The isotropic correlation function of plane figures: the triangle case

The knowledge of the isotropic correlation function of a plane figure is useful to determine the correlation function of the cylinders having the plane figure as right-section and a given height as well as to analyze the out of plane intensity collected in grazing incidence small-angle scattering from a film formed by a particulate collection of these cylinders. The correlation function of plane polygons can always be determined in closed algebraic form. Here we report its analytic expression for the case of a triangle. The expressions take four different forms that depend on the relative order among the sides and the heights of the triangle.Comment: 11 pages, 2 figure

Breeding for improved responsiveness to arbuscular mycorrhizal fungi in onion

Arbuscular mycorrhizal fungi (AMF) play an important role in the uptake of nutrients and water from soil. Onions, Allium cepa L., are plants with a shallow root system. As a result, onion plants need a lot of fertiziler for their growth. Furthermore, onion plants are sensitive to drought. The aim of the current research project is to study the beneficial effect of mycorrhizal fungi on the growth and development of Allium species and to determine whether it is possible to improve onions for mycorrhizal responsiveness by means of breeding. Variation among Allium species and segregation observed in a interspecific tri-hybrid population indicate that selection and thus breeding for high responsiveness to AMF is possible

A fifty year record of winter glacier melt events in southern Chile, 38°–42°S

Little is known about the frequency and potential mass balance impact of winter glacier melt events. In this study, daily atmospheric temperature soundings from the Puerto Montt radiosonde (41.43°S) are used to reconstruct winter melting events at the glacier equilibrium line altitude in the 38°–42°S region of southern Chile, between 1960 and 2010. The representativeness of the radiosonde temperatures to near-surface glacier temperatures is demonstrated using meteorological records from close to the equilibrium line on two glaciers in the region over five winters. Using a degree-day model we estimate an average of 0.28 m of melt and 21 melt days in the 15 June–15 September period each year, with high inter-annual variability. The majority of melt events are associated with midlatitude migratory high pressure systems crossing Chile and northwesterly flows, that force adiabatic compression and warm advection, respectively. There are no trends in the frequency or magnitude of melt events over the period of record, but the annual frequency of winter melt days shows a significant, although rather weak and probably non-linear, relationship to late winter and early spring values of a multivariate El Niño Southern Oscillation Index (MEI)

Bobwhite Brood Ecology in Relation to Fallow Field Management Techniques and Prescribed Fire Regime

We used compositional analysis to rank habitats used by nesting and brood-rearing northern bobwhites (Colinus virginianus) in northern Florida. We used a residence index based on brood movement rates and turning angles to predict distribution of organisms among habitat types within brood ranges. We examined relationships among residence indices and vegetation and invertebrate characteristics of the habitat to draw inferences as to brood habitat quality. We related brood survival to vegetation, landscape structure and composition, and invertebrate characteristics within brood ranges. Finally, we reported effects of season of disking (fall vs spring) on vegetative (composition, canopy cover, density, ground cover) and invertebrate (richness and biomass) communities in fallow agricultural fields

Evaluation of Two Marking Methods for 1-day-old Northern Bobwhite Chicks

We compared survival, weight gain, and mark retention of wing bands (n = 50), passive integrated transponders (PITs)(n = 50), and leg bands proportional to the chicks size (control) (n = 50) on 1-day-old northern bobwhite (Colinus virginianus) chicks. A repeated measures, generalized complete randomized block ANOV A of the weekly gain in weight showed no difference in the chicks growth (p \u3e) 0.05). Survival was similar between marking methods (wing band, PITs, leg band, and control). Retention of bands during the twelve-week pen study were equal but 4% of PITs were destroyed when adult birds were recovered after harvest. We concluded that wing bands may be the most practical method of marking 1-day-old bobwhite chicks

Effects of Radio-Transmitters on Body Condition, Harvest Rate, and Survival of Bobwhites

Numerous studies of northern bobwhite (Colinus virginianus) population and habitat ecology employ use of radio-telemetry techniques to relocate and monitor individuals. Radio-telemetry enables estimation of reproductive success, survival, movements, and home range at levels of resolution not otherwise possible. Unbiased estimation of these parameters via radio-telemetry assumes that survival, reproduction, and behavior of radio-marked individuals are not affected by carrying the radio-transmitter. These assumptions have not been rigorously tested for bobwhites. In 1993, we initiated a study at Divide Section Wildlife Management Area in Mississippi and at Tall Timbers Research Station to test the effects of radio-transmitters on survival, harvest rate, and body condition of bobwhites. From 1993 to 1996 we banded 221 and radio-marked 259 bobwhites on Tall Timbers Research Station. Harvest rate for radio-marked bobwhites was 18.5% and banded birds 12.7%. In 2 of 3 years, radio-marked birds experienced greater mean weight loss between capture and harvest than banded birds. From 1994 to 1995 we radio marked 188 and banded 210 birds on Divide Section Wildlife Management Area. Harvest rate for radio-marked birds was 40% and banded birds 30%. In the 1995-1996 hunting season radiomarked birds had lower mean weight gain from capture to harvest than banded birds. Based on our sample of marked birds, 34% of the fall population on this area was harvested. We have established a captive breeding colony of wild bobwhites at the Blackjack Captive Animal Research Facility at Mississippi State University. During the summer of 1996, genetically wild progeny are being produced to be used in a pen study to evaluate the effects of radio-transmitters on bobwhite body weight and lipid levels under abundant and scarce food resources. This study will provide the first harvest rate estimates for bobwhites on a public hunting area in Mississippi. Additionally, this study will evaluate the effects of radio-transmitters on bobwhite body condition, survival, and harvest rate. It will either validate the assumption of no radio effects and aid interpretation of previous and future radio studies or elucidate critical violations of fundamental assumptions of this methodology. If radio effects are detected, this study will identify the specific mechanisms creating bias in estimation of population parameters. This information will enable researchers to target radio design problems and develop new radio technology with reduced effects. Preliminary results suggest that radio-marking may marginally increase bobwhite vulnerability to harvest and potentially predation

Complex genital system of a haplogyne spider (Arachnida, Araneae, Tetrablemmidae) indicates internal fertilization and full female control over transferred sperm.

The female genital organs of the tetrablemmid Indicoblemma lannaianum are astonishingly complex. The copulatory orifice lies anterior to the opening of the uterus externus and leads into a narrow insertion duct that ends in a genital cavity. The genital cavity continues laterally in paired tube-like copulatory ducts, which lead into paired, large, sac-like receptacula. Each receptaculum has a sclerotized pore plate with associated gland cells. Paired small fertilization ducts originate in the receptacula and take their curved course inside the copulatory ducts. The fertilization ducts end in slit-like openings in the sclerotized posterior walls of the copulatory ducts. Huge masses of secretions forming large balls are detectable in the female receptacula. An important function of these secretory balls seems to be the encapsulation of spermatozoa in discrete packages in order to avoid the mixing of sperm from different males. In this way, sperm competition may be completely prevented or at least severely limited. Females seem to have full control over transferred sperm and be able to express preference for spermatozoa of certain males. The lumen of the sperm containing secretory balls is connected with the fertilization duct. Activated spermatozoa are only found in the uterus internus of females, which is an indication of internal fertilization. The sperm cells in the uterus internus are characterized by an extensive cytoplasm and an elongated, cone-shaped nucleus. The male genital system of I. lannaianum consists of thick testes and thin convoluted vasa deferentia that open into the wide ductus ejaculatorius. The voluminous globular palpal bulb is filled with seminal fluid consisting of a globular secretion in which only a few spermatozoa are embedded. The spermatozoa are encapsulated by a sheath produced in the genital system. The secretions in females may at least partly consist of male secretions that could be involved in the building of the secretory balls or play a role in sperm activation. The male secretions could also afford nutriments to the spermatozoa