Monkey tests for random number generators

AbstractThis article describes some very simple, as well as some quite sophisticated, tests that shed light on the suitability of certain random number generators

Reconceptualising Personas Across Cultures: Archetypes, Stereotypes & Collective Personas in Pastoral Namibia

The paucity of projects where persona is the research foci and a lack of consensus on this artefact keep many reticent about its purpose and value. Besides crafting personas is expected to differ across cultures, which contrasts the advancements in Western theory with studies and progress in other sites. We postulate User-Created Personas reveal specific characteristics of situated contexts by allowing laypeople to design persona artefacts in their own terms. Hence analysing four persona sessions with an ethnic group in pastoral Namibia –ovaHerero– brought up a set of fundamental questions around the persona artefact regarding stereotypes, archetypes, and collective persona representations: (1) to what extent user depictions are stereotypical or archetypal? If stereotypes prime (2) to what degree are current personas a useful method to represent end-users in technology design? And, (3) how can we ultimately read accounts not conforming to mainstream individual persona descriptions but to collectives

Interface modification of clay and graphene platelets reinforced epoxy nanocomposites: a comparative study

The interface between the matrix phase and dispersed phase of a composite plays a critical role in influencing its properties. However, the intricate mecha-nisms of interface are not fully understood, and polymer nanocomposites are no exception. This study compares the fabrication, morphology, and mechanical and thermal properties of epoxy nanocomposites tuned by clay layers (denoted as m-clay) and graphene platelets (denoted as m-GP). It was found that a chemical modification, layer expansion and dispersion of filler within the epoxy matrix resulted in an improved interface between the filler mate-rial and epoxy matrix. This was confirmed by Fourier transform infrared spectroscopy and transmission electron microscope. The enhanced interface led to improved mechanical properties (i.e. stiffness modulus, fracture toughness) and higher glass transition temperatures (Tg) compared with neat epoxy. At 4 wt% m-GP, the critical strain energy release rate G1c of neat epoxy improved by 240 % from 179.1 to 608.6 J/m2 and Tg increased from 93.7 to 106.4 �C. In contrast to m-clay, which at 4 wt%, only improved the G1c by 45 % and Tg by 7.1 %. The higher level of improvement offered by m-GP is attributed to the strong interaction of graphene sheets with epoxy because the covalent bonds between the carbon atoms of graphene sheets are much stronger than silicon-based clay

The effect of distance on observed mortality, childhood pneumonia and vaccine efficacy in rural Gambia.

We investigated whether straight-line distance from residential compounds to healthcare facilities influenced mortality, the incidence of pneumonia and vaccine efficacy against pneumonia in rural Gambia. Clinical surveillance for pneumonia was conducted on 6938 children living in the catchment areas of the two largest healthcare facilities. Deaths were monitored by three-monthly home visits. Children living >5 km from the two largest healthcare facilities had a 2·78 [95% confidence interval (CI) 1·74-4·43] times higher risk of all-cause mortality compared to children living within 2 km of these facilities. The observed rate of clinical and radiological pneumonia was lower in children living >5 km from these facilities compared to those living within 2 km [rate ratios 0·65 (95% CI 0·57-0·73) and 0·74 (95% CI 0·55-0·98), respectively]. There was no association between distance and estimated pneumococcal vaccine efficacy. Geographical access to healthcare services is an important determinant of survival and pneumonia in children in rural Gambia

Identifikasi Kontribusi Pencemaran Pm10 dengan Metode Reseptor Positive Matrix Factorization (Pmf) Studi Kasus : Kota Pekanbaru Provinsi Riau

Partikulat merupakan salah satu indikator pencemar udara yang keberadaannya selalu dipantau. Keberadaan partikulat ini terutama partikulat dengan diameter 10 mikrometer atau dikenal dengan PM10 konsentrasinya selalu dipantau pada salah satunya adalah Stasiun Pemantauan Pencemar Udara Sukajadi, Kota Pekanbaru Provinsi Riau. Namun, hasil konsentrasi yang dipantau hanya akan menggambarkan besaran dari konsentrasi PM10 tersebut sehingga belum dapat menggambarkan kemungkinan sumber-sumber pencemar dari partikulat tersebut di Kota Pekanbaru. Penelitian ini akan membahas mengenai konsentrasi komposisi kimiawi yang terkandung di dalam partikulat melalui analisis kimia filter pemantauan yang terdapat pada Stasiun Pemantauan Sukajadi, Kota Pekanbaru dengan menggunakan metode Inductievly Coupled Plasma (ICP) dan Ion Chromatography (IC). Hasil analisis komposisi kimia yang didapatkan berupa unsur logam dan ion yang terdiri As, Bi, Cr, Cs, Cu, K, Li, Mn, Ni, Pb, Rb, Se, Ti, U, Zn, Fe, W, Mo, Hg, Cl-, NO3-, SO42-, K+, Mg2+, Ca2+ dan Na+. Hasil tersebut selanjutnya akan dianalisis dengan menggunakan software EPA-PMF untuk mengetahui sumber yang potensial serta besaran kontribusinya terhadap pencemar partikulat yang ada di Kota Pekanbaru. Hasil yang didapatkan adalah kemungkinan sumber-sumber dari pencemar PM10 adalah bersumber dari Pembakaran Vegetasi dengan kontribusi sebesar 39,86%, Kendaraan Bermotor 15,65%, Industri (Boiler Batubara) 17,11%, Lahan Pertanian 16,97% dan Debu Tanah 10,41

Study on knowledge, attitude and practices with respect to antibiotic use among medical students

Background: Antibiotic resistance has emerged as a serious global problem. Irrational prescribing of antibiotics is one of the key factors responsible for the development of antibiotic resistance. As today’s medical students will be the future prescribers their awareness regarding antibiotic resistance and rational prescribing of antibiotics is very much important. The main objective of the study was to evaluate the knowledge, attitude and practices of the medical students towards antibiotic use.Methods: A cross-sectional questionnaire-based study was conducted involving the medical students from all the semesters. A predesigned questionnaire was used to evaluate the knowledge, attitude and practices of the respondents. The response options were ‘yes’ or ‘no’ for some questions, and a 5 point Likert scale used to assess some questions. The data was analyzed using MS office Excel.Results: A total of 457 fully completed questionnaires from the respondents were evaluated. Majority of the respondents (70%) were females, and 91% of the respondents were aware of antibiotic resistance as a global problem. On analysis of score of questions assessing knowledge, 91% of respondents had attained a score in the range of 5-7. Majority (83%) of the respondents used antibiotics only on doctor’s prescription and 74% of the respondents had completed the prescribed course.Conclusions: The present study gives an insight on the knowledge, attitude and practices of medical students on antibiotic use, and can be used as a tool to plan educational strategies to improve the knowledge of the students regarding rational use of antibiotics

Antenna Near-Field Probe Station Scanner

A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described

Probe Station and Near-Field Scanner for Testing Antennas

A facility that includes a probe station and a scanning open-ended waveguide probe for measuring near electromagnetic fields has been added to Glenn Research Center's suite of antenna-testing facilities, at a small fraction of the cost of the other facilities. This facility is designed specifically for nondestructive characterization of the radiation patterns of miniaturized microwave antennas fabricated on semiconductor and dielectric wafer substrates, including active antennas that are difficult to test in traditional antenna-testing ranges because of fragility, smallness, or severity of DC-bias or test-fixture requirements. By virtue of the simple fact that a greater fraction of radiated power can be captured in a near-field measurement than in a conventional far-field measurement, this near-field facility is convenient for testing miniaturized antennas with low gains

Network development in biological gels: role in lymphatic vessel development

In this paper, we present a model that explains the prepatterning of lymphatic vessel morphology in collagen gels. This model is derived using the theory of two phase rubber material due to Flory and coworkers and it consists of two coupled fourth order partial differential equations describing the evolution of the collagen volume fraction, and the evolution of the proton concentration in a collagen implant; as described in experiments of Boardman and Swartz (Circ. Res. 92, 801–808, 2003). Using linear stability analysis, we find that above a critical level of proton concentration, spatial patterns form due to small perturbations in the initially uniform steady state. Using a long wavelength reduction, we can reduce the two coupled partial differential equations to one fourth order equation that is very similar to the Cahn–Hilliard equation; however, it has more complex nonlinearities and degeneracies. We present the results of numerical simulations and discuss the biological implications of our model

Bone mineral density in breast cancer patients treated with adjuvant letrozole, tamoxifen, or sequences of letrozole and tamoxifen in the BIG 1-98 study (SAKK 21/07)

Background: The risk of osteoporosis and fracture influences the selection of adjuvant endocrine therapy. We analyzed bone mineral density (BMD) in Swiss patients of the Breast International Group (BIG) 1-98 trial [treatment arms: A, tamoxifen (T) for 5 years; B, letrozole (L) for 5 years; C, 2 years of T followed by 3 years of L; D, 2 years of L followed by 3 years of T]. Patients and methods: Dual-energy X-ray absorptiometry (DXA) results were retrospectively collected. Patients without DXA served as control group. Repeated measures models using covariance structures allowing for different times between DXA were used to estimate changes in BMD. Prospectively defined covariates were considered as fixed effects in the multivariable models. Results: Two hundred and sixty-one of 546 patients had one or more DXA with 577 lumbar and 550 hip measurements. Weight, height, prior hormone replacement therapy, and hysterectomy were positively correlated with BMD; the correlation was negative for letrozole arms (B/C/D versus A), known osteoporosis, time on trial, age, chemotherapy, and smoking. Treatment did not influence the occurrence of osteoporosis (T score < −2.5 standard deviation). Conclusions: All aromatase inhibitor regimens reduced BMD. The sequential schedules were as detrimental for bone density as L monotherap