1,277 research outputs found
Analytic height correlation function of rough surfaces derived from light scattering
We derive an analytic expression for the height correlation function of a
rough surface based on the inverse wave scattering method of Kirchhoff theory.
The expression directly relates the height correlation function to diffuse
scattered intensity along a linear path at fixed polar angle. We test the
solution by measuring the angular distribution of light scattered from rough
silicon surfaces, and comparing extracted height correlation functions to those
derived from atomic force microscopy (AFM). The results agree closely with AFM
over a wider range of roughness parameters than previous formulations of the
inverse scattering problem, while relying less on large-angle scatter data. Our
expression thus provides an accurate analytical equation for the height
correlation function of a wide range of surfaces based on measurements using a
simple, fast experimental procedure.Comment: 6 pages, 5 figures, 1 tabl
Identifying Retweetable Tweets with a Personalized Global Classifier
In this paper we present a method to identify tweets that a user may find
interesting enough to retweet. The method is based on a global, but
personalized classifier, which is trained on data from several users,
represented in terms of user-specific features. Thus, the method is trained on
a sufficient volume of data, while also being able to make personalized
decisions, i.e., the same post received by two different users may lead to
different classification decisions. Experimenting with a collection of approx.\
130K tweets received by 122 journalists, we train a logistic regression
classifier, using a wide variety of features: the content of each tweet, its
novelty, its text similarity to tweets previously posted or retweeted by the
recipient or sender of the tweet, the network influence of the author and
sender, and their past interactions. Our system obtains F1 approx. 0.9 using
only 10 features and 5K training instances.Comment: This is a long paper version of the extended abstract titled "A
Personalized Global Filter To Predict Retweets", of the same authors, which
was published in the 25th ACM UMAP conference in Bratislava, Slovakia, in
July 201
Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications
Ultrafine WO3 nanoparticles were synthesized by nanocasting route, using mesoporous SiO2 as a template. BET measurements showed a specific surface area of 700 m 2/gr for synthesized SiO2, while after impregnation and template removal, this area was reduced to 43 m 2/gr for WO3 nanoparticles. HRTEM results showed single crystalline nanoparticles with average particle size of about 5 nm possessing a monoclinic structure, which is the favorite crystal structure for gas sensing applications. Gas sensor was fabricated by deposition of WO3 nanoparticles between electrodes via low frequency AC electrophoretic deposition. Gas sensing measurements showed that this material has a high sensitivity to very low concentrations of NO2 at 250°C and 300°C
EXPLORING THE ADOPTION OF UBIQUITOUS INFORMATION SYSTEMS WITHIN THE MUSEUM CONTEXT
Wireless and mobile technologies are gradually enabling the provision of innovative information services within almost all environments. This study explores the adoption of ubiquitous museum information systems that can significantly enhance and enrich the museum visit. We draw on traditional IS adoption theories and theories from Museum Studies to develop our theoretical model which is empirically tested through a survey addressed to museum visitors (n=118). Model hypotheses are tested through Partial Least Squares modelling. The results show that Performance Expectancy and Personal Innovativeness still represent the core predictors toward the adoption of museum information systems. However, we also report on the predictive strength of two context-related factors, Invisibility and Interaction, which appear to play a particular role toward the formulation of favourable user perceptions. The paper concludes with implications on the design of museum information systems and specific suggestions for future research
Product assurance technology for procuring reliable, radiation-hard, custom LSI/VLSI electronics
Advanced measurement methods using microelectronic test chips are described. These chips are intended to be used in acquiring the data needed to qualify Application Specific Integrated Circuits (ASIC's) for space use. Efforts were focused on developing the technology for obtaining custom IC's from CMOS/bulk silicon foundries. A series of test chips were developed: a parametric test strip, a fault chip, a set of reliability chips, and the CRRES (Combined Release and Radiation Effects Satellite) chip, a test circuit for monitoring space radiation effects. The technical accomplishments of the effort include: (1) development of a fault chip that contains a set of test structures used to evaluate the density of various process-induced defects; (2) development of new test structures and testing techniques for measuring gate-oxide capacitance, gate-overlap capacitance, and propagation delay; (3) development of a set of reliability chips that are used to evaluate failure mechanisms in CMOS/bulk: interconnect and contact electromigration and time-dependent dielectric breakdown; (4) development of MOSFET parameter extraction procedures for evaluating subthreshold characteristics; (5) evaluation of test chips and test strips on the second CRRES wafer run; (6) two dedicated fabrication runs for the CRRES chip flight parts; and (7) publication of two papers: one on the split-cross bridge resistor and another on asymmetrical SRAM (static random access memory) cells for single-event upset analysis
Impact of heterotopic ossifcation following lumbar total disk replacement: a systematic review
This is the final version. Available on open access from BMC via the DOI in this recordAvailability of data and materials:
All data generated and analysed during this study are included in this published article.Background context
Lumbar total disc replacement (TDR) is an alternative to lumbar fusion in the treatment of lower back pain and reduces the risk of adjacent segment degeneration. Heterotopic ossification (HO) has been identified as a common complication following lumbar TDR.
Purpose
This systematic review aims to determine the prevalence, risk factors and clinical and radiological impact of HO following lumbar TDR.
Study Design
Systematic Review.
Methods
MEDLINE, Scopus, PubMed and Cochrane Central were searched for articles that referred to lumbar TDR and HO. The hits were assessed against inclusion and exclusion criteria. Data from each included study was extracted and analysed with respect to the study aims.
Results
Twenty-six studies were included in this review and the pooled prevalence of HO was estimated to be between 13.2% (participants) and 15.3% (vertebral levels). TDR clinical outcomes were not found to be reduced by HO and there was insufficient data to identify a given impact upon radiological outcomes. Age and follow up time were identified as potential risk factors for HO.
Conclusions
This review was hampered by inconsistencies in the reporting of HO across the studies. We therefore recommend that a set of guidelines should be produced to aid future researchers and reduce the risk of bias
Associations Between Presenting Symptoms, Clinicopathological Parameters, and Prognosis in a Contemporary Series of Patients With Renal Cell Carcinoma
PURPOSE: To evaluate the impact of presenting symptoms on survival in a contemporary series of patients with renal cell carcinoma (RCC).
MATERIALS AND METHODS: We prospectively recorded data on the presenting symptoms, pathology, and RCC-specific survival of 633 consecutive RCC patients who underwent surgery between 2003 and 2012.
RESULTS: Four hundred thirty-three RCCs (68%) were incidental, 111 (18%) were associated with local symptoms, and 89 (14%) were associated with systemic symptoms. Among those with incidental RCC, 317 patients (73%) were completely asymptomatic and 116 patients (27%) presented with symptoms not related to the tumor. During a median follow-up interval of 40 months (interquartile range: 39 to 69 months), 77 patients died from RCC. In univariate analyses, symptom classification was significantly associated with RCC-specific survival (p<0.001). Patients with incidental RCC and unrelated symptoms tended to have worse prognosis than did patients who were completely asymptomatic, although this difference was not statistically significant (p=0.057). The symptom classification was associated with advanced TNM stages (p<0.001) and grade (p<0.001).
CONCLUSIONS: This study confirms that presenting symptoms are associated with tumor characteristics and survival. The majority of RCCs are diagnosed incidentally in patients without any symptoms or with symptoms not related to RCC. Patients in the latter group tend to have a worse prognosis than do patients who are completely asymptomatic. With the increasing number of incidentally diagnosed RCCs, substratification of patients with incidental tumors may be prognostically relevant
Bacterial Symbiont Bioactive Compound of Soft Coral Sinularia Flexibilis and S. Polydactyla
Symbiont bacteria on soft coral can produce bioactive compounds that plays an important role in chemical ecology and as a marine natural product. The purpose of this study was to find and characterize the antibacterial activities of active compounds extracted from bacterial symbionts of soft coral S. flexibilis and S. polydactyla. The methods used in this study were culture and isolation of bacterial symbionts, extraction of compounds, antibacterial bioassay, and identification of bioactive compounds using the LC-MS analyses. Four isolates of bacterial symbionts were obtained from two samples of soft corals, 2 isolates of Pseudomonas diminuta (A1) and Edwardsiellla hoshinae (A2) from soft coral S. flexibilis, and 2 isolates of E. hoshinae (B1) and P. acidovorans (B4) from S. polydactila. Antibacterial activity were found only from the extracts of bacterial symbionts P. diminuta (A1) and from S. flexiblis about 10.16 ± 0.3mm (for B. subtilis), 8.66 ± 0.8 mm (E. coli) and 9.86 ± 1.7mm (S. dysentri). No antibacterial activity found from the extracts of S. polydactyla. The results of LC MS analysis showed that the group of diterpenes sinularin produced by soft corals S. flexibilis and bacterial symbionts isolates of P. diminuta (A1)
Ethylene and Anti-Ethylene Treatment Effects on Cut "First Red" Rose
Studies were conducted to determine the effects of ethylene and anti-ethylene treatments on postharvest life of cut "First Red" rose flowers. Effects of exogenous ethylene at 1, 10 and 100 ul l-1 for 48 h at 22 C on cut "First Red" rose flowers were investigated. Ethylene at different concentrations reduced postharvest life, with 100 ul l-1 having the greatest effect. Ethylene production measurements suggested that "First Red" rose is climacteric during senescence. Pre-treatment of "First Red" rose flowers with 0.5 mM silver thiosulfate (STS) for 2 h at 22 C increased vase life, but pre-treatment with 1 ul l-1 1- methylcyclopropene (1-MCP) did not. Pre-treatment of "First Red" rose with 0.5 mM STS and, to a lesser extent, 1 ul l-1 1-MCP for 2 h at 22 C, protected flowers from subsequent exposure to 10 ul l-1 ethylene. Maximum vase life in both ethylene-treated and non-ethylene-treated "First Red" rose flowers was obtained with 0.5 mM STS
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