2,284 research outputs found
Floating PVs in Terms of Power Generation, Environmental Aspects, Market Potential, and Challenges
This is the final version. Available on open access from MDPI via the DOI in this recordLimited reserves of fossil fuels, rising environmental concerns, and a remarkable increase in electricity demand have led to the necessity of harnessing solar energy on a large scale. For this purpose, there has been a noticeable stimulation into photovoltaic power plants (PVPPs) over the last three decades, but the land requirement for PVPPs is still a handicap in many countries since valuable lands are considered for other purposes such as agriculture and livestock. For effective conservation of valuable lands and water resources, PVPPs are preferred to be installed on various water bodies such as oceans, seas, lagoons, lakes, rivers, dams, canals, wastewater treatment plants, irrigation ponds, fish farms, wineries, reservoirs, etc. PV systems on water bodies are called floating PVPPs, and they have outstanding advantages compared with land-based PVPPs including better energy generation owing to passive cooling effects, higher system efficiency and reliability, and lower dirt and dust accumulation on PV modules thus lower operating costs. There are also some significant environmental features provided by floating PVs. Shading effects due to PV coverage reduce water losses arising from evaporation. Moreover, algae growth is limited because of mitigated solar radiation, which yields better water quality. This review presents more insight on floating PVPPs in terms of several aspects such as electricity generation, system efficiency, reliability and sustainability, experimental applications and facilities in operation, water and carbon saving as well as challenges
Knockdown of MBP-1 in Human Foreskin Fibroblasts Induces p53-p21 Dependent Senescence
MBP-1 acts as a general transcriptional repressor. Overexpression of MBP-1 induces cell death in a number of cancer cells and regresses tumor growth. However, the function of endogenous MBP-1 in normal cell growth regulation remains unknown. To unravel the role of endogenous MBP-1, we knocked down MBP-1 expression in primary human foreskin fibroblasts (HFF) by RNA interference. Knockdown of MBP-1 in HFF (HFF-MBPsi-4) resulted in an induction of premature senescence, displayed flattened cell morphology, and increased senescence-associated beta-galactosidase activity. FACS analysis of HFF-MBPsi-4 revealed accumulation of a high number of cells in the G1-phase. A significant upregulation of cyclin D1 and reduction of cyclin A was detected in HFF-MBPsi-4 as compared to control HFF. Senescent fibroblasts exhibited enhanced expression of phosphorylated and acetylated p53, and cyclin-dependent kinase inhibitor, p21. Further analysis suggested that promyolocytic leukemia protein (PML) bodies are dramatically increased in HFF-MBPsi-4. Together, these results demonstrated that knockdown of endogenous MBP-1 is involved in cellular senescence of HFF through p53-p21 pathway
Phosphorylation of the androgen receptor is associated with reduced survival in hormonerefractory prostate cancer patients
Cell line studies demonstrate that the PI3K/Akt pathway is upregulated in hormone-refractory prostate cancer (HRPC) and can result in phosphorylation of the androgen receptor (AR). The current study therefore aims to establish if this has relevance to the development of clinical HRPC. Immunohistochemistry was employed to investigate the expression and phosphorylation status of Akt and AR in matched hormone-sensitive and -refractory prostate cancer tumours from 68 patients. In the hormone-refractory tissue, only phosphorylated AR (pAR) was associated with shorter time to death from relapse (<i>P</i>=0.003). However, when an increase in expression in the transition from hormone-sensitive to -refractory prostate cancer was investigated, an increase in expression of PI3K was associated with decreased time to biochemical relapse (<i>P</i>=0.014), and an increase in expression of pAkt<sup>473</sup> and pAR<sup>210</sup> were associated with decreased disease-specific survival (<i>P</i>=0.0019 and 0.0015, respectively). Protein expression of pAkt<sup>473</sup> and pAR<sup>210</sup> also strongly correlated (<i>P</i><0.001, c.c.=0.711) in the hormone-refractory prostate tumours. These results provide evidence using clinical specimens, that upregulation of the PI3K/Akt pathway is associated with phosphorylation of the AR during development of HRPC, suggesting that this pathway could be a potential therapeutic target
Quasi-normal frequencies: Key analytic results
The study of exact quasi-normal modes [QNMs], and their associated
quasi-normal frequencies [QNFs], has had a long and convoluted history -
replete with many rediscoveries of previously known results. In this article we
shall collect and survey a number of known analytic results, and develop
several new analytic results - specifically we shall provide several new QNF
results and estimates, in a form amenable for comparison with the extant
literature. Apart from their intrinsic interest, these exact and approximate
results serve as a backdrop and a consistency check on ongoing efforts to find
general model-independent estimates for QNFs, and general model-independent
bounds on transmission probabilities. Our calculations also provide yet another
physics application of the Lambert W function. These ideas have relevance to
fields as diverse as black hole physics, (where they are related to the damped
oscillations of astrophysical black holes, to greybody factors for the Hawking
radiation, and to more speculative state-counting models for the Bekenstein
entropy), to quantum field theory (where they are related to Casimir energies
in unbounded systems), through to condensed matter physics, (where one may
literally be interested in an electron tunelling through a physical barrier).Comment: V1: 29 pages; V2: Reformatted, 31 pages. Title changed to reflect
major additions and revisions. Now describes exact QNFs for the double-delta
potential in terms of the Lambert W function. V3: Minor edits for clarity.
Four references added. No physics changes. Still 31 page
Semi-analytic results for quasi-normal frequencies
The last decade has seen considerable interest in the quasi-normal
frequencies [QNFs] of black holes (and even wormholes), both asymptotically
flat and with cosmological horizons. There is wide agreement that the QNFs are
often of the form omega_n = (offset) + i n (gap), though some authors have
encountered situations where this behaviour seems to fail. To get a better
understanding of the general situation we consider a semi-analytic model based
on a piecewise Eckart (Poeschl-Teller) potential, allowing for different
heights and different rates of exponential falloff in the two asymptotic
directions. This model is sufficiently general to capture and display key
features of the black hole QNFs while simultaneously being analytically
tractable, at least for asymptotically large imaginary parts of the QNFs. We
shall derive an appropriate "quantization condition" for the asymptotic QNFs,
and extract as much analytic information as possible. In particular, we shall
explicitly verify that the (offset)+ i n (gap) behaviour is common but not
universal, with this behaviour failing unless the ratio of rates of exponential
falloff on the two sides of the potential is a rational number. (This is
"common but not universal" in the sense that the rational numbers are dense in
the reals.) We argue that this behaviour is likely to persist for black holes
with cosmological horizons.Comment: V1: 28 pages, no figures. V2: 3 references added, no physics changes.
V3: 29 pages, 9 references added, no physics changes; V4: reformatted, now 27
pages. Some clarifications, comparison with results obtained by monodromy
techniques. This version accepted for publication in JHEP. V5: Minor typos
fixed. Compatible with published versio
Dynamic modeling of mean-reverting spreads for statistical arbitrage
Statistical arbitrage strategies, such as pairs trading and its
generalizations, rely on the construction of mean-reverting spreads enjoying a
certain degree of predictability. Gaussian linear state-space processes have
recently been proposed as a model for such spreads under the assumption that
the observed process is a noisy realization of some hidden states. Real-time
estimation of the unobserved spread process can reveal temporary market
inefficiencies which can then be exploited to generate excess returns. Building
on previous work, we embrace the state-space framework for modeling spread
processes and extend this methodology along three different directions. First,
we introduce time-dependency in the model parameters, which allows for quick
adaptation to changes in the data generating process. Second, we provide an
on-line estimation algorithm that can be constantly run in real-time. Being
computationally fast, the algorithm is particularly suitable for building
aggressive trading strategies based on high-frequency data and may be used as a
monitoring device for mean-reversion. Finally, our framework naturally provides
informative uncertainty measures of all the estimated parameters. Experimental
results based on Monte Carlo simulations and historical equity data are
discussed, including a co-integration relationship involving two
exchange-traded funds.Comment: 34 pages, 6 figures. Submitte
Common Variants in CRP and LEPR Influence High Sensitivity C-Reactive Protein Levels in North Indians
BACKGROUND: High sensitivity C-reactive protein (hsCRP) levels are shown to be influenced by genetic variants in Europeans; however, little is explored in Indian population. METHODS: Herein, we comprehensively evaluated association of all previously reported genetic determinants of hsCRP levels, including 18 cis (proximal to CRP gene) and 73 trans-acting (distal to CRP gene) variants in 4,200 North Indians of Indo-European ethnicity. First, we evaluated association of 91 variants from 12 candidate loci with hsCRP levels in 2,115 North Indians (1,042 non-diabetic subjects and 1,073 patients with type 2 diabetes). Then, cis and trans-acting variants contributing maximally to hsCRP level variation were further replicated in an independent 2,085 North Indians (1,047 patients with type 2 diabetes and 1,038 non-diabetic subjects). RESULTS: We found association of 12 variants from CRP, LEPR, IL1A, IL6, and IL6R with hsCRP levels in non-diabetic subjects. However, only rs3093059-CRP [ÎČâ=â0.33, Pâ=â9.6Ă10â»â”] and the haplotype harboring rs3093059 risk allele [ÎČâ=â0.32 ”g/mL, Pâ=â1.4Ă10â»âŽ/P(perm)â=â9.0Ă10â»âŽ] retained significance after correcting for multiple testing. The cis-acting variant rs3093059-CRP had maximum contribution to the variance in hsCRP levels (1.14%). Among, trans-acting variants, rs1892534-LEPR was observed to contribute maximally to hsCRP level variance (0.59%). Associations of rs3093059-CRP and rs1892534-LEPR were confirmed by replication and attained higher significance after meta-analysis [ÎČ(meta)â=â0.26/0.22; P(meta)â=â4.3Ă10â»â·/7.4Ă10â»Âł and ÎČ(meta)â=â-0.15/-0.12; P(meta)â=â2.0Ă10â»â¶/1.6Ă10â»â¶ for rs3093059 and rs1892534, respectively in non-diabetic subjects and all subjects taken together]. CONCLUSION: In conclusion, we identified rs3093059 in CRP and rs1892534 in LEPR as major cis and trans-acting contributor respectively, to the variance in hsCRP levels in North Indian population
Epiploic appendagitis â clinical characteristics of an uncommon surgical diagnosis
<p>Abstract</p> <p>Background</p> <p>Epiploic appendagitis (EA) is a rare cause of focal abdominal pain in otherwise healthy patients with mild or absent secondary signs of abdominal pathology. It can mimick diverticulitis or appendicitis on clinical exam. The diagnosis of EA is very infrequent, due in part to low or absent awareness among general surgeons. The objective of this work was to review the authors' experience and describe the clinical presentation of EA.</p> <p>Methods</p> <p>All patients diagnosed with EA between January 2004 and December 2006 at an urban surgical emergency room were retrospectively reviewed by two authors in order to share the authors' experience with this rare diagnosis. The operations were performed by two surgeons. Pathological examinations of specimens were performed by a single pathologist. A review of clinical presentation is additionally undertaken.</p> <p>Results</p> <p>Ten patients (3 females and 7 males, average age: 44.6 years, range: 27â76 years) were diagnosed with symptomatic EA. Abdominal pain was the leading symptom, the pain being localized in the left (8 patients, 80 %) and right (2 patients, 20%) lower quadrant. All patients were afebrile, and with the exception of one patient, nausea, vomiting, and diarrhea were not present. CRP was slightly increased (mean: 1.2 mg/DL) in three patients (33%). Computed tomography findings specific for EA were present in five patients. Treatment was laparoscopic excision (n = 8), excision via conventional laparotomy (n = 1) and conservative therapy (n = 1).</p> <p>Conclusion</p> <p>In patients with localized, sharp, acute abdominal pain not associated with other symptoms such as nausea, vomiting, fever or atypical laboratory values, the diagnosis of EA should be considered. Although infrequent up to date, with the increase of primary abdominal CT scans and ultrasound EA may well be diagnosed more frequently in the future.</p
Holographic phase diagram of quark-gluon plasma formed in heavy-ions collisions
The phase diagram of quark gluon plasma (QGP) formed at a very early stage
just after the heavy ion collision is obtained by using a holographic dual
model for the heavy ion collision. In this dual model colliding ions are
described by the charged shock gravitational waves. Points on the phase diagram
correspond to the QGP or hadronic matter with given temperatures and chemical
potentials. The phase of QGP in dual terms is related to the case when the
collision of shock waves leads to formation of trapped surface. Hadronic matter
and other confined states correspond to the absence of trapped surface after
collision.
Multiplicity of the ion collision process is estimated in the dual language
as area of the trapped surface. We show that a non-zero chemical potential
reduces the multiplicity. To plot the phase diagram we use two different dual
models of colliding ions, the point and the wall shock waves, and find
qualitative agreement of the results.Comment: 33 pages, 14 figures, typos correcte
Enhancing effectiveness of capillary electrophoresis as an analytical tool in the supramolecular acidity modification
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