1,450 research outputs found
The Bulk Motion of Flat Edge-On Galaxies Based on 2MASS Photometry
We report the results of applying the 2MASS Tully-Fisher (TF) relations to
study the galaxy bulk flows. For 1141 all-sky distributed flat RFGC galaxies we
construct J, H, K_s TF relations and find that Kron magnitudes show
the smallest dispersion on the TF diagram. For the sample of 971 RFGC galaxies
with V_{3K} < 18000 km/s we find a dispersion and an
amplitude of bulk flow V= 199 +/-61 km/s, directed towards l=301 degr +/-18
degr, b=-2 degr +/-15 degr. Our determination of low-amplitude coherent flow is
in good agreement with a set of recent data derived from EFAR, PSCz, SCI/SCII
samples. The resultant two- dimensional smoothed peculiar velocity field traces
well the large-scale density variations in the galaxy distributions. The
regions of large positive peculiar velocities lie in the direction of the Great
Attractor and Shapley concentration. A significant negative peculiar velocity
is seen in the direction of Bootes and in the direction of the Local void. A
small positive peculiar velocity (100 -- 150 km/s) is seen towards the
Pisces-Perseus supercluster, as well as the Hercules - Coma - Corona Borealis
supercluster regions.Comment: 10 pages, 5 figures. A&A/2003/3582 accepted 15.05.200
UvA-DARE (Digital Academic Repository) Translation and validation of the EORTC brain cancer module (EORTC QLQ-BN20) for use in Iran
Validation and reliability of the Dutch version of the EORTC QLQ-BLM30 module for assessing the health-related quality of life of patients with muscle invasive bladder cancer
Background: Quality of Life (QoL) of bladder cancer patients has been largely neglected. This is partly due to the lack of well-validated QoL questionnaires. The aim of this study is to examine the structural validity, reliability (i.e., internal consistency and test-retest reliability), construct validity (i.e., divergent validity and known group validity) and responsiveness of the Dutch version of the European Organisation for Research and Treatment of Cancer QoL questionnaire for muscle invasive bladder cancer (EORTC-QLQ-BLM30). Methods: Patients with newly diagnosed muscle invasive bladder cancer (MIBC) participating in the population-based ‘Blaaskankerzorg In Beeld’ (BlaZIB) study who completed the EORTC-QLQ-BLM30 at baseline were included. BlaZIB is a Dutch nationwide population-based prospective cohort study collecting clinical data and QoL data of bladder cancer patients. QoL is assessed with a self-administered questionnaire at four points in time: 6 weeks (baseline), 6 months, 12 months and 24 months after diagnosis. Confirmatory factor analysis and multitrait scaling analysis were used to investigate and adapt the scale structure. Reliability, construct validity and responsiveness of the revised scales were evaluated. Results: Of the 1542 patients invited to participate, 650 patients (42.2%) completed the QLQ-BLM30 at baseline. The questionnaire’s scale structure was revised into seven scales and eight single items. Internal consistency and test-reliability were adequate for most scales (Cronbach’s α ≥0.70 and intraclass correlation coefficient ≥ 0.70, respectively), with the exception of the revised urostomy problem scale and abdominal bloating and flatulence scale. The questionnaire exhibited little overlap with the EORTC-QLQ-C30: all correlations were < 0.40, except for the correlation between emotional function (QLQ-C30) and future worries (QLQ-BLM30). The questionnaire was able to distinguish between patient subgroups formed on the basis of physical function, but not – as hypothesized– based on stage. Changes in health due to treatment were captured by the questionnaire, indicating that the questionnaire is responsive to change. Conclusions: This study shows that the adapted scale structure of the EORTC-QLQ-BLM30 generally exhibits good measurement properties in Dutch patients, but needs to be validated in other languages and settings. Trial registration: BlaZIB, NL8106, www.trialregister.nl.</p
Validation and reliability of the Dutch version of the EORTC QLQ-BLM30 module for assessing the health-related quality of life of patients with muscle invasive bladder cancer
Background: Quality of Life (QoL) of bladder cancer patients has been largely neglected. This is partly due to the lack of well-validated QoL questionnaires. The aim of this study is to examine the structural validity, reliability (i.e., internal consistency and test-retest reliability), construct validity (i.e., divergent validity and known group validity) and responsiveness of the Dutch version of the European Organisation for Research and Treatment of Cancer QoL questionnaire for muscle invasive bladder cancer (EORTC-QLQ-BLM30). Methods: Patients with newly diagnosed muscle invasive bladder cancer (MIBC) participating in the population-based ‘Blaaskankerzorg In Beeld’ (BlaZIB) study who completed the EORTC-QLQ-BLM30 at baseline were included. BlaZIB is a Dutch nationwide population-based prospective cohort study collecting clinical data and QoL data of bladder cancer patients. QoL is assessed with a self-administered questionnaire at four points in time: 6 weeks (baseline), 6 months, 12 months and 24 months after diagnosis. Confirmatory factor analysis and multitrait scaling analysis were used to investigate and adapt the scale structure. Reliability, construct validity and responsiveness of the revised scales were evaluated. Results: Of the 1542 patients invited to participate, 650 patients (42.2%) completed the QLQ-BLM30 at baseline. The questionnaire’s scale structure was revised into seven scales and eight single items. Internal consistency and test-reliability were adequate for most scales (Cronbach’s α ≥0.70 and intraclass correlation coefficient ≥ 0.70, respectively), with the exception of the revised urostomy problem scale and abdominal bloating and flatulence scale. The questionnaire exhibited little overlap with the EORTC-QLQ-C30: all correlations were < 0.40, except for the correlation between emotional function (QLQ-C30) and future worries (QLQ-BLM30). The questionnaire was able to distinguish between patient subgroups formed on the basis of physical function, but not – as hypothesized– based on stage. Changes in health due to treatment were captured by the questionnaire, indicating that the questionnaire is responsive to change. Conclusions: This study shows that the adapted scale structure of the EORTC-QLQ-BLM30 generally exhibits good measurement properties in Dutch patients, but needs to be validated in other languages and settings. Trial registration: BlaZIB, NL8106, www.trialregister.nl.</p
Revisiting consistency conditions for quantum states of systems on closed timelike curves: an epistemic perspective
There has been considerable recent interest in the consequences of closed
timelike curves (CTCs) for the dynamics of quantum mechanical systems. A vast
majority of research into this area makes use of the dynamical equations
developed by Deutsch, which were developed from a consistency condition that
assumes that mixed quantum states uniquely describe the physical state of a
system. We criticise this choice of consistency condition from an epistemic
perspective, i.e., a perspective in which the quantum state represents a state
of knowledge about a system. We demonstrate that directly applying Deutsch's
condition when mixed states are treated as representing an observer's knowledge
of a system can conceal time travel paradoxes from the observer, rather than
resolving them. To shed further light on the appropriate dynamics for quantum
systems traversing CTCs, we make use of a toy epistemic theory with a strictly
classical ontology due to Spekkens and show that, in contrast to the results of
Deutsch, many of the traditional paradoxical effects of time travel are
present.Comment: 10 pages, 6 figures, comments welcome; v2 added references and
clarified some points; v3 published versio
Peculiar Velocities of 3000 Spiral Galaxies from the 2MFGC Catalog
The 2MFGC catalog we have used contains 18020 galaxies selected from the
extended objects in the 2MASS infrared sky survey as having apparent ratios of
the axes b/a<0.3. Most of them are spiral galaxies of later morphological types
whose disks are seen almost edge-on. The individual distances to the 2724 2MFGC
galaxies with known rotation velocities and radial velocities are determined
using a multiparameter infrared Tully-Fisher relation. A list of the distances
and peculiar velocities of these galaxies is presented. The collective motion
of the 2MFGC galaxies relative to the cosmic microwave background is
characterized by a velocity V = 199 +- 37 km/s in the direction l = 304o +-
11o, b = -8o +- 8o. Our list is currently the most representative and uniform
sample for analyzing non-Hubble motions of galaxies on a scale of ~100 Mpc.Comment: 12 pages, 5 figures, 1 table (here we present the beginning of the
table as an illustration). Astrophysics, Vol. 49, No. 4, 2006. Original
article submitted June 13, 2006. Translated from Astrofizika, Vol. 49, No. 4,
pp. 527-540 (November 2006
Domiciliary chemotherapy with gemcitabine is safe and acceptable to advanced non-small-cell lung cancer patients: results of a feasibility study
Can biological quantum networks solve NP-hard problems?
There is a widespread view that the human brain is so complex that it cannot
be efficiently simulated by universal Turing machines. During the last decades
the question has therefore been raised whether we need to consider quantum
effects to explain the imagined cognitive power of a conscious mind.
This paper presents a personal view of several fields of philosophy and
computational neurobiology in an attempt to suggest a realistic picture of how
the brain might work as a basis for perception, consciousness and cognition.
The purpose is to be able to identify and evaluate instances where quantum
effects might play a significant role in cognitive processes.
Not surprisingly, the conclusion is that quantum-enhanced cognition and
intelligence are very unlikely to be found in biological brains. Quantum
effects may certainly influence the functionality of various components and
signalling pathways at the molecular level in the brain network, like ion
ports, synapses, sensors, and enzymes. This might evidently influence the
functionality of some nodes and perhaps even the overall intelligence of the
brain network, but hardly give it any dramatically enhanced functionality. So,
the conclusion is that biological quantum networks can only approximately solve
small instances of NP-hard problems.
On the other hand, artificial intelligence and machine learning implemented
in complex dynamical systems based on genuine quantum networks can certainly be
expected to show enhanced performance and quantum advantage compared with
classical networks. Nevertheless, even quantum networks can only be expected to
efficiently solve NP-hard problems approximately. In the end it is a question
of precision - Nature is approximate.Comment: 38 page
Peculiar Motions in the Region of the Ursa Major Supercluster of Galaxies
We have investigated the peculiar motions of clusters of galaxies in the Ursa
Major (UMa) supercluster and its neighborhood. Based on SDSS (Sloan Digital Sky
Survey) data, we have compiled a sample of early-type galaxies and used their
fundamental plane to determine the cluster distances and peculiar velocities.
The samples of early-type galaxies in the central regions (within R_200) of 12
UMa clusters of galaxies, in three main subsystems of the supercluster -- the
filamentary structures connecting the clusters, and in nine clusters from the
nearest UMa neighborhood have similar parameters. The fairly high overdensity
(3 by the galaxy number and 15 by the cluster number) suggests that the
supercluster as a whole is gravitationally bound, while no significant peculiar
motions have been found: the peculiar velocities do not exceed the measurement
errors by more than a factor of 1.5-2. The mean random peculiar velocities of
clusters and the systematic deviations from the overall Hubble expansion in the
supercluster are consistent with theoretical estimates. For the possible
approach of the three UMa subsystems to be confirmed, the measurement accuracy
must be increased by a factor of 2-3.Comment: 21 pages, 4 tables, 7 figure
Bbasic analysis of the scope of patent protection: suggestions from the transaction cost theory
The objective of this study was to evaluate the feasibility, reliability, validity and responsiveness of the HIV Overview of Problems Evaluation System (HOPES) in a Dutch sample. The HOPES was administered three times in a one-year period to a sample of 106 outpatients with a symptomatic HIV-infection (n = 23) or AIDS (n = 83). The HOPES is a self-report HIV-specific quality of life (QOL) questionnaire including five scales: physical, psycho-social and sexual functioning, medical interaction and partner relationship. QOL was also assessed with the EORTC Quality of Life Questionnaire (EORTC QLQ-C30), a 30-item self-report instrument. Clinical data included Centers for Disease Control and Prevention (CDC) stage, date of diagnosis and CD4 cell count. Patients needed approximately 20-30 minutes to complete the questionnaire. The five scales had good internal consistency reliability. Multitrait scaling analysis provided moderate support for item discriminant and convergent validity. The HOPES exhibited adequate levels of construct validity: (1) the inter-scale correlations and correlations with the EORTC QLQ-C30 were in the predicted direction; (2) it discriminated clearly between patients with AIDS and ARC and (3) it was able to document changes in QOL over time. Moreover, the HOPES was responsive to changes in clinical status over time as indicated by CD4 counts. This study provides further evidence of the reliability and validity of the HOPES and shows that this instrument is responsive to changes in CD4 cell count
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