765 research outputs found
Management of super-refractory status epilepticus with isoflurane and hypothermia
Super-refractory status epilepticus (SRSE) is defined as status epilepticus that continues 24 h or more after the onset of anesthesia, and includes those cases in which epilepsy is recurrent upon treatment reduction. We describe the presentation and successful management of a male patient with SRSE using the inhaled anesthetic isoflurane, and mild hypothermia (HT). The potential utility of combined HT and volatile anesthesia is discussed
Novel Small Molecule Inhibitors of Cancer Stem Cell Signaling Pathways
The main aim of oncologists worldwide is to understand and then intervene in the primary tumor initiation and propagation mechanisms. This is essential to allow targeted elimination of cancer cells without altering normal mitotic cells. Currently, there are two main rival theories describing the process of tumorigenesis. According to the Stochastic Model, potentially any cell, once defunct, is capable of initiating carcinogenesis. Alternatively the Cancer Stem Cell (CSC) Model posits that only a small fraction of undifferentiated tumor cells are capable of triggering carcinogenesis. Like healthy stem cells, CSCs are also characterized by a capacity for self-renewal and the ability to generate differentiated progeny, possibly mediating treatment resistance, thus leading to tumor recurrence and metastasis. Moreover, molecular signaling profiles are similar between CSCs and normal stem cells, including Wnt, Notch and Hedgehog pathways. Therefore, development of novel chemotherapeutic agents and proteins (e.g., enzymes and antibodies) specifically targeting CSCs are attractive pharmaceutical candidates. This article describes small molecule inhibitors of stem cell pathways Wnt, Notch and Hedgehog, and their recent chemotherapy clinical trials
Climate-related long-term faunal changes in a California rocky intertidal community [abstract]
EXTRACT (SEE PDF FOR FULL ABSTRACT):
The effects of gradual climate change (ie, multi-decadal) on biological communities are not well understood for most natural systems, owing principally to the lack of quantitative observations in early studies. ... We resurveyed invertebrate species on an intertidal transect in central California, first established and surveyed in 1931, to assess shifts in community structure
Top soil physical and chemical properties in Kazakhstan across a north-south gradient
Kazakhstan’s soil properties have yet to be comprehensively characterized. We sampled 40 sites consisting of ten major soil types at spring (wet) and late-summer (dry) seasons. The sample locations range from semi-arid to arid with an annual mean air temperature from 1.2 to 10.7 °C and annual precipitation from less than 200 to around 400 mm. Overall topsoil total (STC), organic (SOC), and inorganic (SIC) carbon did not change significantly between spring and late summer. STC and SOC show a wave like pattern from north to south with two maxima in northern and southern Kazakhstan and one minimum in central Kazakhstan. With a few exceptions SIC content at northern sites is generally low, whereas at Lake Balkhash SIC can exceed 75% of STC. Independent of the seasons, SOC significantly differed among soil types. Total nitrogen content distribution among our sampling sites followed a similar pattern as SOC with significant differences between soil types occurring in northern, central and southern Kazakhstan
Ward Identities, B-> \rho Form Factors and |V_ub|
The exclusive FCNC beauty semileptonic decay B-> \rho is studied using Ward
identities in a general vector meson dominance framework, predicting vector
meson couplings involved. The long distance contributions are discussed which
results to obtain form factors and |V_ub|. A detailed comparison is given with
other approaches.Comment: 30 pages+four postscript figures, an Appendix adde
Two Higgs Bi-doublet Left-Right Model With Spontaneous P and CP Violation
A left-right symmetric model with two Higgs bi-doublet is shown to be a
consistent model for both spontaneous P and CP violation. The flavor changing
neutral currents can be suppressed by the mechanism of approximate global U(1)
family symmetry. We calculate the constraints from neural meson mass
difference and demonstrate that a right-handed gauge boson
contribution in box-diagrams with mass well below 1 TeV is allowed due to a
cancellation caused by a light charged Higgs boson with a mass range GeV. The contribution to can be suppressed from
appropriate choice of additional CP phases appearing in the right-handed
Cabbibo-Kobayashi-Maskawa matrix. The model is also found to be fully
consistent with mass difference , and the mixing-induced CP
violation quantity , which is usually difficult for the
model with only one Higgs bi-doublet. The new physics beyond the standard model
can be directly searched at the colliders LHC and ILC.Comment: 25 pages, 6 figures, typos corrected, 1 figure added, published
versio
Combining functional weed ecology and crop stable isotope ratios to identify cultivation intensity: a comparison of cereal production regimes in Haute Provence, France and Asturias, Spain
This investigation combines two independent
methods of identifying crop growing conditions and husbandry
practices—functional weed ecology and crop stable
carbon and nitrogen isotope analysis—in order to assess
their potential for inferring the intensity of past cereal
production systems using archaeobotanical assemblages.
Present-day organic cereal farming in Haute Provence,
France features crop varieties adapted to low-nutrient soils
managed through crop rotation, with little to no manuring.
Weed quadrat survey of 60 crop field transects in this region
revealed that floristic variation primarily reflects
geographical differences. Functional ecological weed data
clearly distinguish the Provence fields from those surveyed
in a previous study of intensively managed spelt wheat in
Asturias, north-western Spain: as expected, weed ecological
data reflect higher soil fertility and disturbance in
Asturias. Similarly, crop stable nitrogen isotope values
distinguish between intensive manuring in Asturias and
long-term cultivation with minimal manuring in Haute
Provence. The new model of cereal cultivation intensity
based on weed ecology and crop isotope values in Haute
Provence and Asturias was tested through application to
two other present-day regimes, successfully identifying a
high-intensity regime in the Sighisoara region, Romania,
and low-intensity production in Kastamonu, Turkey. Application
of this new model to Neolithic archaeobotanical
assemblages in central Europe suggests that early farming
tended to be intensive, and likely incorporated manuring,
but also exhibited considerable variation, providing a finer
grained understanding of cultivation intensity than previously
available
Predictions for b -> ssdbar, ddsbar decays in the SM and with new physics
The b -> ssdbar and b -> ddsbar decays are highly suppressed in the SM, and
are thus good probes of new physics (NP) effects. We discuss in detail the
structure of the relevant SM effective Hamiltonian pointing out the presence of
nonlocal contributions which can be about \lambda^{-4} (m_c^2/m_t^2) ~ 30% of
the local operators (\lambda = 0.21 is the Cabibbo angle). The matrix elements
of the local operators are computed with little hadronic uncertainty by
relating them through flavor SU(3) to the observed \Delta S = 0 decays. We
identify a general NP mechanism which can lead to the branching fractions of
the b\to ss\bar d modes at or just below the present experimental bounds, while
satisfying the bounds from K-Kbar and B_{(s)}-Bbar_{(s)} mixing. It involves
the exchange of a NP field carrying a conserved charge, broken only by its
flavor couplings. The size of branching fractions within MFV, NMFV and general
flavor violating NP are also predicted. We show that in the future energy
scales higher than 10^3 TeV could be probed without hadronic uncertainties even
for b-> s and b-> d transitions, if enough statistics becomes available.Comment: 30 pages, one eps figur
Secondary organic aerosol (SOA) yields from NO_3 radical + isoprene based on nighttime aircraft power plant plume transects
Nighttime reaction of nitrate radicals (NO_3) with biogenic volatile organic compounds (BVOC) has been proposed as a potentially important but also highly uncertain source of secondary organic aerosol (SOA). The southeastern United States has both high BVOC and nitrogen oxide (NO_x) emissions, resulting in a large model-predicted NO_3-BVOC source of SOA. Coal-fired power plants in this region constitute substantial NO_x emissions point sources into a nighttime atmosphere characterized by high regionally widespread concentrations of isoprene. In this paper, we exploit nighttime aircraft observations of these power plant plumes, in which NO_3 radicals rapidly remove isoprene, to obtain field-based estimates of the secondary organic aerosol yield from NO_3+isoprene. Observed in-plume increases in nitrate aerosol are consistent with organic nitrate aerosol production from NO_3+isoprene, and these are used to determine molar SOA yields, for which the average over nine plumes is 9% (±5%). Corresponding mass yields depend on the assumed molecular formula for isoprene-NO_3-SOA, but the average over nine plumes is 27% (±14%), on average larger than those previously measured in chamber studies (12%–14% mass yield as ΔOA∕ΔVOC after oxidation of both double bonds). Yields are larger for longer plume ages. This suggests that ambient aging processes lead more effectively to condensable material than typical chamber conditions allow. We discuss potential mechanistic explanations for this difference, including longer ambient peroxy radical lifetimes and heterogeneous reactions of NO_3-isoprene gas phase products. More in-depth studies are needed to better understand the aerosol yield and oxidation mechanism of NO_3 radical+isoprene, a coupled anthropogenic–biogenic source of SOA that may be regionally significant
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