1,244 research outputs found
Nurse Manager Transformational Leadership Practices and Patient Outcomes Among Magnet and Non-Magnet Hospitals
In 2004 the Institute Of Medicine called for healthcare leaders to embrace and adopt transformational leadership practices to promote quality of care and favorable patient outcomes. Nurse managers are accountable for 24-hour operations of their departments and influence patient outcomes. The purpose of this research was to examine the relationships among nurse manager transformational leadership practices, patient outcomes and hospital types (Magnet, On The Journey, and Non-Magnet). A correlational study examined relationships between self-reported transformational leadership practices of nurse managers and patient outcomes by hospital types. The study was conducted using a purposive sample of Association of California Nurse Leader membership database. In addition nurse managers at one San Diego based hospital participated in the study after IRB approval was received. The measurement tools utilized for this study include the Leadership Practices Inventory (LPI) and an investigator designed demographic questionnaire. A One-Way ANOVA showed no statistically significant differences in transformational leadership practices of nurse managers among hospital types and patient outcomes. Levene\u27s test confirmed that there were no differences in the mean variances between hospital types. Pearson\u27s correlation was conducted and showed a positive correlation between the LPI sub-scale Encourage Others to Act (EOA) and patient falls that was moderate and statistically significant, r(22)=.421, p\u3c.05; and a positive correlation between the LPI sub-scale Inspire a Shared Vision (ISV), and hospital acquired pressure ulcers was moderate and statistically significant, r(22)=.406, p\u3c.05. A multiple linear regression analysis was conducted to explore to what extent the LPI total scores predicted patient fall rates and HAPU. Nurse manager experience and LPI scores did not account for a significant amount of variance in HAPU rates, F=.666, p=.678, R2=.190. Nurse manager experience and LPI scores did not account for a significant amount of variance in patient falls, F=2.446, p=.069, R2=.463. Further research should explore transformational leadership practices of nurse managers assessed by the staff that report directly to the manager. Nurse managers should eliminate barriers to support the delivery of quality patient care utilizing transactional and transformational leadership practices. A larger sample size is needed to further explore impact of leadership practices and patient outcomes
Decoherence Rates in Large Scale Quantum Computers and Macroscopic Systems
Markovian regime decoherence effects in quantum computers are studied in
terms of the fidelity for the situation where the number of qubits N becomes
large. A general expression giving the decoherence time scale in terms of
Markovian relaxation elements and expectation values of products of system
fluctuation operators is obtained, which could also be applied to study
decoherence in other macroscopic systems such as Bose condensates and
superconductors. A standard circuit model quantum computer involving
three-state lambda system ionic qubits is considered, with qubits localised
around well-separated positions via trapping potentials. The centre of mass
vibrations of the qubits act as a reservoir. Coherent one and two qubit gating
processes are controlled by time dependent localised classical electromagnetic
fields that address specific qubits, the two qubit gating processes being
facilitated by a cavity mode ancilla, which permits state interchange between
qubits. With a suitable choice of parameters, it is found that the decoherence
time can be made essentially independent of N.Comment: Minor revisions. To be published in J Mod Opt. One figur
Effects of Noise, Correlations and errors in the preparation of initial states in Quantum Simulations
In principle a quantum system could be used to simulate another quantum
system. The purpose of such a simulation would be to obtain information about
problems which cannot be simulated with a classical computer due to the
exponential increase of the Hilbert space with the size of the system and which
cannot be measured or controlled in an actual experiment. The system will
interact with the surrounding environment, with the other particles in the
system and be implemented using imperfect controls making it subject to noise.
It has been suggested that noise does not need to be controlled to the same
extent as it must be for general quantum computing. However the effects of
noise in quantum simulations and how to treat them are not completely
understood. In this paper we study an existing quantum algorithm for the
one-dimensional Fano-Anderson model to be simulated using a liquid-state NMR
device. We calculate the evolution of different initial states in the original
model, and then we add interacting spins to simulate a more realistic
situation. We find that states which are entangled with their environment, and
sometimes correlated but not necessarily entangled have an evolution which is
described by maps which are not completely positive. We discuss the conditions
for this to occur and also the implications.Comment: Revtex 4-1, 14 pages, 21 figures, version 2 has typos corrected and
acknowledgement adde
Estimating the Probability of Clonal Relatedness of Pairs of Tumors in Cancer Patients
Next generation sequencing panels are being used increasingly in cancer research to study tumor evolution. A specific statistical challenge is to compare the mutational profiles in different tumors from a patient to determine the strength of evidence that the tumors are clonally related, i.e. derived from a single, founder clonal cell. The presence of identical mutations in each tumor provides evidence of clonal relatedness, although the strength of evidence from a match is related to how commonly the mutation is seen in the tumor type under investigation. This evidence must be weighed against the evidence in favor of independent tumors from non-matching mutations. In this article we frame this challenge in the context of diagnosis using a novel random effects model. In this way, by analyzing a set of tumor pairs, we can estimate the proportion of cases that are clonally related in the sample as well as the individual diagnostic probabilities for each case. The method is illustrated using data from a study to determine the clonal relationship of lobular carcinoma in situ with subsequent invasive breast cancers where each tumor in the pair was subjected to whole exome sequencing. The statistical properties of the method are evaluated using simulations, demonstrating that the key model parameters are estimated with only modest bias in small samples
The impact of a major cluster merger on galaxy evolution in MACS\,J0025.4-1225
We present results of an extensive morphological, spectroscopic, and
photometric study of the galaxy population of MACS J0025.41225 (z=0.586), a
major cluster merger with clear segregation of dark and luminous matter, to
examine the impact of mergers on galaxy evolution. Based on 436 galaxy spectra
obtained with Keck DEIMOS, we identified 212 cluster members within 4 Mpc of
the cluster centre, and classified them using three spectroscopic types; we
find 111 absorption-line, 90 emission-line (including 23 e(a) and 11 e(b)), and
6 E+A galaxies. The fraction of absorption(emission)-line galaxies is a
monotonically increasing(decreasing) function of both projected galaxy density
and radial distance to the cluster center. More importantly, the 6 observed E+A
cluster members are all located between the dark-matter peaks of the cluster
and within ~0.3Mpc radius of the X-ray flux peak, unlike the E+A galaxies in
other intermediate-redshift clusters which are usually found to avoid the core
region. In addition, we use Hubble Space Telescope imaging to classify cluster
members according to morphological type. We find the global fraction of spiral
and lenticular galaxies in MACS J0025 to be among the highest observed to date
in clusters at z>0.5. The observed E+A galaxies are found to be of lenticular
type with Sersic indices of ~2, boosting the local fraction of S0 to 70 per
cent between the dark-matter peaks. Combing the results of our analysis of the
spatial distribution, morphology, and spectroscopic features of the galaxy
population, we propose that the starburst phase of these E+A galaxies was both
initiated and terminated during the first core-passage about 0.5--1Gyr ago, and
that their morphology has already been transformed into S0 due to ram pressure
and/or tidal forces near the cluster core. By contrast, ongoing starbursts are
observed predominantly in infalling galaxies, and thus appears to be unrelated
to the cluster merger.Comment: 18 pages, 17 figures, accepted by MNRA
Viscous regularization and r-adaptive remeshing for finite element analysis of lipid membrane mechanics
As two-dimensional fluid shells, lipid bilayer membranes resist bending and
stretching but are unable to sustain shear stresses. This property gives
membranes the ability to adopt dramatic shape changes. In this paper, a finite
element model is developed to study static equilibrium mechanics of membranes.
In particular, a viscous regularization method is proposed to stabilize
tangential mesh deformations and improve the convergence rate of nonlinear
solvers. The Augmented Lagrangian method is used to enforce global constraints
on area and volume during membrane deformations. As a validation of the method,
equilibrium shapes for a shape-phase diagram of lipid bilayer vesicle are
calculated. These numerical techniques are also shown to be useful for
simulations of three-dimensional large-deformation problems: the formation of
tethers (long tube-like exetensions); and Ginzburg-Landau phase separation of a
two-lipid-component vesicle. To deal with the large mesh distortions of the
two-phase model, modification of vicous regularization is explored to achieve
r-adaptive mesh optimization
Phosphorylation of eIF4GII and 4E-BP1 in response to nocodazole treatment: a reappraisal of translation initiation during mitosis
Translation mechanisms at different stages of the cell cycle have been studied for many years, resulting in the dogma that translation rates are slowed during mitosis, with cap-independent translation mechanisms favored to give expression of key regulatory proteins. However, such cell culture studies involve synchronization using harsh methods, which may in themselves stress cells and affect protein synthesis rates. One such commonly used chemical is the microtubule de-polymerization agent, nocodazole, which arrests cells in mitosis and has been used to demonstrate that translation rates are strongly reduced (down to 30% of that of asynchronous cells). Using synchronized HeLa cells released from a double thymidine block (G 1/S boundary) or the Cdk1 inhibitor, RO3306 (G 2/M boundary), we have systematically re-addressed this dogma. Using FACS analysis and pulse labeling of proteins with labeled methionine, we now show that translation rates do not slow as cells enter mitosis. This study is complemented by studies employing confocal microscopy, which show enrichment of translation initiation factors at the microtubule organizing centers, mitotic spindle, and midbody structure during the final steps of cytokinesis, suggesting that translation is maintained during mitosis. Furthermore, we show that inhibition of translation in response to extended times of exposure to nocodazole reflects increased eIF2α phosphorylation, disaggregation of polysomes, and hyperphosphorylation of selected initiation factors, including novel Cdk1-dependent N-terminal phosphorylation of eIF4GII. Our work suggests that effects on translation in nocodazole-arrested cells might be related to those of the treatment used to synchronize cells rather than cell cycle status
The Role of TLR4 in the Paclitaxel Effects on Neuronal Growth In Vitro
Paclitaxel (Pac) is an antitumor agent that is widely used for treatment of solid cancers. While being effective as a chemotherapeutic agent, Pac in high doses is neurotoxic, specifically targeting sensory innervations. In view of these toxic effects associated with conventional chemotherapy, decreasing the dose of Pac has been recently suggested as an alternative approach, which might limit neurotoxicity and immunosuppression. However, it remains unclear if low doses of Pac retain its neurotoxic properties or might exhibit unusual effects on neuronal cells. The goal of this study was to analyze the concentration-dependent effect of Pac on isolated and cultured DRG neuronal cells from wild-type and TLR4 knockout mice. Three different morphological parameters were analyzed: the number of neurons which developed neurites, the number of neurites per cell and the total length of neurites per cell. Our data demonstrate that low concentrations of Pac (0.1 nM and 0.5 nM) do not influence the neuronal growth in cultures in both wild type and TLR4 knockout mice. Higher concentrations of Pac (1-100 nM) had a significant effect on DRG neurons from wild type mice, affecting the number of neurons which developed neurites, number of neurites per cell, and the length of neurites. In DRG from TLR4 knockout mice high concentrations of Pac showed a similar effect on the number of neurons which developed neurites and the length of neurites. At the same time, the number of neurites per cell, indicating the process of growth cone initiation, was not affected by high concentrations of Pac. Thus, our data showed that Pac in high concentrations has a significant damaging effect on axonal growth and that this effect is partially mediated through TLR4 pathways. Low doses of Pac are devoid of neuronal toxicity and thus can be safely used in a chemomodulation mode. © 2013 Ustinova et al
Verified global optimization for estimating the parameters of nonlinear models
Nonlinear parameter estimation is usually achieved via the minimization of some possibly non-convex cost function. Interval analysis allows one to derive algorithms for the guaranteed characterization of the set of all global minimizers of such a cost function when an explicit expression for the output of the model is available or when this output is obtained via the numerical solution of a set of ordinary differential equations. However, cost functions involved in parameter estimation are usually challenging for interval techniques, if only because of multi-occurrences of the parameters in the formal expression of the cost. This paper addresses parameter estimation via the verified global optimization of quadratic cost functions. It introduces tools for the minimization of generic cost functions. When an explicit expression of the output of the parametric model is available, significant improvements may be obtained by a new box exclusion test and by careful manipulations of the quadratic cost function. When the model is described by ODEs, some of the techniques available in the previous case may still be employed, provided that sensitivity functions of the model output with respect to the parameters are available
Safety and tolerability of sitagliptin in patients with type 2 diabetes: a pooled analysis
<p>Abstract</p> <p>Background</p> <p>Sitagliptin, a highly selective dipeptidyl peptidase-4 inhibitor, is the first in a new class of oral antihyperglycemic agents (AHAs) for the treatment of patients with type 2 diabetes. Type 2 diabetes is a life-long disease requiring chronic treatment and management. Therefore, robust assessment of the long-term safety and tolerability of newer therapeutic agents is of importance. The purpose of this analysis was to assess the safety and tolerability of sitagliptin by pooling 12 large, double-blind, Phase IIb and III studies up to 2 years in duration. Methods: This analysis included 6139 patients with type 2 diabetes receiving either sitagliptin 100 mg/day (N = 3415) or a comparator agent (placebo or an active comparator) (N = 2724; non-exposed group). The 12 studies from which this pooled population was drawn represent the double-blind, randomized, Phase IIB and III studies that included patients treated with the clinical dose of sitagliptin (100 mg/day) for at least 18 weeks up to 2 years and that were available in a single safety database as of November 2007. These 12 studies assessed sitagliptin as monotherapy, initial combination therapy with metformin, or add-on combination therapy with other oral AHAs (metformin, pioglitazone, sulfonylurea, sulfonylurea + metformin, or metformin + rosiglitazone). Patients in the non-exposed group were taking placebo, pioglitazone, metformin, sulfonylurea, sulfonylurea + metformin, or metformin + rosiglitazone. This safety analysis used patient-level data from each study to evaluate clinical and laboratory adverse experiences.</p> <p>Results</p> <p>For clinical adverse experiences, the incidence rates of adverse experiences overall, serious adverse experiences, and discontinuations due to adverse experiences were similar in the sitagliptin and non-exposed groups. The incidence rates of specific adverse experiences were also generally similar in the two groups, with the exception of an increased incidence rate of hypoglycemia observed in the non-exposed group. The incidence rates of drug-related adverse experiences overall and discontinuations due to drug-related adverse experiences were higher in the non-exposed group, primarily due to the increased incidence rate of hypoglycemia in this group. For cardiac- and ischemia-related adverse experiences (including serious events), there were no meaningful between-group differences. No meaningful differences between groups in laboratory adverse experiences, either summary measures or specific adverse experiences, were observed.</p> <p>Conclusion</p> <p>In patients with type 2 diabetes, sitagliptin 100 mg/day was well tolerated in clinical trials up to 2 years in duration.</p
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