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Genetic selection for litter size received little attention either by scientists or commercial pig breeders until recently. Low heritability of litter size, its sex-limited expression and the fact that it cannot be measured until reproductive maturity are often given as reasons. But the major reason may be that the reproductive rate of pigs is already quite high, and the economic value of genetic changes in litter size have been small relative to those of efficiency and composition of growth.
The economics of pig production have changed and technological and biological advances have caused us to re-examine the economic value of traits. Reducing fat in the carcass and more efficient conversion of feed to lean meat have always been, and will continue to be, high priority selection objectives for pig breeders. But expensive, environmentally controlled gestation, farrowing and nursery houses are the norm of modern pig production and increasing litter size will result in a significant reduction in the cost of producing lean meat (Tess et al., 1983).
Identifying the transmission sources and reservoirs of Streptococcus pneumoniae (SP) is a long-standing question for pneumococcal epidemiology, transmission dynamics, and vaccine policy. Here we use serotype to identify SP transmission and examine acquisitions (in the same household, local community, and county, or of unidentified origin) in a longitudinal cohort of children and adults from the Navajo Nation and the White Mountain Apache American Indian Tribes. We found that adults acquire SP relatively more in the household than other age groups, and children 2–8 years old typically acquire in their own or surrounding communities. Age-specific transmission probability matrices show that transmissions within household were mostly seen from older to younger siblings. Outside the household, children most often transmit to other children in the same age group, showing age-assortative mixing behavior. We find toddlers and older children to be most involved in SP transmission and acquisition, indicating their role as key drivers of SP epidemiology. Although infants have high carriage prevalence, they do not play a central role in transmission of SP compared with toddlers and older children. Our results are relevant to inform alternative pneumococcal conjugate vaccine dosing strategies and analytic efforts to inform optimization of vaccine programs, as well as assessing the transmission dynamics of pathogens transmitted by close contact in general.
Real-time detection of microlensing has moved from proof of concept in 1994 (Udalski et al. 1994a, Alcock et al. 1994) to a steady stream of events this year. Global dissemination of these events by the MACHO and OGLE collaborations has made possible intensive photometric and spectroscopic follow up from widely dispersed sites confirming the microlensing hypothesis (Benetti 1995). Improved photometry and increased temporal resolution from follow up observations greatly increases the possibility of detecting deviations from the standard point-source, point-lens, inertial motion microlensing model. These deviations are crucial in understanding individual lensing systems by breaking the degeneracy between lens mass, position and velocity. We report here on GMAN (Global Microlensing Alert Network), the coordinated follow up of MACHO alerts.
We describe the search for δ Scuti stars in the MACHO database of bulge fields. Concentrating on a sample of high amplitude δ Scutis, we examine the light curves and pulsation modes. We also discuss their spatial distribution and evolutionary status using mean colors and absolute magnitudes.
Gravitational microlensing is the most straightforward interpretation of the stellar brightenings that have been observed by our team and other experiments. These data have provided some of the most stringent limits to date on the nature of the Galaxy's dark matter halo. The number of events seen towards the LMC indicate that our Galaxy is not surrounded by a “standard” halo of MACHOs in the mass range of 10–6 to 0.3 solar masses. The observed optical depth towards the Galactic Center is an important constraint on the distribution of mass in the plane of the Galaxy.
We have analyzed a sample of 1150 type ab, and 550 type c RR Lyrae stars found in 24 of 94 bulge fields of the MACHO database. These fields cover a range in Galactocentric distances from 0.3 to 1.6 kpc. In combination with the data on the outer bulge fields of Alard (1997) and Wesselink (1987), here we present the surface density distribution of bulge RR Lyrae between 0.3 and 3 kpc.
The MACHO microlensing experiment's time-sampled photometry database contains blue and red lightcurves for nearly 9 million stars in the central bar region of the Large Magellanic Cloud (LMC). We have identified known LMC Planetary Nebulae (PN) in the database and find one, Jacoby 5, to be variable. We additionally present data on the “parent populations” of LMC PN, and discuss the star formation history of the LMC bar.
A low-cost differential image motion monitor (DIMM), consisting of an 11-inch Celestron, an SBIG ST-4 autoguiding CCD camera and a PC, is described. Two such systems were used during June–July and November–December 1993 to make near-simultaneous seeing measurements at Freeling Heights in the Northern Flinders Ranges and at Siding Spring Observatory. The results of these campaigns show that the seeing-distribution is generally similar at both sites, with the most common seeing value being ~l·2″. Siding Spring does, however, have slightly more bad seeing (>2″) than Freeling Heights. Weather records from Arkaroola Resort (15 km south of Freeling Heights) indicate that there is ~15% less cloud cover at Freeling Heights than at Siding Spring. Episodes of rapid seeing deterioration at Siding Spring in winter are shown to coincide with warm air masses crossing the mountain.
In the past few years, the Magellanic Clouds have been the targets for several major variable star surveys. The results of these surveys are now becoming available and it is clear that a Renaissance in LMC and SMC variable star research will result. In this review, I will describe the results of such surveys and review the questions that are likely to be answered by further work.
With respect to results, I will concentrate on LMC MACHO Project data, including beat Cepheids, discovery statistics, mode identification, Fourier decomposition of lightcurves, and the differences between the LMC and galactic sample.
The MACHO Collaboration’s search for baryonic dark matter via its gravitational microlensing signature has generated a massive database of time ordered photometry of millions of stars in the LMC and the bulge of the Milky Way. The search’s experimental design and capabilities are reviewed and the dark matter results are briefly noted. Preliminary analysis of the ~ 39,000 variable stars discovered in the LMC database is presented and examples of periodic variables are shown. A class of a periodically variable Be star is described which is the closest background to microlensing which has been found. Plans for future work on variable stars using the MACHO data are described.
We present the first results of the analysis of 22 Blazhko stars. We find: 1) Blazhko RRab stars that are nearly pure amplitude modulators; 2) Blazhko RRab stars that have both amplitude and phase modulation; 3) A Blazhko RRab star that has an abrupt period change; 4) Proof of the Blazhko effect in RRc stars. Our data show the character of the amplitude and phase modulations of the light curves over the Blazhko cycles far better than has been previously possible.
We present optical photometry of the eclipsing supersoft source, CAL 87. We find the eclipse structure to be stable over ~ 4 y, derive an improved ephemeris of To = HJD 2450111.5144(3)+0.442674(7)E, and see new structure in the light curve morphology.
We present the preliminary results of a frequency analysis of 1457 fundamental mode RR Lyrae (RR0) stars in the Large Magellanic Cloud (LMC) from MACHO Project photometry. We find the same classes of pulsational behavior as were found in our earlier survey of first overtone RR Lyrae (RR1) stars. Variables whose prewhitened power spectra contain one or two peaks close to the main frequency component in the original power spectra are commonly known as Blazhko-type variables. The present analysis shows the overall frequency of Blazhko-type stars in the total RR0 population analysed to date to be ≈ 10%. This is lower than the often cited Galactic field/globular rate of 20-30% (Szeidl, 1988).
The incidence rate of Blazhko-type variability in the LMC appears to be about three times higher in RR0 stars than in RR1 stars. This puts important constraints on possible models of the Blazhko effect.
We present the first massive frequency analysis of the 1200 first overtone RR Lyrae stars in the Large Magellanic Cloud observed in the first 4.3 yr of the MACHO project. Besides the many new double-mode variables, we also discovered stars with closely spaced frequencies. These variables are most probably nonradial pulsators.
Single wall carbon nanotubes (SWCNTs) and liquid-phase exfoliated multilayer graphene (MLG) material thin films were assembled at a polarizable organic/water interface. A simple, spontaneous route to functionalize/decorate the interfacial assembly of MLG and SWCNTs with noble metal nanoparticles, at the interface between two immiscible electrolyte solutions (ITIES), is reported. The formation of MLG- or SWCNT-based metal nanocomposites was confirmed using various microscopic (scanning electron, transmission electron, and atomic force microscopy) and several spectroscopic (energy dispersive x-ray and Raman spectroscopy) techniques. Increasing the interfacial deposition time of the metal nanoparticles on the assembled low-dimensional carbon material increased the amount of the metal particles/structures, resulting in greater coverage of the MLG or SWCNTs with metal nanoparticles. This low-cost and convenient solution chemistry based impregnation method can serve as a means to prepare nanoscale carbonaceous material-based metal nanocomposites for their potential exploitation as electro-active materials, e.g., new generation catalysts or electrode materials.
To report a case of meningioma arising from the nervus intermedius.
This paper comprises a case report, literature review, and discussion regarding the presentation of a nervus intermedius meningioma, comparing and contrasting this to other relevant neoplasms of the internal auditory canal and cerebellopontine angle.
Tumours of the cerebellopontine angle include vestibular schwannomas, facial schwannomas and, more rarely, nervus intermedius schwannomas. The nervus intermedius is a division of the facial nerve at the cerebellopontine angle, with parasympathetic and afferent somatic components. Our patient presented with progressive hearing loss. An ipsilateral internal auditory canal mass at the fundus, as indicated by magnetic resonance imaging and electroneuronography, was suggestive of vestibular schwannoma. Intra-operative dissection revealed a nervus intermedius tumour. Histological evaluation indicated a meningioma rather than a schwannoma.
This is the first reported case of meningioma involving the nervus intermedius. The implications this pathology may have on surgical approach, facial nerve outcomes, and the need for improved pre-operative imaging and intra-operative monitoring are discussed. A review of the current literature on nervus intermedius tumour is provided.
The optical properties and electronic structure of AlPO4, SiO2, Type I collagen, and DNA were examined to gain insight into the van der Waals-London dispersion behavior of these materials. Interband optical properties of AlPO4 and SiO2 were derived from vacuum ultraviolet spectroscopy and spectroscopic ellipsometry, and showed a strong dependence on the crystals’ constituent tetrahedral units, with strong implications for the role of phosphate groups in biological materials. The UV-Vis decadic molar absorption of four DNA oligonucleotides was measured, and showed a strong dependence on composition and stacking sequence. A film of Type I collagen was studied using spectroscopic ellipsometry, and showed a characteristic shoulder in the fundamental absorption edge at 6.05 eV. Ab initio calculations based on density functional theory corroborated the experimental results and provided further insights into the electronic structures, interband transitions and vdW-Ld interaction potentials for these materials.
This study investigated the relationships among stress, intrapersonal resiliency factors (self-esteem, locus of control, and optimism) and quality of life [QOL] (physical health and mental health) among caregivers of children with high functioning autism spectrum disorders (HFASDs). Participants consisted of 113 caregivers of children with HFASDs (males = 38.1%, females = 61.9%; age range = 27–62; 93.6% Caucasians) and 47 caregivers of typically developing children (males = 29.8%; females = 70.2%; age range = 30–56; 93.3% Caucasians). They completed a set of self-rating surveys on perceived locus of control, self-esteem, optimism, and QOL. Within-group inferential statistical analyses were applied. For the HFASD group analyses, two simultaneous regression analyses were used to study the independent effects of the three intrapersonal variables on the physical health and mental health QOL of the caregivers. Intrapersonal factors predicted self-reported mental health QOL but not physical health QOL in caregivers of children with HFASDs.
Aragonite can grow from calcium carbonate solutions as the favored phase, at ambient conditions, in the presence of 1:1 volume % water:ethanol. Its form is single and branched needles, with pseudohexagonal symmetry. Morphological evidence demonstrates that all precipitated aragonite is twinned. The recently popularized hypothesis of nonclassical growth by nanocrystal self assembly cannot describe the aragonite crystal form. Rather, its formation is effectively described as spherulitic growth, i.e. by classical crystal growth theory.