Application of Photovoltage Imaging to Semiconductor Wafer Characterization

A technique for imaging the distribution of ac surface photovoltages induced in a semiconductor wafer by the irradiation with a blue or near-infrared chopped photon beam is applied to non-destructive inspection of faults in Si or GaAs wafers. Faults detected include crystal defects, radiation damage, surface charge-up, striation and junction inhomogeneity. The principles of inspecting for the above mentioned wafer faults are quantitatively presented by numerical analyses of dependence of ac surface photovoltage on wafer electronic characteristics. The minimum detectable changes in minority carrier lifetime, interface trap density, fixed oxide charge density and resistivity for a depleted p-type Si wafer with a resistivity of 1Ωcm are estimated to be approximately 4%, 9%, 0.07% and 0.1%, respectively. For a weakly inverted wafer they are 4%, 250%, 1% and 4%, respectively. Examples of photovoltage images observed in Si wafers with swirl-like defects, grain boundaries, electron beam induced radiation damage. sulfate contamination and plasma induced surface charge up are shown together with images of an ion implanted GaAs wafer

Prdm5 Regulates Collagen Gene Transcription by Association with RNA Polymerase II in Developing Bone

PRDM family members are transcriptional regulators involved in tissue specific differentiation. PRDM5 has been reported to predominantly repress transcription, but a characterization of its molecular functions in a relevant biological context is lacking. We demonstrate here that Prdm5 is highly expressed in developing bones; and, by genome-wide mapping of Prdm5 occupancy in pre-osteoblastic cells, we uncover a novel and unique role for Prdm5 in targeting all mouse collagen genes as well as several SLRP proteoglycan genes. In particular, we show that Prdm5 controls both Collagen I transcription and fibrillogenesis by binding inside the Col1a1 gene body and maintaining RNA polymerase II occupancy. In vivo, Prdm5 loss results in delayed ossification involving a pronounced impairment in the assembly of fibrillar collagens. Collectively, our results define a novel role for Prdm5 in sustaining the transcriptional program necessary to the proper assembly of osteoblastic extracellular matrix

Regulation of Retinoid Receptors by Retinoic Acid and Axonal Contact in Schwann Cells

Background: Schwann cells (SCs) are the cell type responsible for the formation of the myelin sheath in the peripheral nervous system (PNS). As retinoic acid (RA) and other retinoids have a profound effect as regulators of the myelination program, we sought to investigate how their nuclear receptors levels were regulated in this cell type. Methodology/Principal Findings: In the present study, by using Schwann cells primary cultures from neonatal Wistar rat pups, as well as myelinating cocultures of Schwann cells with embryonic rat dorsal root ganglion sensory neurons, we have found that sustained expression of RXR-c depends on the continuous presence of a labile activator, while axonal contact mimickers produced an increase in RXR-c mRNA and protein levels, increment that could be prevented by RA. The upregulation by axonal contact mimickers and the transcriptional downregulation by RA were dependent on de novo protein synthesis and did not involve changes in mRNA stability. On the other hand, RAR-b mRNA levels were only slightly modulated by axonal contact mimickers, while RA produced a strong transcriptional upregulation that was independent of de novo protein synthesis without changes in mRNA stability. Conclusions/Significance: All together, our results show that retinoid receptors are regulated in a complex manner i

Starting Day Care in Espoo from the Viewpoint of Chinese Parents

The thesis is a small-scale evaluative research. The day care start folder, which provided practical and detailed information about starting Finnish day care to support multicultural parents in Otaniemi day-care centre and Servin-Maija day-care centre, was assessed among nine Chinese parents of children in five municipal and outsourced day-care centres in the City of Espoo. The purposes of the current research were to find out how Chinese parents perceive starting day care in the City of Espoo and their difficulties and suggestions concerning starting day care in the City of Espoo; to evaluate how the day care start folder is experienced as a working method in opinion of Chinese parents living in the City of Espoo; and to further improve the day care start folder as a working method for multicultural families and personnel in Otaniemi day-care centre and possibly for other day-care centres in the similar situation. Two types of interview, namely semi-structured individual interview and focus group interview, were utilised as the primary qualitative data-collecting methods in the current research. In addition, questionnaire as an assistant quantitative data-collecting method was employed as well to ensure verification of the consistency of the data, and supplement the abundance of the narrative data collected from interviews. The qualitative data gathered from the six interviews was coded, categorised and analysed in accordance with the method of content analysis. The results showed that the participating Chinese parents basically concerned about the information on starting day care; their child’s language learning; their communication and cooperation with day-care staff; cultures, religions and festivals; playing, learning and friends; child protection and legislation and so forth. Furthermore, these Chinese parents also put forward some important problems and suggestions on Finnish day care, such as problems caused by cultural differences, different opinions on learning by playing and Finnish as a second language-teaching, difficulties to obtain enough English information about Finnish day care, and the lack of mediums for foreign families to receive help concerning Finnish day care. In addition, these Chinese parents perceived the day care start folder as useful and adequate. The results based on the questionnaires supported and verified the results generated from the qualitative data analysis

Mice carrying a hypomorphic Evi1 allele are embryonic viable but exhibit severe congenital heart defects

The ecotropic viral integration site 1 (Evi1) oncogenic transcription factor is one of a number of alternative transcripts encoded by the Mds1 and Evi1 complex locus (Mecom). Overexpression of Evi1 has been observed in a number of myeloid disorders and is associated with poor patient survival. It is also amplified and/or overexpressed in many epithelial cancers including nasopharyngeal carcinoma, ovarian carcinoma, ependymomas, and lung and colorectal cancers. Two murine knockout models have also demonstrated Evi1's critical role in the maintenance of hematopoietic stem cell renewal with its absence resulting in the death of mutant embryos due to hematopoietic failure. Here we characterize a novel mouse model (designated Evi1(fl3)) in which Evi1 exon 3, which carries the ATG start, is flanked by loxP sites. Unexpectedly, we found that germline deletion of exon3 produces a hypomorphic allele due to the use of an alternative ATG start site located in exon 4, resulting in a minor Evi1 N-terminal truncation and a block in expression of the Mds1-Evi1 fusion transcript. Evi1(deltaex3/deltaex3) mutant embryos showed only a mild non-lethal hematopoietic phenotype and bone marrow failure was only observed in adult Vav-iCre/+, Evi1(fl3/fl3) mice in which exon 3 was specifically deleted in the hematopoietic system. Evi1(deltaex3/deltaex3) knockout pups are born in normal numbers but die during the perinatal period from congenital heart defects. Database searches identified 143 genes with similar mutant heart phenotypes as those observed in Evi1(deltaex3/deltaex3) mutant pups. Interestingly, 42 of these congenital heart defect genes contain known Evi1-binding sites, and expression of 18 of these genes are also effected by Evi1 siRNA knockdown. These results show a potential functional involvement of Evi1 target genes in heart development and indicate that Evi1 is part of a transcriptional program that regulates cardiac development in addition to the development of blood

Identification of molecular signatures specific for distinct cranial sensory ganglia in the developing chick

Background The cranial sensory ganglia represent populations of neurons with distinct functions, or sensory modalities. The production of individual ganglia from distinct neurogenic placodes with different developmental pathways provides a powerful model to investigate the acquisition of specific sensory modalities. To date there is a limited range of gene markers available to examine the molecular pathways underlying this process. Results Transcriptional profiles were generated for populations of differentiated neurons purified from distinct cranial sensory ganglia using microdissection in embryonic chicken followed by FAC-sorting and RNAseq. Whole transcriptome analysis confirmed the division into somato- versus viscerosensory neurons, with additional evidence for subdivision of the somatic class into general and special somatosensory neurons. Cross-comparison of distinct ganglia transcriptomes identified a total of 134 markers, 113 of which are novel, which can be used to distinguish trigeminal, vestibulo-acoustic and epibranchial neuronal populations. In situ hybridisation analysis provided validation for 20/26 tested markers, and showed related expression in the target region of the hindbrain in many cases. Results One hundred thirty-four high-confidence markers have been identified for placode-derived cranial sensory ganglia which can now be used to address the acquisition of specific cranial sensory modalities.</p