1,933 research outputs found
Comparison of energy consumption and costs of different HEVs and PHEVs in European and American context
This paper will analyse on the one hand the potential of Plug in Hybrid electric Vehicles to significantly reduce fuel consumption and displace it torward various primary energies thanks to the electricity sector. On the other hand the total cost of ownership of two different PHEV architectures will be compared to a conventional cehicle and a HEV without external charging
A Study on High Performance Fine-Grained Concrete Containing Rice Husk Ash
Rice husk ash (RHA) is classified as a highly reactive pozzolan. It has a very high silica content similar to that of silica fume (SF). Using less-expensive and locally available RHA as a mineral admixture in concrete brings ample benefits to the costs, the technical properties of concrete as well as to the environment. An experimental study of the effect of RHA blending on workability, strength and durability of high performance fine-grained concrete (HPFGC) is presented. The results show that the addition of RHA to HPFGC improved significantly compressive strength, splitting tensile strength and chloride penetration resistance. Interestingly, the ratio of compressive strength to splitting tensile strength of HPFGC was lower than that of ordinary concrete, especially for the concrete made with 20 % RHA. Compressive strength and splitting tensile strength of HPFGC containing RHA was similar and slightly higher, respectively, than for HPFGC containing SF. Chloride penetration resistance of HPFGC containing 10–15 % RHA was comparable with that of HPFGC containing 10 % SF
Erlotinib in patients with previously irradiated, recurrent brain metastases from non-small cell lung cancer: Two case reports
Background: With the current improvements in primary lung care, the long-term control of brain metastases becomes a clinical challenge. No established therapeutic approaches exist for cranial relapse after response to previous radiotherapy and systemic therapy. Tyrosine kinase inhibitors like erlotinib with its proven activity in non-small cell lung cancer may provide clinical benefits in such patients. Patients and Methods: Two case reports are presented illustrating the efficacy of erlotinib in patients with recurrent brain metastases and parallel thoracic progression. Results: Both patients showed lasting partial remissions in the brain and lung, and clinical symptom improvement. Conclusion: The observed survival times of above 18 and 15 months, respectively, since occurrence of cranial disease manifestation in line with the achieved progression-free survival times of 9 and 6 months by the erlotinib third-line therapy are remarkable. The use of targeted therapies after whole-brain irradiation should be investigated more systematically in prospective clinical trials
GeV emission from Gamma Ray Bursts: a radiative fireball?
We study the emission observed at energies greater than 100 MeV of 11 Gamma
Ray Bursts (GRBs) detected by the Fermi/Large Area Telescope (LAT) until
October 2009. The GeV emission has three main properties: (i) its duration is
often longer than the duration of the softer emission detected by the Gamma
Burst Monitor (GBM) onboard Fermi [this confirms earlier results from the
Energetic Gamma-Ray Experiment Telescope (EGRET)]; (ii) its spectrum is
consistent with F(v) propto v^(-1) and does not show strong spectral evolution;
(iii) for the brightest bursts, the flux detected by the LAT decays as a power
law with a typical slope: t^(-1.5). We argue that the observed >0.1 GeV flux
can be interpreted as afterglow emission shortly following the start of the
prompt phase emission as seen at smaller frequencies. The decay slope is what
expected if the fireball emission is produced in the radiative regime, i.e. all
dissipated energy is radiated away. We also argue that the detectability in the
GeV energy range depends on the bulk Lorentz factor Gamma of the bursts, being
strongly favoured in the case of large Gamma. This implies that the fraction of
bursts detected at high energies corresponds to the fraction of bursts having
the largest Gamma. The radiative interpretation can help to explain why the
observed X-ray and optical afterglow energetics are much smaller than the
energetics emitted during the prompt phase, despite the fact that the collision
with the external medium should be more efficient than internal shocks in
producing the radiation we see.Comment: 12 pages, 9 figures, accepted for publication in MNRAS, minor
changes, added EGRET light-curve of GRB 94021
Limits on the GeV Emission from Gamma-Ray Bursts
The Large Area Telescope (LAT) on board of the Fermi satellite detected
emission above 30 MeV only in a small fraction of the long gamma-ray bursts
(GRBs) detected by the Fermi Gamma-ray Burst Monitor (GBM) at 8 keV - 10 MeV.
Those bursts that were detected by the LAT were among the brightest GBM bursts.
We examine a sample of the most luminous GBM bursts with no LAT detection and
obtain upper limits on their high energy fluence. We find an average upper
limit of LAT/GBM fluence ratio of 0.13 for GeV fluence during and an
average upper limit ratio of 0.45 for GeV fluence during the first 600 seconds
after the trigger. These ratios strongly constrain various emission models and
in particular rule out SSC models for the prompt emission. In about a third of
both LAT detected and LAT non-detected bursts, we find that the extrapolation
of the MeV range Band spectrum to the GeV range is larger than the observed GeV
fluence (or its upper limit). While this excess is not highly significant for
any specific burst, the overall excess in a large fraction of the bursts
suggests a decline in the high energy spectral slope in at least some of these
bursts. Possibly an evidence for the long sought after pair creation limit.Comment: Accepted for publication in MNRA
Multiple immune abnormalities in tumor necrosis factor and lymphotoxin-α double-deficient mice
To investigate the roles of tumor necrosis factor (TNF) and lymphotoxin (LT)-α in the development and function of the immune system, the Tnf and Ltα genes were simultaneously inactivated in mice by homologous recombination. These mutant mice are highly susceptible to Listeria monocytogenes infection and resistant to endotoxic shock induced by the combined administration of D-galactosamine (D-GaIN) and lipopolysaccharide (LPS). Their splenic microarchitecture is disorganized, characterized by the loss of the clearly defined marginal zone, ill defined T and B cell areas, and absence of MAdCAM-1 and reduced ICAM-1, VCAM-1 and Mac-1 expression. They are devoid of peripheral lymph nodes and Peyer's patches, and show a strong reduction of lgA+ plasma cells in the intestinal lamina propria. The alymphoplasia is accompanied by a marked B lymphocytosis and reduced basal Ig levels. Ig depositions in the renal glomerulus and a strong up-regulation of MHC class I antigen expression on endothelial cells of different tissues are observed. The primary humoral immune response towards sheep red blood cells reveals a defective IgG isotype switch, while that against vescicular stomatitis virus is normal. The cytotoxic T cell responses are attenuated, although still effective, against vaccinia, lymphocytic choriomeningitis virus (LCMV-ARM) and LCMV-WE. In conclusion, the combined inactivation of Tnf and Ltα confirms their essential role in the normal development and function of the immune syste
DNA strand break repair and neurodegeneration.
A number of DNA repair disorders are known to cause neurological problems. These disorders can be broadly characterised into early developmental, mid-to-late developmental or progressive. The exact developmental processes that are affected can influence disease pathology, with symptoms ranging from early embryonic lethality to late-onset ataxia. The category these diseases belong to depends on the frequency of lesions arising in the brain, the role of the defective repair pathway, and the nature of the mutation within the patient. Using observations from patients and transgenic mice, we discuss the importance of double strand break repair during neuroprogenitor proliferation and brain development and the repair of single stranded lesions in neuronal function and maintenance
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