1,786 research outputs found
The inexorable resistance of inertia determines the initial regime of drop coalescence
Drop coalescence is central to diverse processes involving dispersions of
drops in industrial, engineering and scientific realms. During coalescence, two
drops first touch and then merge as the liquid neck connecting them grows from
initially microscopic scales to a size comparable to the drop diameters. The
curvature of the interface is infinite at the point where the drops first make
contact, and the flows that ensue as the two drops coalesce are intimately
coupled to this singularity in the dynamics. Conventionally, this process has
been thought to have just two dynamical regimes: a viscous and an inertial
regime with a crossover region between them. We use experiments and simulations
to reveal that a third regime, one that describes the initial dynamics of
coalescence for all drop viscosities, has been missed. An argument based on
force balance allows the construction of a new coalescence phase diagram
Can Payments-in-King Solve the Surplus Problem?
Does this approach offer a genuine opportunity both to reduce our surplus stocks and the cost of carrying them and also to adjust our farm production to improve farm prices and incomes? Let\u27s look more closely
An automated and versatile ultra-low temperature SQUID magnetometer
We present the design and construction of a SQUID-based magnetometer for
operation down to temperatures T = 10 mK, while retaining the compatibility
with the sample holders typically used in commercial SQUID magnetometers. The
system is based on a dc-SQUID coupled to a second-order gradiometer. The sample
is placed inside the plastic mixing chamber of a dilution refrigerator and is
thermalized directly by the 3He flow. The movement though the pickup coils is
obtained by lifting the whole dilution refrigerator insert. A home-developed
software provides full automation and an easy user interface.Comment: RevTex, 10 pages, 10 eps figures. High-resolution figures available
upon reques
A Look at the Conservation Reserve
Last fall, farmers voted in a new price-support program for corn with flexible price supports and unrestricted acreage. The companion program, the conservation reserve, assumes new importance and may help control acreage
Dopamine suppresses persistent network activity via D(1) -like dopamine receptors in rat medial entorhinal cortex.
PublishedJournal ArticleResearch Support, N.I.H., IntramuralResearch Support, Non-U.S. Gov'tThis is the final version of the article. Available from Wiley via the DOI in this record.Cortical networks display persistent activity in the form of periods of sustained synchronous depolarizations ('UP states') punctuated by periods of relative hyperpolarization ('DOWN states'), which together form the slow oscillation. UP states are known to be synaptically generated and are sustained by a dynamic balance of excitation and inhibition, with fast ionotropic glutamatergic excitatory and GABAergic inhibitory conductances increasing during the UP state. Previously, work from our group demonstrated that slow metabotropic GABA receptors also play an important role in terminating the UP state, but the effects of other neuromodulators on this network phenomenon have received little attention. Given that persistent activity is a neural correlate of working memory and that signalling through dopamine receptors has been shown to be critical for working memory tasks, we examined whether dopaminergic neurotransmission affected the slow oscillation. Here, using an in vitro model of the slow oscillation in rat medial entorhinal cortex, we showed that dopamine strongly and reversibly suppressed cortical UP states. We showed that this effect was mediated through D1 -like and not D2 -like dopamine receptors, and we found no evidence that tonic dopaminergic transmission affected UP states in our model.This work was supported by the Wellcome Trust OXION initiative (M.T.C. and O.P.) and a National Institute of Child Health and Human Development (NICHD) intramural award (C.J.M.). M.T.C. held a Wellcome Trust Prize Studentship. E.W.M. is supported by the NIH MD/PhD Partnership Training programme and by the Rhodes Trust
Distinct mechanisms of Up state maintenance in the medial entorhinal cortex and neocortex
The medial entorhinal cortex (mEC) is a key structure which controls the communication between the hippocampus and the neocortex. During slow-wave sleep, it stands out from other cortical regions by exhibiting persistent activity that outlasts neocortical Up states, decoupling the entorhinal cortex-hippocampal interaction from the neocortex. Here, we compared the mechanisms involved in the maintenance of the Up state in the barrel cortex (BC) and mEC using whole cell recordings in acute mouse brain slices. Bath application of an NMDA receptor antagonist abolished Up states in the BC, and reduced the incidence but not the duration of Up states in the mEC. Conversely, blockade of kainate receptors decreased Up state duration in the mEC, but not in the BC. Voltage clamp recordings demonstrated the presence of a non-NMDA glutamate receptor-mediated slow excitatory postsynaptic current, sensitive to the selective kainate receptor antagonist UBP-302, in layer III neurons of the mEC, which was not observed in the BC. Moreover, we found that kainate receptor-mediated currents assist in recovery back to the Up state membrane potential following a current-induced hyperpolarisation of individual cells in the mEC. Finally, we were able to generate Up state activity in a network model of exponential integrate-and-fire neurons only supported by AMPA and kainate receptor-mediated currents. We propose that synaptic kainate receptors are responsible for the unique properties of mEC Up states.We also would like to acknowledge support from the Medical Research Council, UK. R.J.D. is on the Cambridge MB/PhD programme. D.S.B. is supported by the Gates Cambridge Trust. V.M. was supported by a Swiss National Science Foundation Early Postdoc Mobility Fellowship
Output Management for Agriculture?
Could agriculture learn to manage its output from some other industries? Some industries have experience in managing excess capacity. Agriculture might want to look at the alternative methods and their consequences
Pressure-induced changes of the vibrational modes of spin-crossover complexes studied by nuclear resonance scattering of synchrotron radiation
Nuclear inelastic scattering (NIS) spectra were recorded for the
spin-crossover complexes STP and ETP (STP =
[Fe(1,1,1-trisf[N-(2-pyridylmethyl)-N-methylamino]methylg- ethane)](ClO4)2 and
ETP =
[Fe(1,1,1-trisf[N-(2-pyridylmethyl)-N-methylamino]methylg-butane)](ClO4)2) at
30 K and at room temperature and also at ambient pressure and applied pressure
(up to 2.6 GPa). Spin transition from the high-spin (HS) to the low-spin (LS)
state was observed by lowering temperature and also by applying pressure at
room temperature and has been assigned to the hardening of iron-bond stretching
modes due to the smaller volume in the LS isomer
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