Taste receptor cells use multiple signaling pathways to detect chemicals in potential food items. These cells are functionally grouped into different types: Type I cells act as support cells and have ...glial-like properties; Type II cells detect bitter, sweet, and umami taste stimuli; and Type III cells detect sour and salty stimuli. We have identified a new population of taste cells that are broadly tuned to multiple taste stimuli including bitter, sweet, sour, and umami. The goal of this study was to characterize these broadly responsive (BR) taste cells. We used an IP.sub.3 R3-KO mouse (does not release calcium (Ca.sup.2+) from internal stores in Type II cells when stimulated with bitter, sweet, or umami stimuli) to characterize the BR cells without any potentially confounding input from Type II cells. Using live cell Ca.sup.2+ imaging in isolated taste cells from the IP.sub.3 R3-KO mouse, we found that BR cells are a subset of Type III cells that respond to sour stimuli but also use a PLCbeta signaling pathway to respond to bitter, sweet, and umami stimuli. Unlike Type II cells, individual BR cells are broadly tuned and respond to multiple stimuli across different taste modalities. Live cell imaging in a PLCbeta3-KO mouse confirmed that BR cells use this signaling pathway to respond to bitter, sweet, and umami stimuli. Short term behavioral assays revealed that BR cells make significant contributions to taste driven behaviors and found that loss of either PLCbeta3 in BR cells or IP.sub.3 R3 in Type II cells caused similar behavioral deficits to bitter, sweet, and umami stimuli. Analysis of c-Fos activity in the nucleus of the solitary tract (NTS) also demonstrated that functional Type II and BR cells are required for normal stimulus induced expression.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present a fully relativistic energy-conserving binary collision model for particle simulations with large density scale plasmas. Our model deals with collisions between weighted particles of ...arbitrary species, conserving energy perfectly in each collision while momentum is conserved on the average. We also discuss a new method to model extremely high densities, applicable to a wide range of plasmas from the cold, non-relativistic to the ultra-relativistic regime in the high energy density physics.
Earth's Continental Lithosphere Through Time Hawkesworth, Chris J; Cawood, Peter A; Dhuime, Bruno ...
Annual review of earth and planetary sciences,
01/2017, Letnik:
45, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The record of the continental lithosphere is patchy and incomplete; no known rock is older than 4.02 Ga, and less than 5% of the rocks preserved are older than 3 Ga. In addition, there is no ...recognizable mantle lithosphere from before 3 Ga. We infer that there was lithosphere before 3 Ga and that ∼3 Ga marks the stabilization of blocks of continental lithosphere that have since survived. This was linked to plate tectonics emerging as the dominant tectonic regime in response to thermal cooling, the development of a more rigid lithosphere, and the recycling of water, which may in turn have facilitated plate tectonics. A number of models, using different approaches, suggest that at 3 Ga the volume of continental crust was ∼70% of its present-day volume and that this may be a minimum value. The continental crust before 3 Ga was on average more mafic than that generated subsequently, and this pre-3 Ga mafic new crust had fractionated Lu Hf and Sm Nd ratios as inferred for the sources of tonalite-trondhjemite-granodiorite and later granites. The more intermediate composition of new crust generated since 3 Ga is indicated by its higher Rb Sr ratios. This change in composition was associated with an increase in crustal thickness, which resulted in more emergent crust available for weathering and erosion. This in turn led to an increase in the Sr isotope ratios of seawater and in the drawdown of CO
2
. Since 3 Ga, the preserved record of the continental crust is marked
by global cycles of peaks and troughs of U-Pb crystallization ages, with the peaks of ages appearing to match periods of supercontinent assembly. There is increasing evidence that the peaks of ages represent enhanced preservation of magmatic rocks in periods leading up to and including continental collision in the assembly of supercontinents. These are times of increased crustal growth because more of the crust that is generated is retained within the crust. The rates of generation of continental crust and mantle lithosphere may have remained relatively constant at least since 3 Ga, yet the rates of destruction of continental crust have changed with time. Only relatively small volumes of rock are preserved from before 3 Ga, and so it remains difficult to establish which of these are representative of global processes and the extent to which the rock record before 3 Ga is distorted by particular biases.
In this paper we examine the innovation effects of environmental policy instruments in four literatures: theoretical models on incentives for eco-innovation, econometric studies based on observed ...data, survey analysis based on stated information and technology case studies. The aim of this paper is to critically examine the methods and the results. We argue that the case studies literature, even when its results are specific and difficult to generalise, is a necessary source of empirical evidence about policy impacts and the factors responsible for these impacts, pointing to issues that are neglected in the theoretical and econometric literature such as the specifics of the innovation context and policy interaction effects. The paper states five synthesised findings and makes a plea for multi-method analysis. One other important synthesised finding is that the influence of market-based instruments on innovation (such as emission trading and taxes) is far weaker than assumed.
Photo-ID is widely used in security settings, despite research showing that viewers find it very difficult to match unfamiliar faces. Here we test participants with specialist experience and training ...in the task: passport-issuing officers. First, we ask officers to compare photos to live ID-card bearers, and observe high error rates, including 14% false acceptance of 'fraudulent' photos. Second, we compare passport officers with a set of student participants, and find equally poor levels of accuracy in both groups. Finally, we observe that passport officers show no performance advantage over the general population on a standardised face-matching task. Across all tasks, we observe very large individual differences: while average performance of passport staff was poor, some officers performed very accurately--though this was not related to length of experience or training. We propose that improvements in security could be made by emphasising personnel selection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
We discuss a generalized dominance ordering for irreducible representations of the symmetric group
S
n
with the aim of distinguishing the corresponding states in the 1/2-BPS sector of U(
N
...) Super Yang-Mills theory when a certain finite number of Casimir operators are known. Having knowledge of a restricted set of Casimir operators was proposed as a mechanism for information loss in this sector and its dual gravity theory in AdS
5
×
S
5
. It is well-known that the states in this sector are labeled by Young diagrams with
n
boxes. We propose a generalization of the well-known dominance ordering of Young diagrams. Using this generalization, we posit a conjecture to determine an upper bound for the number of Casimir operators needed to distinguish between the 1/2-BPS states and thus also between their duals in the gravity theory. We offer numerical and analytic evidence for the conjecture. Lastly, we discuss implications of this conjecture when the energy
n
of the states is asymptotically large.
Zircon has played a critically important role in our understanding of the growth and evolution of the Earth. The U–Pb isotope system as preserved in zircon, more than any other mineral or method, has ...provided the most precise geochronological constraints for timing of geological events and processes on the Earth. More recently, technological advances have allowed for the precise determination of the Hf isotope composition of zircon, a geochemical tracer that has provided important details on the Earth's chemical evolution, in particular the evolution of the crust–mantle system. When combined, U–Pb ages and Hf isotopes in zircons hold the promise of providing unprecedented resolution in the timing and processes of planetary differentiation. Nowhere is this more true than for the early history of the Earth, where younger tectonothermal processes have compromised the isotope information in bulk rock samples. With the promise of this integrated technique, however, lies numerous potential pitfalls in the acquisition and interpretation of these data. In this paper we review several important issues related to unraveling the complexities of integrated U–Pb age and Hf isotope datasets, especially with respect to understanding crust–mantle evolution. In particular, we address the potential difficulty of assigning accurate initial Hf isotope compositions as well as some of the inherent problems associated with so-called “depleted-mantle model ages”. Finally, we make some suggestions regarding the optimum analytical approach and presentation of the Hf (and Nd) isotope data to obtain the clearest record of Earth's chemical evolution.
•We review several issues related to complexities in integrated U-Pb age and Hf isotope datasets, especially related to the record of crust-mantle evolution.•We address the potential difficulty of determining accurate initial Hf isotope compositions and epsilon Hf values.•We identify the inherent problems associated with “depleted-mantle model ages”.•We suggest the best analytical approach to, and presentation of, Hf (and Nd) isotope data to obtain the clearest record of Earth’s chemical evolution.
Granitic plutonism is the principal agent of crustal differentiation, but linking granite emplacement to crust formation requires knowledge of the magmatic evolution, which is notoriously difficult ...to reconstruct from bulk rock compositions. We unlocked the plutonic archive through hafnium (Hf) and oxygen (O) isotope analysis of zoned zircon crystals from the classic hornblende-bearing (I-type) granites of eastern Australia. This granite type forms by the reworking of sedimentary materials by mantle-like magmas instead of by remelting ancient metamorphosed igneous rocks as widely believed. I-type magmatism thus drives the coupled growth and differentiation of continental crust.
With candor and humor, a journalist offers an intimate portrait of faceblindness
With candor and humor, a journalist offers an intimate portrait of faceblindness
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