated glucocorticoid measures. Objective: This study aimed to investigate associations between maternal CM history, postpartum glucocorticoids in hair, and mother–child bonding. In exploratory analyses, we tested whether specific subtypes of CM had differential implications for glucocorticoid secretion and bonding. Methods: During pregnancy, N = 269 mothers from the prospective cohort study DREAMHAIR provided retrospective information on CM and current information regarding psychological and hair-related variables. Hair samples were collected 8 weeks after delivery for quantification of maternal long-term hair cortisol and cortisone concentrations in 2-cm scalp-near hair samples. Mother–child bonding was measured 8 weeks and 14 months after birth using the Postpartum Bonding Questionnaire. Results: While bivariate correlations revealed significant associations of CM with bonding and hair cortisol, regression findings showed CM was associated with impaired bonding 8 weeks (overall CM trend-level; emotional neglect p = .038) and 14 months (emotional neglect trend level p = .041) after birth, however not after controlling for depressive symptoms at the time point of the outcome. In regression analyses, CM was not associated with maternal hair glucocorticoids 8 weeks postpartum. Maternal hair glucocorticoid concentrations were not related to mother–child bonding and did not mediate associations between CM and mother–child bonding. Conclusion: Data tentatively suggest that mothers with CM experiences, in particular emotional neglect, may be at risk for suboptimal bonding to their child, however current depressive symptoms seem to be more important. Our data provide no evidence for a crucial role of glucocorticoid secretion, yet aetiological processes of long-term glucocorticoid secretion and bonding are complex and more severely affected samples should be examined. Maternal childhood maltreatment experiences, in particular emotional neglect, were associated with impaired mother–child bonding postpartum, however not after considering current depressive symptoms.While maternal childhood maltreatment correlated with maternal hair cortisol 8 weeks postpartum, this was not confirmed in regression analyses controlling for relevant confounders.Maternal hair glucocorticoid concentrations were not associated with impaired mother–child bonding. Maternal childhood maltreatment experiences, in particular emotional neglect, were associated with impaired mother–child bonding postpartum, however not after considering current depressive symptoms. While maternal childhood maltreatment correlated with maternal hair cortisol 8 weeks postpartum, this was not confirmed in regression analyses controlling for relevant confounders. Maternal hair glucocorticoid concentrations were not associated with impaired mother–child bonding.</p

Prozesskontrolle in der MOVPE mittels optischer in-situ-Analytik Abschlussbericht

The aim of the research work was the application of the spectroscopic methods Reflection-Anisotropy-Spectroscopy (RAS) an Ellipsometry (SE) for process control during growth of III-V-semiconductors by metalorganic vapour phase epitaxy (MOVPE). Sentech Instruments GmbH in cooperation with TU Berlin designed and built a demonstrator set-up of a robust and compact RAS-system. Meanwhile, this instrument was placed on the market as a new product (RAS 50). This set-up was successfully used at FBH for studies of process details like switching sequences and for on-line monitoring during production of device structures (LEDs und HBTs) by MOVPE. Further improvement of this RAS-set-up by TU Berlin for the first time made fully spectrally resolved RAS monitoring possible in a real production enviroment (wafer rotation). For the example of HBT layer structures it was shown that the reproducibility of the growth process can be assessed and deviations from the target process can be detected. Thus, control of the growth process was achieved. Real-time regulation of growth parameters for the correction of a deviation was demonstrated on the examples of lattice-matched growth of InGaAs on InP and InGaP on GaAs. The research work resulted in 41 scientific publications and 4 patents. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(65,29) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman