Aggregation of SiC-X Grains in Supernova Ejecta

We present a model for the formation of silicon carbide aggregates within the expanding and cooling supernova remnant. Many SiC-X grains have been found to be aggregates of smaller crystals which are isotopically homogenous. The initial condensation of SiC in the ejecta occurs within a interior dense shell of material which is created by a reverse shock which rebounds from the core-envelope interface. A subsequent reverse shock accelerates the grains forward, but the gas drag from the ejecta on the rapidly moving particles limits their travel distance. By observing the effects of gas drag on the travel distance of grains, we propose that supernova grain aggregates form from material that condensed in a highly localized region, which satisfies the observational evidence of isotopic homogeneity in SiC-X grains.Comment: 9 pages, 5 figures, To be published in the Astrophysical Journa

Effects of crude protein levels in concentrate supplements on animal performance and nitrogen utilization of lactating dairy cows fed fresh-cut perennial grass

There are increased concerns regarding N pollution of air and ground water from grazing cattle. Although a number of studies have investigated mitigation strategies for N output from dairy cows fed conserved forages and concentrates, similar research on fresh-cut grass in addition to production parameters is limited. Therefore the current study, using 3 dietary treatments and incorporating 2 genotypes, was designed to evaluate the effects of concentrate crude protein (CP) level on animal production and N utilization efficiency (NUE) of lactating dairy cows. Twelve multiparous cows (6 Holstein and 6 Holstein × Swedish Red) were used in a change-over study with three 25-d periods and 3 diet treatments; low, medium and high CP concentrate (14.1, 16.1 and 18.1% respectively, dry matter (DM) basis) fed at 32.8% DM intake in combination with good quality zero-grazed perennial ryegrass (18.2% CP, DM basis). Each period consisted of an adaption phase (18-d) housed as a single group, 1-d adaption in individual stalls and a 6-d measurement phase with feed intake and feces, urine and milk output recorded. There was no significant interaction between cow genotype and concentrate CP level on any animal performance or NUE parameters. Total DM intake, milk yield and composition and NUE were not affected by dietary treatment. However, increasing concentrate CP level increased (i) N intake by 42 g/d and excretion in urine and manure, by 38 and 40 g/d, respectively, and (ii) the ratio of urine N over manure N. Feeding high CP, rather than low CP concentrate, increased milk urea N (MUN) content by 3.6 mg/dL and total MUN output by 1.08 g/d. Crossbred cows had lower grass DM intake, total DM intake, total N intake and consequently energy-corrected milk yield. However, cow genotype had no significant effect on NUE or MUN parameters. Equations have been developed to predict urine N excretion using MUN output as sole predictor or in combination with dietary CP level. The present study indicated that when grazing cows are fed on good quality pasture, feeding concentrates with a protein content as low as 14.1% may not negatively affect productivity. In addition, reducing concentrate CP concentration may be a successful method of reducing urinary N excretion of lactating dairy cattle on pasture-based systems, but further research is needed to investigate long-term effects of supplementary concentrate CP content on milk production

The Role of Overexpressed HER2 in Transformation

The HER family of receptors has an important role in the network of cell signals controlling cell growth and differentiation. Although the activity of the HER receptor is strictly controlled in normal cells, HER2 receptor overexpression plays a pivotal role in transformation and tumorigenesis. HER2 gene amplification and/or overexpression of the receptor has been detected in subsets of a wide range of human cancers including breast cancer, and is an indicator of poor prognosis. It is proposed that overexpressed HER2 in combination with HER3 causes high activity of cell-signaling networks, thereby resulting in tumor cell proliferation. Thus, the HER2 receptor is an attractive target for new anti-cancer treatments. Mono-clonal antibodies directed against the receptor are the most promising of these, and the humanized anti-HER2 monoclonal antibody trastuzumab (Herceptin) has shown significant clinical efficacy in clinical trials. The anti-tumor mechanisms of anti-HER2 monoclonal antibodies are not completely understood. However, some tumor types are not sensitive to trastuzumab, suggesting that the response of a tumor to trastuzumab may not only be dependent on overexpressed HER2, but may also be influenced by other members of the HER receptor family expressed in the tumor cel

Modulation of p27/Cdk2 complex formation through 4D5-mediated inhibition of HER2 receptor signaling

The molecular mechanisms mediating the anti-proliferative effects of the murine anti-HER2 monoclonal antibody (4D5) were investigated in HER2-overexpressing human carcinoma cell lines. Treatment with 4D5 resulted in a dramatic accumulation of BT-474 breast carcinoma cells in Gl; concomitant with reduced expression of proteins involved in sequestration of the cyclin E/Cdk2 inhibitor protein p27, increased association of p27 with Cdk2 complexes and Cdk2 inactivation. No equivalent effects were observed in BT-474 cells treated with a control, non-inhibitory HER2 monoclonal antibody (FRP5) or in a HER2-overexpressing cell line insensitive to 4D5 treatment (MKN7 gastric carcinoma cells), confirming the relationship between these molecular changes and 4D5-mediated inhibition of proliferation. Increased p27 expression was also observed in 4D5-treated BT-474 cells; however an antisense approach demonstrated that this increase was not required for Cdk2 inactivation or establishment of the Gl block. These data suggest that 4D5 interferes with HER2 receptor signaling, resulting in downregulation of proteins involved in p27 sequestration. This causes release of p27, allowing binding and inhibition of cyclin E/Cdk2 complexes and inhibition of Gl/S progression. This model was confirmed using a second 4D5-sensitive, HER2-overexpressing breast tumor line (SKBR3), and suggests that the dependency of a given tumor cell on elevated HER2-receptor signaling for the maintenance of p27 sequestration proteins may determine the clinical response to treatment with the humanized anti-HER2 monoclonal antibody Herceptin® (trastuzumab

Endovascular Management of Traumatic Iliac Vessel Disruption—Report of Two Cases

AbstractVascular injuries in a multi-trauma patient are associated with significant cardiovascular instability and organ injury. Injuries with active bleeding are best treated with a quick, safe and the least less invasive procedure available to the trauma surgeon. We report two cases of blunt trauma induced common and external iliac vessel injury, managed by endovascular treatment. In the second case, endovascular treatment prevented histological examination of the artery, which would have revealed an alternative diagnosis

Asymptomatic Primary Fallopian Tube Cancer: An Unusual Cause of Axillary Lymphadenopathy

Primary Fallopian tube malignancy is considered a rare disease and is often mistaken histologically and clinically for ovarian cancer. The etiology is poorly understood, and it typically presents at an advanced disease stage, as symptoms are often absent in the initial period. As a result, primary fallopian tube cancer is generally associated with a poor prognosis. We present the case of a 45-year-old female who presents with a 5-day history of left axillary swelling and a normal breast examination. Mammogram and biopsy of a lesion in the left breast revealed a fibroadenoma but no other abnormalities. Initial sampling of the axillary node was suspicious for a primary breast malignancy, but histology of the excised node refuted this. PET-CT showed an area of high uptake in the right pelvis, and a laparoscopy identified a tumor of the left fallopian tube which was subsequently excised and confirmed as a serous adenocarcinoma

Pleasure and pedagogy: the consumption of DVD add-ons among Irish teenagers

This article addresses the issue of young people and media use in the digital age, more specifically the interconnection between new media pleasures and pedagogy as they relate to the consumption of DVD add-ons. Arguing against the view of new media as having predominantly detrimental effects on young people, the authors claim that new media can enable young people to develop media literacy skills and are of the view that media literacy strategies must be based on an understanding and legitimating of young people's use patterns and pleasures. The discussion is based on a pilot research project on the use patterns and pleasures of use with a sample of Irish teenagers. They found that DVDs were used predominantly in the home context, and that, while there was variability in use between the groups, overall they developed critical literacy skills and competences which were interwoven into their social life and projects of identity construction. The authors suggest that these findings could be used to develop DVDs and their add-on features as a learning resource in the more formal educational setting and they go on to outline the potential teaching benefits of their use across a range of pedagogical areas

Modeling the Low State Spectrum of the X-Ray Nova XTE J1118+480

Based on recent multiwavelength observations of the new X-ray nova XTE J1118+480, we can place strong constraints on the geometry of the accretion flow in which a low/hard state spectrum, characteristic of an accreting black hole binary, is produced. We argue that the absence of any soft blackbody-like component in the X-ray band implies the existence of an extended hot optically-thin region, with the optically-thick cool disk truncated at some radius R_{tr} > 55 R_{Schw}. We show that such a model can indeed reproduce the main features of the observed spectrum: the relatively high optical to X-ray ratio, the sharp downturn in the far UV band and the hard X-ray spectrum. The absence of the disk blackbody component also underscores the requirement that the seed photons for thermal Comptonization be produced locally in the hot flow, e.g. via synchrotron radiation. We attribute the observed spectral break at 2 keV to absorption in a warm, partially ionized gas.Comment: 6 pages, including 1 figure; LaTeX (emulateapj5.sty), to appear in Ap

Distribution and abundance of fish and crayfish in a Waikato stream in relation to basin area

The aim of this study was to relate the longitudinal distribution of fish and crayfish to increasing basin area and physical site characteristics in the Mangaotama Stream, Waikato region, North Island, New Zealand. Fish and crayfish were captured with two-pass removal electroshocking at 11 sites located in hill-country with pasture, native forest, and mixed land uses within the 21.6 km2 basin. Number of fish species and lineal biomass of fish increased with increasing basin area, but barriers to upstream fish migration also influenced fish distribution; only climbing and non-migratory species were present above a series of small waterfalls. Fish biomass increased in direct proportion to stream width, suggesting that fish used much of the available channel, and stream width was closely related to basin area. Conversely, the abundance of crayfish was related to the amount of edge habitat, and therefore crayfish did not increase in abundance as basin area increased. Densities of all fish species combined ranged from 17 to 459 fish 100 m-2, and biomass ranged from 14 to 206 g m-2. Eels dominated the fish assemblages, comprising 85-100% of the total biomass; longfinned eels the majority of the biomass at most sites. Despite the open access of the lower sites to introduced brown trout, native species dominated all the fish communities sampled