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Future Needs in Mast Cell Biology.
The pathophysiological roles of mast cells are still not fully understood, over 140 years since their description by Paul Ehrlich in 1878. Initial studies have attempted to identify distinct "subpopulations" of mast cells based on a relatively small number of biochemical characteristics. More recently, "subtypes" of mast cells have been described based on the analysis of transcriptomes of anatomically distinct mouse mast cell populations. Although mast cells can potently alter homeostasis, in certain circumstances, these cells can also contribute to the restoration of homeostasis. Both solid and hematologic tumors are associated with the accumulation of peritumoral and/or intratumoral mast cells, suggesting that these cells can help to promote and/or limit tumorigenesis. We suggest that at least two major subsets of mast cells, MC1 (meaning anti-tumorigenic) and MC2 (meaning pro-tumorigenic), and/or different mast cell mediators derived from otherwise similar cells, could play distinct or even opposite roles in tumorigenesis. Mast cells are also strategically located in the human myocardium, in atherosclerotic plaques, in close proximity to nerves and in the aortic valve. Recent studies have revealed evidence that cardiac mast cells can participate both in physiological and pathological processes in the heart. It seems likely that different subsets of mast cells, like those of cardiac macrophages, can exert distinct, even opposite, effects in different pathophysiological processes in the heart. In this chapter, we have commented on possible future needs of the ongoing efforts to identify the diverse functions of mast cells in health and disease
21cm Forest with the SKA
An alternative to both the tomography technique and the power spectrum
approach is to search for the 21cm forest, that is the 21cm absorption features
against high-z radio loud sources caused by the intervening cold neutral
intergalactic medium (IGM) and collapsed structures. Although the existence of
high-z radio loud sources has not been confirmed yet, SKA-low would be the
instrument of choice to find such sources as they are expected to have spectra
steeper than their lower-z counterparts. Since the strongest absorption
features arise from small scale structures (few tens of physical kpc, or even
lower), the 21cm forest can probe the HI density power spectrum on small scales
not amenable to measurements by any other means. Also, it can be a unique probe
of the heating process and the thermal history of the early universe, as the
signal is strongly dependent on the IGM temperature. Here we show what SKA1-low
could do in terms of detecting the 21cm forest in the redshift range z =
7.5-15.Comment: Accepted for publication in the SKA Science Book 'Advancing
Astrophysics with the Square Kilometre Array', to appear in 2015; 10 pages, 5
figures; the manuscript is based on Ciardi et al., 2013, MNRAS, 428, 175
Exploration of the Current State and Directions of Dynamic Ridesharing
Dynamic ridesharing (DRS) is an emerging transportation service based on the traditional concept of shared rides. DRS makes use of web-based real-time technologies to match drivers with riders. Enabling technologies include software platforms that operate on mobile communication devices and contain location-aware capabilities including Global Positioning Systems (Agatz, Erera, Savelsberg, & Wang, 2012). The platforms are designed to provide ride-matching services via smartphone applications differing from early systems that used non-real time services such as internet forums, or telecommunications, where responses were not immediate.
The study of DRS is important when considering its role as an emerging transportation demand management strategy. DRS reduces travel demand on singleoccupancy vehicles (SOVs) by filling vehicle seats that are typically left vacant. The most recent statistics of vehicle occupancy rates were measured in 2009 by the National Household Travel Survey (NHTS), conducted by the U.S. Department of Transportation. According to the NHTS, the 2009 occupancy rate for all purposes was a meager 1.67 persons per vehicle (Federal Highway Administration, 2015). Vehicle occupancy rates examined against the total of all registered highway vehicles in the U.S. as of 2012, calculated at 253,639,386 (Bureau of Transportation Statistics, 2015), reveals the magnitude of the impact of SOVs. Left unattended, the ramifications for environmental outcomes is substantial. Among the major energy consuming sectors, transportation\u27s share is largest in terms of total CO2 emissions at 32.9% (Davis, Diegel, & Boundy, 2014, p. 11-15).
DRS offers promise to fill empty vehicle seats. Evidence indicates that specific demographic subgroups are inclined to use DRS services. For example, data suggest that the subgroup of 18 to 34-year-olds, the so-called millennials , have negative attitudes towards private car ownership unlike previous age groups (Nelson, 2013). Data collected for this study revealed that the millennial subgroup represents half of all DRS users. Millennials also revealed they tended to use DRS more than other subgroups to replace a private vehicle. Further research is needed to determine if the trend towards DRS by 18 to 34-year-olds represents current economic factors or a fundamental cultural shift away from the SOV transportation model
Direction-Dependent Polarised Primary Beams in Wide-Field Synthesis Imaging
The process of wide-field synthesis imaging is explored, with the aim of
understanding the implications of variable, polarised primary beams for
forthcoming Epoch of Reionisation experiments. These experiments seek to detect
weak signatures from redshifted 21cm emission in deep residual datasets, after
suppression and subtraction of foreground emission. Many subtraction algorithms
benefit from low side-lobes and polarisation leakage at the outset, and both of
these are intimately linked to how the polarised primary beams are handled.
Building on previous contributions from a number of authors, in which
direction-dependent corrections are incorporated into visibility gridding
kernels, we consider the special characteristics of arrays of fixed dipole
antennas operating around 100-200 MHz, looking towards instruments such as the
Square Kilometre Array (SKA) and the Hydrogen Epoch of Reionization Arrays
(HERA). We show that integrating snapshots in the image domain can help to
produce compact gridding kernels, and also reduce the need to make complicated
polarised leakage corrections during gridding. We also investigate an
alternative form for the gridding kernel that can suppress variations in the
direction-dependent weighting of gridded visibilities by 10s of dB, while
maintaining compact support.Comment: 15 pages, 4 figures. Accepted for publication in JA
Combined quantum state preparation and laser cooling of a continuous beam of cold atoms
We use two-laser optical pumping on a continuous atomic fountain in order to
prepare cold cesium atoms in the same quantum ground state. A first laser
excites the F=4 ground state to pump the atoms toward F=3 while a second
pi-polarized laser excites the F=3 -> F'=3 transition of the D2 line to produce
Zeeman pumping toward m=0. To avoid trap states, we implement the first laser
in a 2D optical lattice geometry, thereby creating polarization gradients. This
configuration has the advantage of simultaneously producing Sisyphus cooling
when the optical lattice laser is tuned between the F=4 -> F'=4 and F=4 -> F'=5
transitions of the D2 line, which is important to remove the heat produced by
optical pumping. Detuning the frequency of the second pi-polarized laser
reveals the action of a new mechanism improving both laser cooling and state
preparation efficiency. A physical interpretation of this mechanism is
discussed.Comment: Minor changes according to the recommendations of the referee: -
Corrected Fig.1. - Split the graph of Fig.6 for clarity. - Added one
reference. - Added two remarks in the conclusion. - Results unchange
High-spatial-resolution passive microwave sounding systems
During this period the emphasis was on the following: (1) further design, construction, and testing of the improved 54-GHz portion of the 54-118 GHz microwave temperature sounder (MTS) aircraft radiometer system in preparation for ER-2 observations in July 1991; and (2) final analysis and documentation of procedures for detecting and analyzing thermal waves in our 118-GHz MTS imagery. In addition, we have new unpublished measurements of dry-air attenuation at frequencies of 54 to 66 GHz and over a temperature range of 280K to 326K; these measurements should enable us to improve further our atmospheric transmittance models. It was further noted that the proposed SSMIS conical-scanning microwave spectrometer on the military DMSP Block 5D-3 spacecraft designed to measure stratospheric and mesospheric temperature profiles will be observing the Zeeman-split oxygen lines with sufficient spectral resolution that the changing Doppler shifts with view angle will substantially degrade the potential system performance unless remedied; this was briefly studied and documented
Silver Triflate/p-TSA Co-Catalysed Synthesis of 3-Substituted Isocoumarins from 2-Alkynylbenzoates
In this paper, we describe the silver triflate/p-toluensulfonic acid co-catalysed synthesis of seventeen isocoumarins and two thieno[2,3-c]pyran-7-ones starting from 2-alkynylbenzoates and 3-alkynylthiophene-2-carboxylates, respectively. The reactions proceed with absolute regioselectivity under mild reaction conditions and low catalyst loading, to give the desired products in good to excellent yields. A conceivable reaction mechanism is proposed and supported by isotope-exchange tests, and 1H NMR studies and ad-hoc experiments
Simple atomic quantum memory suitable for semiconductor quantum dot single photons
Quantum memories matched to single photon sources will form an important
cornerstone of future quantum network technology. We demonstrate such a memory
in warm Rb vapor with on-demand storage and retrieval, based on
electromagnetically induced transparency. With an acceptance bandwidth of
= 0.66~GHz the memory is suitable for single photons emitted by
semiconductor quantum dots. In this regime, vapor cell memories offer an
excellent compromise between storage efficiency, storage time, noise level, and
experimental complexity, and atomic collisions have negligible influence on the
optical coherences. Operation of the memory is demonstrated using attenuated
laser pulses on the single photon level. For 50 ns storage time we measure
\emph{end-to-end efficiency}
of the fiber-coupled memory, with an \emph{total intrinsic efficiency}
. Straightforward technological improvements can
boost the end-to-end-efficiency to ; beyond
that increasing the optical depth and exploiting the Zeeman substructure of the
atoms will allow such a memory to approach near unity efficiency.
In the present memory, the unconditional readout noise level of photons is dominated by atomic fluorescence, and for input pulses
containing on average photons the signal to noise level would
be unity
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