High frequency AC power and data distribution system

© Cranfield University 2011. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner.At present, power delivery issues are becoming a concern with modern state of the art electrical and electronic systems. The existing power networks, namely the centralized power architecture and the DC distributed power systems are struggling to cope with rigorous demands in some application areas. While active research to improve the current system is being relentlessly pursued, a more radical approach proposing a new power distribution system is increasingly drawing attention. High frequency AC (HFAC) power distribution architecture has been identified as a viable alternative to existing and future systems. The HFAC distributed power system (DPS) was initially proposed in the early 80s for space application and since then it has been considered for many modern ground based applications. This dissertation presents a fresh perspective to the problem by challenging the current notion of viewing the HFAC DPS merely as a passive power distribution system. The possibility of converting the existing system to a more intelligent architecture is investigated. Two fundamental features identified to be crucial for this implementation is the ability to communicate and to control power flow between the various power processing structures in the system. Developing the ♯enabling technologiesα is the primary focus of this research. A data modem designed to enable bidirectional multi node communication over the HFAC bus satisfies part of this requirement. The ability to control power flow is achieved by introducing digital control in the front end HFAC inverter. It is shown that intelligent management of the HFAC DPS offer potential efficiency benefits previously not possible in the traditional implementation. At the subsystem level, the front end inverter, the point of load (POL) converter and the communication module are investigated in depth. Extensive mathematical modelling is undertaken to develop optimal design guides to improve performance of the subsystems. Prototypes are constructed and the models are experimentally validated. In the case of the front end inverter, a multi stage inverter with parallel operation capability incorporating digital control is presented. An integral cycle converter is investigated as part of the POL subsystem and optimal synthesis pattern that improves power factor is identified. The communication subsystem constitutes the HFAC data modem described above. The modem emulates Ethernet style communication and interfaces to a host system via a simple serial communication link. All communication over the HFAC bus is performed transparently to the host. This dissertation contributes to the improvements of HFAC DPS at both the system and subsystem levels. At the system level, implementation of intelligent management of the HFAC DPS is shown to be viable and offers opportunities for improved performance and flexibility not previously possible. At the subsystem level, performance improvement to the individual power processing structures in the system is presented.Ph

Hepatitis B among Pacific Islanders in Southern California: how is health information associated with screening and vaccination?

We measured Hepatitis B virus (HBV) transmission knowledge and self-reported screening/testing behavior among Pacific Islanders (Guamanians/Chamorros, Samoans, and Tongans) in Southern California. We also examined access and trust by Pacific Islanders of varying health information sources. We administered and analyzed survey data (N = 297), using a convenience sample in Los Angeles, Orange, and San Diego Counties in spring 2009. We found that while Pacific Islander respondents reported that they receive health information from physicians, and largely trust this source, information from and trust in physicians were not statistically significant in explaining whether respondents sought HBV screening or vaccination

Clinical implications in the shift of syndecan-1 expression from the cell membrane to the cytoplasm in bladder cancer

Background To determine the diagnostic and prognostic capability of urinary and tumoral syndecan-1 (SDC-1) levels in patients with cancer of the urinary bladder. Methods SDC-1 levels were quantitated by enzyme-linked immunosorbent assay (ELISA) in 308 subjects (102 cancer subjects and 206 non-cancer subjects) to assess its diagnostic capabilities in voided urine. The performance of SDC-1 was evaluated using the area under the curve of a receiver operating characteristic curve. In addition, immunohistochemical (IHC) staining assessed SDC-1 protein expression in 193 bladder specimens (185 cancer subjects and 8 non-cancer subjects). Outcomes were correlated to SDC-1 levels. Results Mean urinary levels of SDC-1 did not differ between the cancer subjects and the non-cancer subjects, however, the mean urinary levels of SDC-1 were reduced in high-grade compared to low-grade disease (p < 0.0001), and in muscle invasive bladder cancer (MIBC) compared to non-muscle invasive bladder cancer (NMIBC) (p = 0.005). Correspondingly, preliminary data note a shift from a membranous cellular localization of SDC-1 in normal tissue, low-grade tumors and NMIBC, to a distinctly cytoplasmic localization in high-grade tumors and MIBC was observed in tissue specimens. Conclusion Alone urinary SDC-1 may not be a diagnostic biomarker for bladder cancer, but its urinary levels and cellular localization were associated with the differentiation status of patients with bladder tumors. Further studies are warranted to define the potential role for SDC-1 in bladder cancer progression

Internet Accessibility and Usage among Urban Adolescents in Southern California: Implications for Web-Based Health Research

The World Wide Web (WWW) poses a distinct capability to offer interventions tailored to the individual’s characteristics. To fine tune the tailoring process, studies are needed to explore how Internet accessibility and usage are related to demographic, psychosocial, behavioral, and other health related characteristics. This study was based on a cross-sectional survey conducted on 2373 7th grade students of various ethnic groups in Southern California. Measures of Internet use included Internet use at school or at home, Email use, chat-room use, and Internet favoring. Logistic regressions were conducted to assess the associations between Internet uses with selected demographic, psychosocial, behavioral variables and self-reported health statuses. The proportion of students who could access the Internet at school or home was 90% and 40%, separately. Nearly all (99%) of the respondents could access the Internet either at school or at home. Higher SES and Asian ethnicity were associated with higher internet use. Among those who could access the Internet and after adjusting for the selected demographic and psychosocial variables, depression was positively related with chat-room use and using the Internet longer than 1 hour per day at home, and hostility was positively related with Internet favoring (All ORs = 1.2 for +1 STD, p \u3c 0.05). Less parental monitoring and more unsupervised time were positively related to email use, chat-room use, and at home Internet use (ORs for +1 STD ranged from 1.2 to 2.0, all p \u3c 0.05), but not related to at school Internet use. Substance use was positively related to email use, chat-room use, and at home Internet use (OR for “used” vs. “not used” ranged from 1.2 to 4.0, p \u3c 0.05). Self-reported health problems were associated with higher levels of Internet use at home but lower levels of Internet use at school. More physical activity was related to more email use (OR = 1.3 for +1 STD), chat room use (OR = 1.2 for +1 STD), and at school ever Internet use (OR = 1.2 for +1 STD, all p \u3c 0.05). Body mass index was not related to any of the Internet use-related measures. In this ethnically diverse sample of Southern California 7th grade students, 99% could access the Internet at school and/or at home. This suggests that the Internet is already a potential venue for large scale health communication studies. Adolescents with more psychosocial risk factors or detrimental health behaviors were more likely to use the Internet. Therefore, if used properly, Internet interventions could effectively address the high risk populations. Additional research is needed to gain a more complete understanding of the positive and negative consequences of Internet use among adolescents

Investigation of CCL18 and A1AT as potential urinary biomarkers for bladder cancer detection

BACKGROUND: In this study, we further investigated the association of two biomarkers, CCL18 and A1AT, with bladder cancer (BCa) and evaluated the influence of potentially confounding factors in an experimental model. METHODS: In a cohort of 308 subjects (102 with BCa), urinary concentrations of CCL18 and A1AT were assessed by enzyme-linked immunosorbent assay (ELISA). In an experimental model, benign or cancerous cells, in addition to blood, were added to urines from healthy controls and analyzed by ELISA. Lastly, immunohistochemical staining for CCL18 and A1AT in human bladder tumors was performed. RESULTS: Median urinary protein concentrations of CCL18 (52.84 pg/ml vs. 11.13 pg/ml, p < 0.0001) and A1AT (606.4 ng/ml vs. 120.0 ng/ml, p < 0.0001) were significantly elevated in BCa subjects compared to controls. Furthermore, the addition of whole blood to pooled normal urine resulted in a significant increase in both CCL18 and A1AT. IHC staining of bladder tumors revealed CCL18 immunoreactivity in inflammatory cells only, and there was no significant increase in these immunoreactive cells within benign and cancerous tissue and no association with BCa grade nor stage was noted. A1AT immunoreactivity was observed in the cytoplasm of epithelia cells and intensity of immunostaining increased with tumor grade, but not tumor stage. CONCLUSIONS: Further development of A1AT as a diagnostic biomarker for BCa is warranted

New spinocerebellar ataxia subtype caused by SAMD9L mutation triggering mitochondrial dysregulation (SCA49)

Spinocerebellar ataxias consist of a highly heterogeneous group of inherited movement disorders clinically characterized by progressive cerebellar ataxia variably associated with additional distinctive clinical signs. The genetic heterogeneity is evidenced by the myriad of associated genes and underlying genetic defects identified. In this study, we describe a new spinocerebellar ataxia subtype in nine members of a Spanish five-generation family from Menorca with affected individuals variably presenting with ataxia, nystagmus, dysarthria, polyneuropathy, pyramidal signs, cerebellar atrophy and distinctive cerebral demyelination. Affected individuals presented with horizontal and vertical gaze-evoked nystagmus and hyperreflexia as initial clinical signs, and a variable age of onset ranging from 12 to 60 years. Neurophysiological studies showed moderate axonal sensory polyneuropathy with altered sympathetic skin response predominantly in the lower limbs. We identified the c.1877C > T (p.Ser626Leu) pathogenic variant within the SAMD9L gene as the disease causative genetic defect with a significant log-odds score (Z(max) = 3.43; theta = 0.00; P < 3.53 x 10(-5)). We demonstrate the mitochondrial location of human SAMD9L protein, and its decreased levels in patients' fibroblasts in addition to mitochondrial perturbations. Furthermore, mutant SAMD9L in zebrafish impaired mobility and vestibular/sensory functions. This study describes a novel spinocerebellar ataxia subtype caused by SAMD9L mutation, SCA49, which triggers mitochondrial alterations pointing to a role of SAMD9L in neurological motor and sensory functions. Corral-Juan et al. describe a novel dominantly inherited spinocerebellar ataxia subtype, SCA49, caused by SAMD9L mutation characterized by polyneuropathy, distinctive cerebral demyelination with gaze-evoked nystagmus and hyperreflexia as initial clinical signs. The study demonstrates the mitochondrial location of human SAMD9L protein triggering mitochondrial and lysosomal alterations

Low dose Btk inhibitors selectively block platelet activation by CLEC-2

Inhibitors of the tyrosine kinase Btk have been proposed as novel antiplatelet agents. In this study we show that low concentrations of the Btk inhibitor ibrutinib block CLEC-2-mediated activation and tyrosine phosphorylation including Syk and PLCγ2 in human platelets. Activation is also blocked in patients with X-linked agammaglobulinaemia (XLA) caused by a deficiency or absence of Btk. In contrast, the response to GPVI is delayed in the presence of low concentrations of ibrutinib or in patients with XLA, and tyrosine phosphorylation of Syk is preserved. A similar set of results is seen with the second-generation inhibitor, acalabrutinib. The differential effect of Btk inhibition in CLEC-2 relative to GPVI signalling is explained by the positive feedback role involving Btk itself, as well as ADP and thromboxane A2 mediated activation of P2Y12 and TP receptors, respectively. This feedback role is not seen in mouse platelets and, consistent with this, CLEC-2-mediated activation is blocked by high but not by low concentrations of ibrutinib. Nevertheless, thrombosis was absent in 8 out of 13 mice treated with ibrutinib. These results show that Btk inhibitors selectively block activation of human platelets by CLEC-2 relative to GPVI suggesting that they can be used at ‘low dose’ in patients to target CLEC-2 in thrombo-inflammatory disease