637 research outputs found
GAME THEORY ANALYSIS OF COMPETITION FOR GROUNDWATER INVOLVING EL PASO, TEXAS AND CIUDAD JUAREZ, MEXICO
We examine the potential gains from cooperation in the withdrawal of water from the Hueco Bolson aquifer that provides municipal water supply for El Paso, Texas and Ciudad Juarez, Mexico. The aquifer lies beneath the international border, and both cities operate independently regarding pumping rates and withdrawals. We estimate the gains by comparing four scenarios in a dynamic setting: 1) a status quo scenario in which both cities continue extracting groundwater as they are at present, 2) a Nash non-cooperative game scenario, 3) a Nash bargaining scenario, and 4) a scenario that involves maximizing the sum of net benefits in both cities. All scenarios, including the non-cooperative game, provide a longer useful life of the Hueco Bolson aquifer than does the status quo. In the Nash bargaining scenario, both cities gain from cooperation and the sum of net benefits approaches the maximum that can be obtained by maximizing that value explicitly.Resource /Energy Economics and Policy,
ESTIMATING POTENTIAL GAINS TO COOPERATION FOR LIMITED WATER RESOURCES ALONG THE RIO GRANDE
We examine the potential gains from cooperation in the withdrawal of water from the Hueco Bolson aquifer that provides a substantial portion of municipal water supplies in El Paso, Texas and Ciudad Juarez, Mexico. The aquifer lies beneath the international border, and both cities operate independently regarding pumping rates and annual withdrawals. The natural the rate of recharge has been less than the sum of annual withdrawals since the early 1900s, and the resource likely will be depleted if current pumping rates are maintained. Optimal pumping rates and depths are described using a model that maximizes the sum of net benefits obtained from municipal water supplies in both cities. Those results are compared with pumping rates and depths obtained using a dynamic game-theory model of strategic behavior involving the two cities.Resource /Energy Economics and Policy,
Examining the assembly pathways and active microtubule mechanics underlying spindle self-organization
The bipolar organization of the microtubule-based mitotic spindle is
essential for the faithful segregation of chromosomes in cell division. Despite
our extensive knowledge of genes and proteins, the physical mechanism of how
the ensemble of microtubules can assemble into a proper bipolar shape remains
elusive. Here, we study the pathways of spindle self-organization using
cell-free Xenopus egg extracts and computer-based automated shape analysis. Our
microscopy assay allows us to simultaneously record the growth of hundreds of
spindles in the bulk cytoplasm and systematically analyze the shape of each
structure over the course of self-organization. We find that spindles that are
maturing into a bipolar shape take a route that is distinct from those ending
up with faulty structures, such as those of a tripolar shape. Moreover, matured
structures are highly stable with little occasions of transformation between
different shape phenotypes. Visualizing the movement of microtubules further
reveals a fraction of microtubules that assemble between extra poles and push
the poles apart, suggesting the presence of active extensile force that
prevents pole coalescence. Together, we propose that a proper control over the
magnitude and location of the extensile, pole-pushing force is crucial for
establishing spindle bipolarity while preventing multipolarity.Comment: 22 pages, 5 + 2 figure
Neutralisation and the perception of close-mid and open-mid vowels: the gradient between phonological categories
A prototype theoretical framework was the basis of a
study on the impact of neutralisation on the
perception of Portuguese close-mid and open-mid
vowels and the gradient between phonological
categories.
Fifteen Portuguese listeners from Lisbon
participated in identification and goodness rating
tasks of 20 random repetitions of 31 stimuli from a
/i/-/e/-/ε/-/a/ continuum. Boundaries between
categories were explored using logistic regression
curves and analysis of variance.
Results from the identification task revealed four
vowel categories marked by three statistically distinct
boundaries. The prototype of a category, i.e., the
stimulus with the highest goodness rating score, was
approximately in the centroid and the goodness score
decreased as the stimulus moved away from this
centroid. The boundary between /e/ and /ε/, the
underlying opposition that neutralises at surface level,
was less steep than between /ε/ and /a/, the opposition
that never neutralises, a possible influence of the
phonological system on speech perception
Arginine methyltransferase CARM1/PRMT4 regulates endochondral ossification
<p>Abstract</p> <p>Background</p> <p>Chondrogenesis and subsequent endochondral ossification are processes tightly regulated by the transcription factor Sox9 (SRY-related high mobility group-Box gene 9), but molecular mechanisms underlying this activity remain unclear. Here we report that coactivator-associated arginine methyltransferase 1 (CARM1) regulates chondrocyte proliferation via arginine methylation of Sox9.</p> <p>Results</p> <p>CARM1-null mice display delayed endochondral ossification and decreased chondrocyte proliferation. Conversely, cartilage development of CARM1 transgenic mice was accelerated. CARM1 specifically methylates Sox9 at its HMG domain <it>in vivo </it>and <it>in vitro</it>. Arg-methylation of Sox9 by CARM1 disrupts interaction of Sox9 with beta-catenin, regulating <it>Cyclin D1 </it>expression and cell cycle progression of chondrocytes.</p> <p>Conclusion</p> <p>These results establish a role for CARM1 as an important regulator of chondrocyte proliferation during embryogenesis.</p
Morse theory of the moment map for representations of quivers
The results of this paper concern the Morse theory of the norm-square of the
moment map on the space of representations of a quiver. We show that the
gradient flow of this function converges, and that the Morse stratification
induced by the gradient flow co-incides with the Harder-Narasimhan
stratification from algebraic geometry. Moreover, the limit of the gradient
flow is isomorphic to the graded object of the
Harder-Narasimhan-Jordan-H\"older filtration associated to the initial
conditions for the flow. With a view towards applications to Nakajima quiver
varieties we construct explicit local co-ordinates around the Morse strata and
(under a technical hypothesis on the stability parameter) describe the negative
normal space to the critical sets. Finally, we observe that the usual Kirwan
surjectivity theorems in rational cohomology and integral K-theory carry over
to this non-compact setting, and that these theorems generalize to certain
equivariant contexts.Comment: 48 pages, small revisions from previous version based on referee's
comments. To appear in Geometriae Dedicat
Title page Involvement of Human Organic Cation Transporter 1 (OCT1) in the Hepatic Uptake of YM155 Monobromide, 1-(2-Methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)- 4,9-dihydro-1H-naphtho[2,3-d]imidazolium Bromide, a Novel, Small Molecule Survivi
Abstract YM155 monobromide, 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium bromide, which is a hydrophilic and cationic compound, exhibits anti-tumor activity in experimental human hormone refractory prostate carcinoma models. Urinary excretion was 18.3% to 28.6% of the dose in the clinical phase I study, and non-renal elimination may be explained by the biliary excretion of YM155 in its unchanged form. As the penetration through the sinusoidal membrane of the hepatocytes is the first step and an important part of biliary excretion, we evaluated the uptake o
Point-of-care ultrasound utilized for foreign body in a toe: A case report of botfly larvae.
BACKGROUND: Myiasis, as defined by the Centers for Disease Control and Prevention, is infection with fly larvae commonly occurring in tropical and subtropical areas. Whereas the presentation of skin infection with organisms such as Dermatobia hominis (human botfly) is more easily recognized in these regions, identification of myiasis in the United States is difficult due to its rarity. Due to unspecific signs and symptoms, myiasis may initially be mistaken for other conditions, like cellulitis.
CASE REPORT: This case details a patient with pain, swelling, drainage, and erythema of the right second toe. The patient recently returned from Belize and reported an insect bite to the area approximately 1 month prior. She had been seen by health care professionals twice prior to presenting to our Emergency Department (ED) due to increasing pain. At those visits, the patient was prescribed antibiotics, failing to improve her symptoms. In the ED, point-of-care ultrasound (POCUS) of the soft tissue was performed and showed evidence of a foreign body consistent with cutaneous myiasis. Given the patient\u27s history of travel to Belize and known insect bite, it is prudent to have an increased suspicion for cutaneous myiasis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: To prevent a delay in diagnosis and unnecessary antibiotics, clinicians should have a high level of suspicion for botfly if a patient reports recent travel in an endemic region and pain disproportionate to an insect bite. POCUS contributes to a more efficient recognition of the disease
First-principles study of electron transport through cages
Electron transport properties of C molecules suspended between gold
electrodes are investigated using first-principles calculations. Our study
reveals that the conductances are quite sensitive to the number of C
molecules between electrodes: the conductances of C monomers are near 1
G, while those of dimers are markedly smaller, since incident electrons
easily pass the C molecules and are predominantly scattered at the
C-C junctions. Moreover, we find both channel currents locally
circulating the outermost carbon atoms.Comment: 8 pages and 3 figure
Energy landscape and dynamics of brain activity during human bistable perception.
Individual differences in the structure of parietal and prefrontal cortex predict the stability of bistable visual perception. However, the mechanisms linking such individual differences in brain structures to behaviour remain elusive. Here we demonstrate a systematic relationship between the dynamics of brain activity, cortical structure and behaviour underpinning bistable perception. Using fMRI in humans, we find that the activity dynamics during bistable perception are well described as fluctuating between three spatially distributed energy minimums: visual-area-dominant, frontal-area-dominant and intermediate states. Transitions between these energy minimums predicted behaviour, with participants whose brain activity tend to reflect the visual-area-dominant state exhibiting more stable perception and those whose activity transits to frontal-area-dominant states reporting more frequent perceptual switches. Critically, these brain activity dynamics are correlated with individual differences in grey matter volume of the corresponding brain areas. Thus, individual differences in the large-scale dynamics of brain activity link focal brain structure with bistable perception
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