The organization and administration of the foreign service of the United States

Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive

Fabrication of elastomeric stamps with polymer-reinforced sidewalls via chemically selective vapor deposition polymerization of poly(p-xylylene)

We report on the preparation of polydimethylsiloxane stamps with selectively grown polymer sidewalls by chemical vapor deposition polymerization of poly(ppoly(p-xylylene). Using a thin iron layer as an inhibitor, the deposition occurs only on the sidewalls of the features in relief, resulting in a polymer-reinforced stamp. The wetting properties of stamps can be restored after removing the thin iron layer with an acidic solution, which has been verified by pattern transfer to an underlying substrate using molding and microcontact printing. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69846/2/APPLAB-83-20-4250-1.pd

Chromatin remodeling protein HELLS is critical for retinoblastoma tumor initiation and progression.

Retinoblastoma is an aggressive childhood cancer of the developing retina that initiates by biallelic RB1 gene inactivation. Tumor progression in retinoblastoma is driven by epigenetics, as retinoblastoma genomes are stable, but the mechanism(s) that drive these epigenetic changes remain unknown. Lymphoid-specific helicase (HELLS) protein is an epigenetic modifier directly regulated by the RB/E2F pathway. In this study, we used novel genetically engineered mouse models to investigate the role of HELLS during retinal development and tumorigenesis. Our results indicate that Hells-null retinal progenitor cells divide, undergo cell-fate specification, and give rise to fully laminated retinae with minor bipolar cells defects, but normal retinal function. Despite the apparent nonessential role of HELLS in retinal development, failure to transcriptionally repress Hells during retinal terminal differentiation due to retinoblastoma (RB) family loss significantly contributes to retinal tumorigenesis. Loss of HELLS drastically reduced ectopic division of differentiating cells in Rb1/p107-null retinae, significantly decreased the incidence of retinoblastoma, delayed tumor progression, and increased overall survival. Despite its role in heterochromatin formation, we found no evidence that Hells loss directly affected chromatin accessibility in the retina but functioned as transcriptional co-activator of E2F3, decreasing expression of cell cycle genes. We propose that HELLS is a critical downstream mediator of E2F-dependent ectopic proliferation in RB-null retinae. Together with the nontoxic effect of HELLS loss in the developing retina, our results suggest that HELLS and its downstream pathways could serve as potential therapeutic targets for retinoblastoma

Modeling Capacity-related Factors in a Theme Park Context

A comprehensive analysis among theme park capacity and all its factors is lacked in existing tourism research. Based on a case study of a Chinese theme park, this paper explores the factors that affect theme park’s capacity and the relationships among them. Two models on theme park attendance-related factors and experience-related factors were built based on empirical tests and previous studies. Attendance, waiting time and tourist satisfaction were found to be closely related to each other. Tolerable waiting time, visitors’ expectation on the number and experience value of attractions visited can be effective indicators used to determine appropriate capacity of theme park. In the end, this paper conceptualized a comprehensive model of the relationships among theme park attendance, capacity, visitor waiting time, expectation on experience, satisfaction, and other related variables, based on the research findings and literature review

Technical efficiency of small-scale honey producers in Ethiopia: A stochastic frontier analysis

In this paper, a study is presented of the dynamic behavior of an automatic transmit power control (ATPC) loop in a single fixed wireless system (FWS) link subject to multipath fading and an uncorrelated co-channel interferer that does not use ATPC (this represents a so-called non-ATPC FWS link or a fixed satellite link). Fundamental questions include the sensitivity of an ATPC link to multipath interference and the co-channel interference that may be caused by a non-ATPC interferer. In the context of the present project, a good example of a non-ATPC interferer is a fixed satellite to which one antenna in a fixed microwave link has partial view. A computer model was developed that constitutes a useful tool in describing; simulating and analyzing an ATPC loop in a single FWS link. With the aid of this model, results are presented on the sensitivity of an ATPC loop in a FWS link with respect to channel conditions, non-ATPC interference and parameter settings

Validation of a Predictive Model for Survival in Patients With Advanced Cancer: Secondary Analysis of RTOG 9714.

BackgroundThe objective of this study was to validate a simple predictive model for survival of patients with advanced cancer.MethodsPrevious studies with training and validation datasets developed a model predicting survival of patients referred for palliative radiotherapy using three readily available factors: primary cancer site, site of metastases and Karnofsky performance score (KPS). This predictive model was used in the current study, where each factor was assigned a value proportional to its prognostic weight and the sum of the weighted scores for each patient was survival prediction score (SPS). Patients were also classified according to their number of risk factors (NRF). Three risk groups were established. The Radiation Therapy and Oncology Group (RTOG) 9714 data was used to provide an additional external validation set comprised of patients treated among multiple institutions with appropriate statistical tests.ResultsThe RTOG external validation set comprised of 908 patients treated at 66 different radiation facilities from 1998 to 2002. The SPS method classified all patients into the low-risk group. Based on the NRF, two distinct risk groups with significantly different survival estimates were identified. The ability to predict survival was similar to that of the training and previous validation datasets for both the SPS and NRF methods.ConclusionsThe three variable NRF model is preferred because of its relative simplicity

Magnetic Resonance Imaging of Optic Nerve Traction During Adduction in Primary Open-Angle Glaucoma With Normal Intraocular Pressure.

PurposeWe used magnetic resonance imaging (MRI) to ascertain effects of optic nerve (ON) traction in adduction, a phenomenon proposed as neuropathic in primary open-angle glaucoma (POAG).MethodsSeventeen patients with POAG and maximal IOP ≤ 20 mm Hg, and 31 controls underwent MRI in central gaze and 20° to 30° abduction and adduction. Optic nerve and sheath area centroids permitted computation of midorbital lengths versus minimum paths.ResultsAverage mean deviation (±SEM) was -8.2 ± 1.2 dB in the 15 patients with POAG having interpretable perimetry. In central gaze, ON path length in POAG was significantly more redundant (104.5 ± 0.4% of geometric minimum) than in controls (102.9 ± 0.4%, P = 2.96 × 10-4). In both groups the ON became significantly straighter in adduction (28.6 ± 0.8° in POAG, 26.8 ± 1.1° in controls) than central gaze and abduction. In adduction, the ON in POAG straightened to 102.0% ± 0.2% of minimum path length versus 104.5% ± 0.4% in central gaze (P = 5.7 × 10-7), compared with controls who straightened to 101.6% ± 0.1% from 102.9% ± 0.3% in central gaze (P = 8.7 × 10-6); and globes retracted 0.73 ± 0.09 mm in POAG, but only 0.07 ± 0.08 mm in controls (P = 8.8 × 10-7). Both effects were confirmed in age-matched controls, and remained significant after correction for significant effects of age and axial globe length (P = 0.005).ConclusionsAlthough tethering and elongation of ON and sheath are normal in adduction, adduction is associated with abnormally great globe retraction in POAG without elevated IOP. Traction in adduction may cause mechanical overloading of the ON head and peripapillary sclera, thus contributing to or resulting from the optic neuropathy of glaucoma independent of IOP