9,811 research outputs found
Integration of Local Poetic Voices: an Interview with Lawson Fusao Inada
An interview with Lawson Fusoa Inad
Control of flower development in Arabidopsis thaliana by APETALA1 and interacting genes
Mutations in the APETALA1 gene disturb two phases of flower development, flower meristem specification and floral organ specification. These effects become manifest as a partial conversion of flowers into inflorescence shoots and a disruption of sepal and petal development. We describe the changes in an allelic series of nine apetala1 mutants and show that the two functions of APETALA1 are separable. We have also studied the interaction between APETALA1 and other floral genes by examining the phenotypes of multiply mutant plants and by in situ hybridization using probes for several floral control genes. The results suggest that the products of APETALA1 and another gene, LEAFY, are required to ensure that primordia arising on the flanks of the inflorescence apex adopt a floral fate, as opposed to becoming an inflorescence shoot. APETALA1 and LEAFY have distinct as well as overlapping functions and they appear to reinforce each other's action. CAULIFLOWER is a newly discovered gene which positively regulates both APETALA1 and LEAFY expression. All functions of CAULIFLOWER are redundant with those of APETALA1. APETALA2 also has an early function in reinforcing the action of APETALA1 and LEAFY, especially if the activity of either is compromised by mutation. After the identity of a flower primordium is specified, APETALA1 interacts with APETALA2 in controlling the development of the outer two whorls of floral organs
Ligand regulation of the quaternary organization of cell surface M3 muscarinic acetylcholine receptors analyzed by fluorescence resonance energy transfer (FRET) imaging and homogenous time-resolved FRET
Flp-In T-REx 293 cells expressing a wild type human M muscarinic acetylcholine receptor construct constitutively and able to express a Receptor Activated Solely by Synthetic Ligand (RASSL) form of this receptor on demand maintained response to the muscarinic agonist carbachol but developed response to clozapine-N-oxide only upon induction of the RASSL. The two constructs co-localized at the plasma membrane and generated strong ratiometric fluorescence resonance energy transfer (FRET) signals consistent with direct physical interactions. Increasing levels of induction of the FRET-donor RASSL did not alter wild type receptor FRET-acceptor levels substantially. However, ratiometric FRET was modulated in a bell-shaped fashion with maximal levels of the donor resulting in decreased FRET. Carbachol, but not the antagonist atropine, significantly reduced the FRET signal. Cell surface homogenous time-resolved FRET, based on SNAP-tag technology and employing wild type and RASSL forms of the human M receptor expressed stably in Flp-In TREx 293 cells, also identified cell surface dimeric/oligomeric complexes. Now, however, signals were enhanced by appropriate selective agonists. At the wild type receptor large increases in FRET signal to carbachol and acetylcholine were concentration-dependent with EC values consistent with the relative affinities of the two ligands. These studies confirm the capacity of the human M muscarinic acetylcholine receptor to exist as dimeric/oligomeric complexes at the surface of cells and demonstrate that the organization of such complexes can be modified by ligand binding. However, conclusions as to the effect of ligands on such complexes may depend on the approach used
Ab Initio studies of the atomic structure and electronic density of states of pure and hydrogenated a-Si
We propose a method to simulate a-Si and a-Si:H using an ab initio approach
based on the Harris functional and thermally amorphisized periodically
continued cells with at least 64 atoms, and calculate their radial distribution
functions. Hydrogen incorporation was achieved via diffusive random addition.
The electronic density of states (DOS) is obtained using density functional
theory with the aid of both the Harris-functional and Kohn-Sham-LDA approaches.
Two time steps are used, 2.44 and 10 fs for the pure, and 0.46 and 2 fs for the
hydrogenated, to see their effect on the topological and DOS structure of the
samples. The calculated long time-step radial features of a-Si are in very good
agreement with experiment whereas for a-Si:H the short time-step partial and
total radial features agree well; for the long time-step simulation molecular
hydrogen appears during annealing.The long time-step a-Si has a well defined
gap with two dangling bonds, that clears and increases upon hydrogen addition
and relaxation, as expected. The short time-step structures have more defects,
both dangling and floating bonds, that are less characteristic of a good
sample; however the radial structures of a-Si:H are in better agreement with
experiment indicating that the experimental work was done on defective samples.Comment: 11 pages, RevTeX, 16 figures, submitted to Phys. Rev. B 16 June 200
On The Removal of Agricultural Price Bands in Chile: A General Equilibrium Analysis
Chile has supported its agriculture with the use of price bands on selected commodities namely wheat, vegetable oils and fats, and sugar. In this paper we consider agricultural reform and how urban unemployment, and rural-urban migration, may alter the expected welfare effects of agricultural reform. We utilize a new CGE model of the Chilean economy based on the Harris-Todaro ramework, incorporating imperfect labor mobility, and consider both price band removal and more extensive agricultural reform that eliminates all tariffs on agricultural and food commodities in Chile. Results show that if trade reforms damage the rural economy in Chile, potential gains in welfare from lower agricultural prices are offset by increased urban unemployment and lower rural wages resulting in net welfare loss from trade reform.
Age Determination from Biological Stains Using Messenger RNS Profiling Analysis. DIV
Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays, systems, methods and kits for the age determination of an individual from bloodstains or samples of unknown origin. The methodology is based on gene expression profiling analysis in which novel human newborn fetal specific genes are identified by detecting the presence of appropriate messenger RNA species
Spatially Extended 21 cm Signal from Strongly Clustered UV and X-Ray Sources in the Early Universe
We present our prediction for the local 21 cm differential brightness
temperature () from a set of strongly clustered sources of
Population III (Pop III) and II (Pop II) objects in the early Universe, by a
numerical simulation of their formation and radiative feedback. These objects
are located inside a highly biased environment, which is a rare, high-density
peak ("Rarepeak") extending to comoving Mpc. We study the impact of
ultraviolet (UV) and X-ray photons on the intergalactic medium (IGM) and the
resulting , when Pop III stars are assumed to emit X-ray photons
by forming X-ray binaries very efficiently. We parameterize the rest-frame
spectral energy distribution (SED) of X-ray photons, which regulates X-ray
photon-trapping, IGM-heating, secondary Lyman-alpha pumping and the resulting
morphology of . A combination of emission () and
absorption () regions appears in varying amplitudes and angular
scales. The boost of the signal by the high-density environment
() and on a relatively large scale combine to make Rarepeak a
discernible, spatially-extended () object for 21 cm observation
at , which is found to be detectable as a single object
by SKA with integration time of hours. Power spectrum analysis by
some of the SKA precursors (LOFAR, MWA, PAPER) of such rare peaks is found
difficult due to the rarity of these peaks, and the contribution only by these
rare peaks to the total power spectrum remains subdominant compared to that by
all astrophysical sources.Comment: Accepted for publication in ApJ; Major revision done on the
cosmological 21-cm line transfer, allowing for generic cases with peculiar
motion of gas and non-negligible optical dept
A four-lidar view of Cirrus from the FIRE IFO: 27-28 October 1986
The four ground-based lidar systems that participated in the 1986 FIRE IFO were configured in a diamond-shaped array across central and southern Wisconsin. Data were generally collected in the zenith pointing mode, except for the Doppler lidar, which regularly operated in a scanning mode with intermittent zenith observations. As a component of the cirrus case study of 27 and 28 October 1986 selected for initial analysis, data collected by the remote sensor ensemble from 1600 (on the 27th) to 2400 UTC (on the 28th) is described and compared. In general, the cirrus studied on the 27th consisted of intermittent layers of thin and subvisual cirrus clouds. Particularly at Wausau, subvisual cirrus was detected from 11.0 to 11.5 km MSL, just below the tropopause. At lower levels, occasional cirrus clouds between approx. 8.0 to 9.5 km were detected from all ground sites. Preliminary analysis of the four-lidar dataset reveals the passage of surprisingly consistent cloud features across the experiment area. A variety of types and amounts of middle and high level clouds occurred, ranging from subvisual cirrus to deep cloud bands. It is expected that the ground-based lidar measurements from this case study, as well as the airborne observations, will provide an excellent data base for comparison to satellite observations
Are Americans Ambivalent Towards Racial Policies?
Few debates, political or academic, are as conflictual as those over racial policy. In this paper, we explore the possibility that individual attitudes are internally conflictual through the use of inferential statistical techniques that estimate variability in individual respondents' considerations about racial policy. We consider six separate core beliefs potentially relevant towards racial policy choice (modern racism, anti-black stereotyping, authoritarianism, individualism, and anti-semitism), for four different policy choices. We evaluate two separate models for the source of individual variance: conflicting values and direct effects of values. Our analysis leads us to conclude that modern racism trumps rival explanatory variables in explanations of racial policy choice, and that variability in attitudes toward racial policy is due to uncertainty, and not to ambivalence
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