2,347 research outputs found
Resource Requirements for Fault-Tolerant Quantum Simulation: The Transverse Ising Model Ground State
We estimate the resource requirements, the total number of physical qubits
and computational time, required to compute the ground state energy of a 1-D
quantum Transverse Ising Model (TIM) of N spin-1/2 particles, as a function of
the system size and the numerical precision. This estimate is based on
analyzing the impact of fault-tolerant quantum error correction in the context
of the Quantum Logic Array (QLA) architecture. Our results show that due to the
exponential scaling of the computational time with the desired precision of the
energy, significant amount of error correciton is required to implement the TIM
problem. Comparison of our results to the resource requirements for a
fault-tolerant implementation of Shor's quantum factoring algorithm reveals
that the required logical qubit reliability is similar for both the TIM problem
and the factoring problem.Comment: 19 pages, 8 figure
Transient absorption and reshaping of ultrafast XUV light by laser-dressed helium
We present a theoretical study of transient absorption and reshaping of
extreme ultraviolet (XUV) pulses by helium atoms dressed with a moderately
strong infrared (IR) laser field. We formulate the atomic response using both
the frequency-dependent absorption cross section and a time-frequency approach
based on the time-dependent dipole induced by the light fields. The latter
approach can be used in cases when an ultrafast dressing pulse induces
transient effects, and/or when the atom exchanges energy with multiple
frequency components of the XUV field. We first characterize the dressed atom
response by calculating the frequency-dependent absorption cross section for
XUV energies between 20 and 24 eV for several dressing wavelengths between 400
and 2000 nm and intensities up to 10^12 W/cm^2. We find that for dressing
wavelengths near 1600 nm, there is an Autler-Townes splitting of the 1s ---> 2p
transition that can potentially lead to transparency for absorption of XUV
light tuned to this transition. We study the effect of this XUV transparency in
a macroscopic helium gas by incorporating the time-frequency approach into a
solution of the coupled Maxwell-Schr\"odinger equations. We find rich temporal
reshaping dynamics when a 61 fs XUV pulse resonant with the 1s ---> 2p
transition propagates through a helium gas dressed by an 11 fs, 1600 nm laser
pulse.Comment: 13 pages, 8 figures, 1 table, RevTeX4, revise
Implications of Concepts of Consciousness for Understanding Pain Behaviour and the Definitiion of Pain
Judgements of the nature and severity of pain others may be experiencing are heavily influenced by an observer's preconceptions about the nature of the experience. Our personal sense of conscious experience dictates a search for consciousness characterized by the state of awareness found in competent adults, including constructive memories and thoughts, images and feelings. People incapable of verbally articulating experiences akin to those reported by competent older children and adults are at risk of having other evidence of pain denied, minimized or ignored. Despite substantial behavioural evidence for pain in the neonate and infant, and findings indicating destructive immediate and long term consequences if pain is not controlled, pain in infants and children often continues to be discounted. An alternative perspective on infant consciousness of pain focusing upon sensory and emotional components is presented. The current prominent definition of pain supports the prejudice favouring adult conceptions of consciousness by emphasizing the importance of self-report in assessing pain. Explanatory notes accompanying this definition also perpetrate the misguided belief that the experience of pain emerges as a product of early life experiences. The case for using nonverbal as well as verbal expression in the process of inferring states of pain is presented. As well, the proposition is supported that there should be explicit recognition that the experience of pain is an inherent quality of life present in all viable newborns, with the nature of the experience and its expression changing in the course of maturation and as a result of exposure to life experiences related to tissue injury
Investigation of a bicyclo[1.1.1]pentane as a phenyl replacement within an LpPLA2 inhibitor
We describe the incorporation of a bicyclo[1.1.1]pentane moiety within two known LpPLA2 inhibitors to act as bioisosteric phenyl replacements. An efficient synthesis to the target compounds was enabled with a dichlorocarbene insertion into a bicyclo[1.1.0]butane system being the key transformation. Potency, physicochemical, and X-ray crystallographic data were obtained to compare the known inhibitors to their bioisosteric counterparts, which showed the isostere was well tolerated and positively impacted on the physicochemical profile
Prospective multi-center study of oncologic outcomes of robot-assisted partial nephrectomy for pT1 renal cell carcinoma
BACKGROUND: Partial nephrectomy has been increasingly recommended over radical nephrectomy for the management of small renal masses based on improved renal functional outcomes without sacrifice of oncologic effectiveness. Robot-assisted partial nephrectomy (RAPN) has been introduced in an effort to offer another minimally invasive option for nephron-sparing surgery. However, reports of RAPN have been limited to short-term perioperative outcomes. The goal of this study is to report and evaluate the initial oncologic outcomes of RAPN. Utilizing prospectively obtained data on RAPN performed by four surgeons at four separate tertiary care centers, we selected patients with unilateral, localized, non-familial, pathologically-confirmed pT1 renal cell carcinoma and a minimum post-operative follow-up of 12 months. METHODS: Utilizing prospectively obtained data on RAPN performed by four surgeons at four separate tertiary care centers, we selected patients with unilateral, localized, non-familial, pathologically-confirmed pT1 renal cell carcinoma and a minimum post-operative follow-up of 12 months. Survival analysis (disease-free, cancer-specific, and overall survival) was performed, and Kaplan-Meier curves were generated. RESULTS: RAPN was performed in 124 patients with a median tumor size of 3.0 cm (IQR 2.2-4.2 cm). Median follow-up was 29 months (range 12-46 months). Positive parenchymal surgical margins occurred in two patients (1.6 %), both of whom were recurrence-free at 30 and 34 months after surgery. The three-year Kaplan-Meier estimated disease-free survival was 94.9 %, cancer-specific survival was 99.1 %, and overall survival was 97.3 %. CONCLUSIONS: In our cohort of patients with small renal carcinomas who were followed for a median of 29 months, recurrence and survival outcomes were similar to those reported for open and laparoscopic partial nephrectomy. Further long-term outcomes will be needed to definitively claim that RAPN is oncologically equivalent to other surgical approaches
IL‐4 induces proliferation in prostate cancer PC3 cells under nutrient‐depletion stress through the activation of the JNK‐pathway and survivin up‐regulation
Interleukin (IL)‐4 plays a critical role in the regulation of immune responses and has been detected at high levels in the tumor microenvironment of cancer patients where it correlates with the grade of malignancy. The direct effect of IL‐4 on cancer cells has been associated with increased cell survival; however, its role in cancer cell proliferation and related mechanisms is still unclear. Here it was shown that in a nutrient‐depleted environment, IL‐4 induces proliferation in prostate cancer PC3 cells. In these cells, under nutrient‐depletion stress, IL‐4 activates mitogen‐activated protein kinases (MAPKs), including Erk, p38, and JNK. Using MAP‐signaling‐specific inhibitors, it was shown that IL‐4‐induced proliferation is mediated by JNK activation. In fact, JNK‐inhibitor‐V (JNKi‐V) stunted IL‐4‐mediated cell proliferation. Furthermore, it was found that IL‐4 induces survivin up‐regulation in nutrient‐depleted cancer cells. Using survivin‐short‐hairpin‐RNAs (shRNAs), it was demonstrated that in this milieu survivin expression above a threshold limit is critical to the mechanism of IL‐4‐mediated proliferation. In addition, the significance of survivin up‐regulation in a stressed environment was assessed in prostate cancer mouse xenografts. It was found that survivin knockdown decreases tumor progression in correlation with cancer cell proliferation. Furthermore, under nutrient depletion stress, IL ‐4 could induce proliferation in cancer cells from multiple origins: MDA‐MB‐231 (breast), A253 (head and neck), and SKOV‐3 (ovarian). Overall, these findings suggest that in a tumor microenvironment under stress conditions, IL‐4 triggers a simultaneous activation of the JNK‐pathway and the up‐regulation of survivin turning on a cancer proliferation mechanism. J. Cell. Biochem. 113: 1569–1580, 2012. © 2011 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90542/1/24025_ftp.pd
Vacuum local and global electromagnetic self-energies for a point-like and an extended field source
We consider the electric and magnetic energy densities (or equivalently field
fluctuations) in the space around a point-like field source in its ground
state, after having subtracted the spatially uniform zero-point energy terms,
and discuss the problem of their singular behavior at the source's position. We
show that the assumption of a point-like source leads, for a simple Hamiltonian
model of the interaction of the source with the electromagnetic radiation
field, to a divergence of the renormalized electric and magnetic energy density
at the position of the source. We analyze in detail the mathematical structure
of such singularity in terms of a delta function and its derivatives. We also
show that an appropriate consideration of these singular terms solves an
apparent inconsistency between the total field energy and the space integral of
its density. Thus the finite field energy stored in these singular terms gives
an important contribution to the self-energy of the source. We then consider
the case of an extended source, smeared out over a finite volume and described
by an appropriate form factor. We show that in this case all divergences in
local quantities such as the electric and the magnetic energy density, as well
as any inconsistency between global and space-integrated local self-energies,
disappear.Comment: 8 pages. The final publication is available at link.springer.co
Red-Cockaded Woodpecker Status and Management: West Gulf Coastal Plain and Interior Highlands
Red-cockaded woodpecker populations declined precipitously following European settlement and expansion and cutting of the original pine forests across the southeastern United States. By 1990 most residual populations lacked demographic viability, existed in degraded habitat, and were isolated from other populations. The primary causes of this situation were harvest of the original pine forests of the southeastern United States, conversion of forested lands to other uses, short-rotation silvicultural practices, and alteration of the fire regime in the regenerated forests. As social and legal mandates changed, management of red-cockaded woodpeckers became a higher priority. Intensive management for red-cockaded woodpeckers is currently practiced on most public and a few private lands that still support populations. Recent population trends and the current status of red-cockaded woodpeckers in Oklahoma, Arkansas, Texas, and Louisiana reflect historical factors and the efficacy of recent management
Fish Distribution in the Skunk River below Ames, Iowa
The Skunk River has been straightened most of the way from Ames to Colfax. In the summer of 1968, 24 species of fish were collected. There were few species other than minnows, and red shiner (Notropis lutrensis), bigmouth shiner (N. dorsalis) and sand shiner (N. straminous) were most abundant. Water levels were above normal during the study and effects of pollution upon fish distribution were not pronounced. The diversity index, d, at the station where treated-sewage wastes entered, was lower than at stations up and down stream but was higher than at the four stations farthest downstream. Uniformity of habitat resulting from stream-straightening probably limits species diversity
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