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The distribution of Transverse Aeolian Ridges on Mars
Abstract not available
Capturing Hiproofs in HOL Light
Hierarchical proof trees (hiproofs for short) add structure to ordinary proof
trees, by allowing portions of trees to be hierarchically nested. The
additional structure can be used to abstract away from details, or to label
particular portions to explain their purpose. In this paper we present two
complementary methods for capturing hiproofs in HOL Light, along with a tool to
produce web-based visualisations. The first method uses tactic recording, by
modifying tactics to record their arguments and construct a hierarchical tree;
this allows a tactic proof script to be modified. The second method uses proof
recording, which extends the HOL Light kernel to record hierachical proof trees
alongside theorems. This method is less invasive, but requires care to manage
the size of the recorded objects. We have implemented both methods, resulting
in two systems: Tactician and HipCam
Acquired immune heterogeneity and its sources in human helminth infection
Similarities in the immunobiology of different parasitic worm infections indicate that co-evolution of humans and helminths has shaped a common anti-helminth immune response. However, recent in vitro and immuno-epidemiological studies highlight fundamental differences and plasticity within host-helminth interactions. The ‘trade-off’ between immunity and immunopathology inherent in host immune responses occurs on a background of genetic polymorphism, variable exposure patterns and infection history. For the parasite, variation in life-cycle and antigen expression can influence the effector responses directed against them. This is particularly apparent when comparing gastrointestinal and tissue-dwelling helminths. Furthermore, insights into the impact of anti-helminthic treatment and co-infection on acquired immunity suggest that immune heterogeneity arises not from hosts and parasites in isolation, but also from the environment in which immune responses develop. Large-scale differences observed in the epidemiology of human helminthiases are a product of complex host-parasite-environment interactions which, given potential for exposure to parasite antigens in utero, can arise even before a parasite interacts with its human host. This review summarizes key differences identified in human acquired immune responses to nematode and trematode infections of public health importance and explores the factors contributing to these variations
SEASONALITY OF BIRD STRIKES: TOWARDS A BEHAVIOURAL EXPLANATION
It is well known that, at least in the Northern Hemisphere, there is a strong seasonal element in the annual pattern of bird strikes. This study undertakes a statistical analysis of an 11year data set collected at Dublin Airport, Ireland. It attempts to identify statistically significant trends in the seasonal trajectories of bird strikes, both in general and in respect of individual species and in comparison with seasonal trends in the abundance of birds generally and at Dublin Airport in particular. Hypotheses relating to the idea of “open” (i.e. intervals of through-put of naïve and young birds) and “closed” (i.e. intervals when throughput is declining or at a minimum) periods are tested. The results are discussed in the context of the probable ability of birds to learn to avoid aircraft. If birds possess a spatio-temporal memory then it is likely that this ability, or the lack of it, may explain some of the observed trends in the seasonal distribution of bird strikes
On the Identification of High Mass Star Forming Regions using IRAS: Contamination by Low-Mass Protostars
We present the results of a survey of a small sample (14) of low-mass
protostars (L_IR < 10^3 Lsun) for 6.7 GHz methanol maser emission performed
using the ATNF Parkes radio telescope. No new masers were discovered. We find
that the lower luminosity limit for maser emission is near 10^3 Lsun, by
comparison of the sources in our sample with previously detected methanol maser
sources. We examine the IRAS properties of our sample and compare them with
sources previously observed for methanol maser emission, almost all of which
satisfy the Wood & Churchwell criterion for selecting candidate UCHII regions.
We find that about half of our sample satisfy this criterion, and in addition
almost all of this subgroup have integrated fluxes between 25 and 60 microns
that are similar to sources with detectable methanol maser emission. By
identifying a number of low-mass protostars in this work and from the
literature that satisfy the Wood & Churchwell criterion for candidate UCHII
regions, we show conclusively for the first time that the fainter flux end of
their sample is contaminated by lower-mass non-ionizing sources, confirming the
suggestion by van der Walt and Ramesh & Sridharan.Comment: 8 pages with 2 figures. Accepted by Ap
High incidence of thrombophilia detected in Chinese patients with venous thrombosis
Venous thromboembolism is rare in Chinese. To determine the incidence and disease profile of thrombophilia in Chinese patients with thrombosis, 52 unselected Chinese patients with documented venous thrombosis were studied for the presence of thrombophilia. Levels of antithrombin III (AT III), protein C (PC) and protein S (PS) as well as the presence of acquired lupus anticoagulant (LA) and anticardiolipin antibody (ACA) were investigated. Thirty patients were found to be abnormal. These consisted of 5 AT III deficiencies, 9 PC deficiencies, 10 PS deficiencies, 1 combined PC and PS deficiency (all in the heterozygous range), and 5 patients with LA and/or ACA. When the patients with LA and/or ACA are excluded, the incidence of hereditary thrombophilia is 25/47 i.e. 53.2% which is much higher than those reported in studies of Caucasian patients selected under strict criteria. Family studies performed in 16 cases of hereditary thrombophilia revealed involvement in 11 cases (68.7%); a total of 36 heterozygous family members were affected, most of which remain asymptomatic. Although 35 events predisposing to thrombosis (27 pregnancies, 1 oral contraceptive consumption and 7 surgical operations) were identified among these index patients, and the heterozygous family members, thrombosis was observed on only 6 occasions (17.1%). The data suggest that pregnancy and surgery do not carry the same degree of thrombotic risk in Chinese as in the Caucasian population with heterozygous AT III, PC and PS deficiency.published_or_final_versio
The CO Molecular Outflows of IRAS 16293-2422 Probed by the Submillimeter Array
We have mapped the proto-binary source IRAS 16293-2422 in CO 2-1, 13CO 2-1,
and CO 3-2 with the Submillimeter Array (SMA). The maps with resolution of
1".5-5" reveal a single small scale (~3000 AU) bipolar molecular outflow along
the east-west direction. We found that the blueshifted emission of this small
scale outflow mainly extends to the east and the redshifted emission to the
west from the position of IRAS 16293A. A comparison with the morphology of the
large scale outflows previously observed by single-dish telescopes at
millimeter wavelengths suggests that the small scale outflow may be the inner
part of the large scale (~15000 AU) E-W outflow. On the other hand, there is no
clear counterpart of the large scale NE-SW outflow in our SMA maps. Comparing
analytical models to the data suggests that the morphology and kinematics of
the small scale outflow can be explained by a wide-angle wind with an
inclination angle of ~30-40 degrees with respect to the plane of the sky. The
high resolution CO maps show that there are two compact, bright spots in the
blueshifted velocity range. An LVG analysis shows that the one located 1" to
the east of source A is extremely dense, n(H_2)~10^7 cm^-3, and warm, T_kin >55
K. The other one located 1" southeast of source B has a higher temperature of
T_kin >65 K but slightly lower density of n(H_2)~10^6 cm^-3. It is likely that
these bright spots are associated with the hot core-like emission observed
toward IRAS 16293. Since both two bright spots are blueshifted from the
systemic velocity and are offset from the protostellar positions, they are
likely formed by shocks.Comment: 27 pages, 8 figures, accepted for publication in ApJ, minor typos
correcte
A Catalogue of Optically Selected Cores
We present a new catalogue of 406 dense cores optically selected by using the
STScI Digitized Sky Survey (DSS). In this catalogue 306 cores have neither an
Embedded YSO (EYSO) nor a Pre-Main-Sequence (PMS) star, 94 cores have EYSOs (1
core has both an EYSO and a PMS star), and 6 cores have PMS star only. Our
sample of dense cores in the catalogue is fairly complete within a category of
northern Lynds class 5, 6 clouds, and southern Hartley et al. (1986)'s class A
clouds, providing a database useful for the systematic study of dense cores.
Most of the cores listed in the catalogue have diameters between
pc with a mean of pc. The sizes ( pc in the mean) of
cores with EYSOs are found to be usually larger than the sizes ( pc
in the mean) of starless cores. The typical mean gas density of the cores is
. Most of the cores are more likely elongated than
spherical (mean aspect ratio: ). The ratio of the number of cores
with EYSOs to the number of starless cores for our sample is about 0.3,
suggesting that the typical lifetime of starless cores is Myr, about
3 times longer than the duration of the Class 0 and Class I phases. This
lifetime is shorter than expected from models of ambipolar diffusion, by
factors of 2-44.Comment: 22 pages, 8 figures, 3 tables, and to appear in ApJS.
Harvard-Smithsonian Center for Astrophysic
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