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Urban slums provide suitable conditions for infestation by rats, which harbour and shed a wide diversity of zoonotic pathogens including helminths. We aimed to identify risk factors associated with the probability and intensity of infection of helminths of the digestive tract in an urban slum population of Rattus norvegicus. Among 299 rats, eleven species/groups of helminths were identified, of which Strongyloides sp., Nippostrongylus brasiliensis and, the human pathogen, Angiostrongylus cantonensis were the most frequent (97, 41 and 39%, respectively). Sex interactions highlighted behavioural differences between males and females, as eg males were more likely to be infected with N. brasiliensis where rat signs were present, and males presented more intense infections of Strongyloides sp. Moreover, rats in poor body condition had higher intensities of N. brasiliensis. We describe a high global richness of parasites in R. norvegicus, including five species known to cause disease in humans. Among these, A. cantonensis was found in high prevalence and it was ubiquitous in the study area – knowledge which is of public health importance. A variety of environmental, demographic and body condition variables were associated with helminth species infection of rats, suggesting a comparable variety of risk factors for humans.
Extended-spectrum β-lactamase (ESBL) production has been very rare in serotype K1 Klebsiella pneumoniae ST23 strains, which are well-known invasive community strains. Among 92 ESBL-producing strains identified in 218 isolates from nine Asian countries, serotype K1 K. pneumoniae strains were screened. Two ESBL-producing K. pneumoniae isolates from Singapore and Indonesia were determined to be serotype K1 and ST23. Their plasmids, which contain CTX-M-15 genes, are transferable rendering the effective transfer of ESBL resistance plasmids to other organisms.
(Solar Phys.). Microwave burst data from the August 7, 1972 event recorded on nine discrete frequencies between 245 and 35000 MHz at the Sagamore Hill Radio Observatory (Figure 1) provide a basis for correlation studies (especially timing information) of the associated white light flare, the high energy particle emission, type II bursts, and many other phenomena. This is perhaps the first time that sufficient radio coverage (i.e., data above 10000 MHz) was available to obtain the spectral slope information (related to electron-energy distribution) which is inherent in this part of the spectrum. Heretofore, timing was related to burst flux density profile variations. Improved correlations resulted from shorter centimeter wavelength data which supplied more accurate timing information than that derived from Hα observations. The shape and intensity of the burst peak flux density spectrum has also been used for qualitative analysis of energetic particle and white light events. The ultimate good may possibly come from spectral analysis of the minute by minute variation of the burst microwave radiation spectral slope α (above fmax) in the area between 15000 and 35000 MHz. This may be used alone or in relation to the position of fmax, where fmax is the frequency of burst maximum emission at a given time. This is basically our present investigation.
Leptospirosis is a zoonosis caused by bacteria of the genus Leptospira. The disease is globally distributed and a major public health concern. The Norway rat (Rattus norvegicus) is the main reservoir of the pathogen in urban slums of developing and developed countries. The potential routes of intra-specific leptospire transmission in rats are largely unknown. Herein, we identified pathogenic Leptospira spp. in breast tissue and milk of naturally infected rats. We examined kidney, breast tissue and milk from 24 lactating rats for the presence of leptospires using immunofluorescence, immunohistochemistry, polymerase chain reaction (PCR) and scanning electronic microscopy. All 24 rats had evidence for Leptospira in the kidneys, indicating chronic carriage. The majority of kidney-positive rats had detectable leptospires in milk (18, 75%) and breast tissue (16, 67%), as evidenced by immunofluorescence assay and immunohistochemistry. Four (17%) milk samples and two (8%) breast tissue samples were positive by quantitative real-time PCR. Scanning electron microscopy confirmed the presence of leptospires in breast tissue. No major pathological changes in breast tissue were found. This study, for the first time, identified leptospires in the milk and breast tissue of wild Norway rats, suggesting the possibility of milk-borne transmission of leptospirosis to neonates.
Research in radio astronomy at the Ohio State University covers a wide range of astronomical and engineering phases. In this paper the principal topics currently under investigation are briefly discussed. Reference is made to more detailed papers or reports published within recent months or now in the press.
Magnetic fields in the solar atmosphere provide the energy for most varieties of solar activity, including high-energy electromagnetic radiation, solar energetic particles, flares, and coronal mass ejections, as well as powering the solar wind. Despite the fundamental role of magnetic fields in solar and heliospheric physics, there exist only very limited measurements of the field above the base of the corona. What is needed are direct measurements of not only the strength and orientation of the magnetic field but also the signatures of wave motions in order to better understand coronal structure, solar activity, and the role of MHD waves in heating and accelerating the solar wind. Fortunately, the remote sensing instrumentation used to make magnetic field measurements is also well suited to measure the Doppler signature of waves in the solar structures. We present here a mission concept for the Waves And Magnetism In the Solar Atmosphere (WAMIS) experiment which is proposed for a NASA long-duration balloon flight.
To investigate the risk of completed suicide in offspring during adolescence in relation to prior history of the same-sex parent's death by suicide and other causes.
A total of 500 adolescents who died by suicide at age 15–19 years between 1997 and 2007 were identified from the Taiwan Mortality Registration (TMR). For each case, 30 age- and time-matched controls were selected randomly from all adolescents registered in the Taiwan Birth Registry (TBR). A multivariate conditional logistic regression model was used to assess the risk of adolescent completed suicide in relation to their same-sex parent.
Adolescent suicide risk was positively associated with both paternal [odds ratio (OR) 5.38, 95% confidence interval (CI) 2.17–13.33] and maternal suicide (OR 6.59, 95% CI 1.82–23.91). The corresponding risk estimates associated with paternal and maternal deaths from non-suicidal causes were much lower, at 1.88 and 1.94 respectively. The risk of suicide in male adolescents was significantly associated with prior history of paternal death by suicide (OR 8.23, 95% CI 2.96–22.90) but not of maternal death by suicide (OR 3.50, 95% CI 0.41–30.13). On the other contrary, the risk of suicidal death in female adolescents was significantly associated with prior history of maternal suicide (OR 9.71, 95% CI 1.89–49.94) but not of paternal suicide (OR 2.42, 95% CI 0.30–19.57). However, these differences did not reach statistical significance.
Although limited by sample size, our study indicates that adolescent offspring suicidal death is associated with prior history of their same-sex parent's death by suicide.
Shigella flexneri 4a caused sustained outbreaks in a large long-stay psychiatric centre, Taiwan, 2001–2006. Trimethoprim-sulphamethoxazole (SXT) prophylaxis was administered in 2004. We recovered 108 S. flexneri 4a isolates from 83 symptomatic (including one caregiver) and 12 asymptomatic subjects (11 contacts, one caregiver). The isolates were classified into eight antibiogram types and 15 genotypes (six clusters) by using antimicrobial susceptibility testing and pulsed-field gel electrophoresis of NotI-digested DNA, respectively. These characteristics altered significantly after SXT prophylaxis (P < 0·05), with concomitant emergence of SXT-resistant isolates in two antibiogram types. P01 (n = 71), the predominant epidemic genotype, caused infection in two caregivers and five patients under their care; two P01 isolates were recovered from the same patient 6 months apart. These results indicate the importance of sustained person-to-person transmission of S. flexneri 4a by long-term convalescent, asymptomatic or caregiver carriers, and support the emergence of SXT-resistant strains following selective pressure by SXT prophylaxis.
The purpose of this study was to understand the seasonal, geographical and clinical characteristics of Taiwanese patients hospitalized for non-typhoidal Salmonella (NTS) infections and their economic burden. Hospital data obtained from the Taiwan National Health Insurance (NHI) database between 2006 and 2008 were analysed. Infants had the highest annual incidence of 525 cases/100 000 person-years. Elderly patients aged >70 years had the highest in-hospital mortality rate (2·6%). Most (82·6%) gastroenteritis occurred in children aged <10 years. Septicaemia, pneumonia, arthritis and osteomyelitis occurred mainly in patients aged >50 years. A median medical cost for NTS-associated hospitalizations was higher for patients with septicaemia than for those with gastroenteritis. Seasonal variation of NTS-associated hospitalizations was correlated with temperature in different areas of Taiwan. In summary, infants had a high incidence of NTS-associated hospitalizations. However, the elderly had a higher in-hospital mortality rate and more invasive NTS infections than children.
Non-typhoidal Salmonella (NTS) is a common pathogen causing foodborne infections, bacteraemia, and extra-intestinal focal infections (EFIs) in humans. The study compares the clinical characteristics of elderly patients with NTS bacteraemia with those of young adults. Of 272 adults with NTS bacteraemia identified in this study, 162 (59·6%) were aged ⩾55 years. EFIs were observed in 36% of the 162 patients. The most common EFIs in the elderly patients (⩾55 years) was mycotic aneurysm, followed by pulmonary infections and bone/joint infections. Elderly patients more often had chronic heart, lung, renal and malignant diseases, had more EFIs, and a higher 30-day mortality rate. Independent factors of 30-day mortality in elderly patients were solid-organ tumour [adjusted odds ratio (aOR) 4·4, P=0·003], mycotic aneurysm (aOR 3·7, P=0·023) and shock (aOR 12·1, P<0·0001). HIV infection, autoimmune diseases, and receipt of immunosuppressive therapy were more often observed in young patients.
A biomimetic process has been developed to fabricate hydroxyapatite-gelatin (HAP-GEL) nanocomposites for bone regeneration (Chang and Ko et al. 2003). We hypothesize that this newly developed HAP-GEL is osteoconductive and is suitable for tissue engineered scaffolds. This preliminary study is aimed to characterize cell affinity and osseous regeneration of the HAP-GEL. The HAP-GEL was synthesized according to the procedures described in the previous publication. The attachment and proliferation of human fetal osteoblasts on HAP-GEL discs were evaluated using three different gelatin contents (2g, 3g, and 4g). The cells were seeded onto each disc and incubated at 34 degrees Celsius in 5% CO2 air atmosphere. At different time points of cultivation, cells were stained with fluorescein diacetate (FDA) and ethidium bromide (EB) to determine their viability and morphology. To assess the cell proliferation, cells were detached at Days 1, 4, and 7 by trypsinzation and counted. For in vivo tests, HAP-GEL rods were implanted into the proximal femur of Sprague-Dawley rats. One month after the implantation, the femurs were harvested and the undecalcified HAP-GEL-bone sections were stained for histopathology. Four hours after attachment, most cells appeared round in all discs; cell spreading was observed after 24 hours. The highest gelatin content supported a significantly higher cell growth than the others at 7 days. Thus all compositions support satisfactory attachment, spreading and growth. In vivo results showed excellent interfacial bone regeneration. No necrotic tissues were found. In conclusion, the HAP-GEL not only mimics the biochemistry and nanostructures of bone but also supports the attachment, proliferation and differentiation (bone formation) of osteoblasts. The HAP-GEL we developed provides a suitable surface for regeneration.
This research focuses on the design and experimental characterization of two types of asym- metrical MEMS electrothermal microactuators. Both MEMS polysilicon electrothermal microac- tuator designs use resistive (Joule) heating to generate thermal expansion and movement. Deflection and force measurements as a function of applied electrical power are presented.
Metal organic deposition (MOD) is one of the attractive processes for coated conductor applications because it is a non-vacuum cost-effective process. Many research groups have successfully fabricated high-JC YBCO coated conductor on the RABiTS and IBAD-YSZ or GZO template with the MOD process. Reports on MOD-processed YBCO coated conductors prepared on the IBAD-MgO template, however, are hardly found. The precursor solution was coated on the CeO2 capped IBAD-MgO template using the slot-die coating method, calcined at a temperature of 550oC, and fired at high temperatures for 2 h 30 min in a reduced oxygen atmosphere. Optimal processing resulted in YBCO coated conductors exhibiting JC value of 0.75 MA/cm2 at 77 K in self-field. The JC values of YBCO coated conductors were found very sensitive to their microstructure, critical temperature, and in-plane texture.
A new polysilicon surface micromachining technique for fabricating and assembling three- dimensional structures has been developed. Single-layer polysilicon elements and laminated polysilicon panels incorporating trapped-glass reinforcement ribs have been successfully fabri- cated on a silicon substrate with robust and continuous hinges that facilitate out-of-plane rotation and assembly. To realize a stable three-dimensional structure, one of the device's elevatable panel components is terminated with an array of open windows, and the mating rotatable element has a matched set of protruding arrowheads/microrivets with flexible barbs that readily flex to facilitate their joining and assembly. Because the arrowhead/microrivet barb tip-to-barb tip sepa- ration is larger than the opening in the mating window, the barbs flex inward as they pass through the open window and then expand to their original shape upon exiting the window, re- sulting in a permanently latched joint and a three-dimensional structure. Three novel arrow- head/microrivet designs have been micromachined to facilitate the latching process, including a simple arrowhead, a high-aspect ratio arrowhead, and a rivet-like structure with a hemispherical shaped cap and a flexible split shank.
The mechanical behavior of the red blood cell membrane is governed by the lipid bilayer which resists changes in surface area and the underlying spectrin network which resists changes in shape. The spectrin network can be modeled as an idealized triangulated network. Each spectrin chain consists of folded domains along the length of the chain which can unfold during stretching of the chain. A domain will completely unfold under the application of a chain force of 20 to 35 pN depending on the rate of imposed chain stretch. During macroscopic stretch of a network, individual chains within the network will experience different levels of chain stretch since the network chains will collectively stretch and rotate to accommodate the imposed stretch. Hence, the stretch on any individual chain will depend on the magnitude and state of macroscopic strain. A microstructurally informed continuum level constitutive model is developed which tracks individual chain deformation behavior as a function of macroscopic strain and also determines the overall macroscopic network stress-strain behavior. Using the introduced continuum approach and statistical mechanics based models of individual chain force-extension behavior, the stress-stretch behavior of the membrane under uniaxial tension is simulated at large stretches and the behavior of the constituent chains is monitored. Domain unfolding occurs within constituent chains during network deformation and the effects of this domain unfolding on the overall macroscopic stress-strain behavior of the network subject to deformation at different strain rates is revealed.
The structure and behavior of proteins plays an overarching role in determining their function in biological systems. In recent years, proteins have also been proposed as basis for new materials to be used in technological applications (Langer and Tirrell, Nature, 2004). It is known that protein crystals show very interesting mechanical behavior, as some of them are extremely fragile, while others can be quite sturdy. However, unlike other crystalline materials like silicon or copper, the mechanical properties of protein crystals have rarely been studied by atomistic computer modeling. As a first step towards more fundamental understanding of the mechanics of those materials, we report atomistic studies of mechanical properties of protein crystals using empirical potentials focusing on elasticity, plasticity and fracture behavior. Here we consider the mechanics of a small protein α-conotoxin PnIB from conus pennaceus. We use large-scale atomistic simulations to determine the low-strain elastic constants for different crystallographic orientations. We also study large-strain elastic properties including plastic deformation. Furthermore, we perform systematic studies of the effect of mutations on the elastic properties of the protein crystal. Our results indicate a strong impact of mutations on elastic properties, showing the potential of mutations to tailor mechanical properties. We conclude with a study of mode I fracture of protein crystals, relating our atomistic modeling results with Griffith's theory of fracture.
A commercial polycarbosilane, thermolysis product of polysilastyrene, was spun into fibres. The self-curing character of the polymer permitted both oxidative and thermal curing of the precursor fibres. Pyrolysis of the latter produced ceramic fibres in high yields, which were fully characterised. Optimum tensile strength was attained after heat treatment at 1100°C. Oxidative reactions and crystallisation caused strength degradation above this temperature.