Density Matrix Renormalization Group and Reaction-Diffusion Processes

The density matrix renormalization group (DMRG) is applied to some one-dimensional reaction-diffusion models in the vicinity of and at their critical point. The stochastic time evolution for these models is given in terms of a non-symmetric ``quantum Hamiltonian'', which is diagonalized using the DMRG method for open chains of moderate lengths (up to about 60 sites). The numerical diagonalization methods for non-symmetric matrices are reviewed. Different choices for an appropriate density matrix in the non-symmetric DMRG are discussed. Accurate estimates of the steady-state critical points and exponents can then be found from finite-size scaling through standard finite-lattice extrapolation methods. This is exemplified by studying the leading relaxation time and the density profiles of diffusion-annihilation and of a branching-fusing model in the directed percolation universality class.Comment: 16 pages, latex, 5 PostScript figures include

Fremdvergabe von IT-Dienstleistungen aus personalwirtschaftlicher Sicht

Die Nutzung von Informationstechnologie (IT) nimmt weiter zu. Gleichzeitig besteht ein Mangel an Fachkräften. Da spezialisierte IT-Unternehmen Vorteile bei der Akquisition dieser Mitarbeiter haben, wirkt sich der Mangel an Spezialisten positiv auf das Ausmaß des Outsourcing von IT-Dienstleistungen aus. Auch andere personalwirtschaftliche Aspekte sollten einen starken Einfluss zeigen. In diesem Artikel werden zuerst die personalwirtschaftlichen Bestimmungsfaktoren der IT-Outsourcing-Entscheidung systematisiert. Es folgt eine deskriptive Analyse von IT-Fremdvergabeentscheidungen und der IT-Nutzung des Wirtschaftszweigs "Unternehmensnahe Dienstleistungen". Schließlich werden im Rahmen eines ökonometrischen Modells die Bestimmungsfaktoren von IT-Outsourcing in dieser Branche untersucht. Es zeigt sich, dass personalwirtschaftliche Variablen einen hohen Erklärungsbeitrag liefern. Die Resultate lassen sich u.a. als Beleg für strategische Komplementarität zwischen verschiedenen Outsourcing-Entscheidungen interpretieren

Fremdvergabe von IT-Dienstleistungen aus personalwirtschaftlicher Sicht

Dieser Beitrag untersucht die personalwirtschaftlichen Aspekte der Fremdvergabe von IT-Leistungen. Er bietet einen systematischen Überblick über bestehende theoretische und empirische Arbeiten zum Thema IT-Outsourcing und legt dabei einen besonderen Schwerpunkt auf die personalwirtschaftlichen Komponenten der ITFremdvergabeentscheidung. Aus dem Überblick werden Hypothesen hinsichtlich der Wirkungsrichtung verschiedener Determinanten des IT-Outsourcings abgeleitet. Diese Hypothesen werden einem empirischen Test unterzogen. Auf Grundlage eines großzahligen Datensatzes (N=679) wird die Fremdvergabeentscheidung von (i) Betreuung und Wartung von Hard- und Software, (ii) Programmierleistungen und (iii) EDV-Schulungen analysiert. Die Schätzergebnisse zeigen, dass personalwirtschaftliche Variablen wie Weiterbildung, Mangel an qualifizierten Mitarbeitern, Qualifikationsniveau der Mitarbeiter und Unternehmensgröße einen hohen Erklärungsbeitrag liefern. Unsere Resultate lassen sich u.a. als Beleg für strategische Komplementarität zwischen verschiedenen Outsourcing-Entscheidungen interpretieren. -- This paper analyzes those aspects of IT outsourcing decisions that are related to personnel economics. It offers a systematic overview of existing theoretical and empirical studies on that issue. We draw empirically testable hypotheses from our overview and take them to data. Based on a comparatively large data set that comprises of 679 obser-vations, we estimate the determinants of outsourcing (i) hardware and software admini-stration and maintenance, (ii) programming services and (iii) IT training. The estimation results indicate that variables such as training, lack of qualified employees, skill structure of employees, and firm size have significant effects on the decision to outsource IT services. Our results also suggest that strategic complementarities exist between the various outsourcing decisions.

Are Treatment Preferences Relevant in Response to Serotonergic Antidepressants and Cognitive-Behavioral Therapy in Depressed Primary Care Patients? Results from a Randomized Controlled Trial Including a Patients' Choice Arm

Background Little is known about the influence of depressed patients' preferences and expectations about treatments upon treatment outcome We investigated whether better clinical outcome in depressed primary care patients is associated with receiving their preferred treatment Methods Within a randomized placebo-controlled single-centre 10-week trial with 5 arms (sertraline, placebo, cognitive-behavioral group therapy, CBT-G, moderated self-help group control, treatment with sertraline or CBT-G according to patients' choice), outcomes for 145 primary care patients with mild-to-moderate depressive disorders according to DSM-IV criteria were investigated Preference for medication versus psychotherapy was assessed at screening using a single item Post-baseline difference scores for the Hamilton Depression Rating Scale (HAMD-17) were used to assess treatment outcome (mixed-model repeated-measures regression analysis) Results Depressed patients receiving their preferred treatment (n = 63), whether sertraline or CBT-G, responded significantly better than those who did not receive their preferred therapy (n = 54, p = 0 001) The difference in outcome between both groups was 8 0 points on the HAMD-17 for psychotherapy and 2 9 points on the HAMD-17 for treatment with antidepressants Results were not explained by differences in depression severity or dropout rates Conclusions Patients' relative preference for medication versus psychotherapy should be considered when offering a treatment because receiving the preferred treatment conveys an additional and clinically relevant benefit (HAMD-17 +2 9 points for drugs, +8 0 points for CBT-G) in outcome Copyright (C) 2010 S Karger AG Base

Reduced inclination of cervical spine in a novel notebook screen system : implications for rehabilitation

Background: Professional working at computer notebooks is associated with high requirements on the body posture in the seated position. By the high continuous static muscle stress resulting from this position at notebooks, professionals frequently working at notebooks for long hours are exposed to an increased risk of musculoskeletal complaints. Especially in subjects with back pain, new notebooks should be evaluated with a focus on rehabilitative issues. Methods: In a field study a new notebook design with adjustable screen was analyzed and compared to standard notebook position. Results: There are highly significant differences in the visual axis of individuals who are seated in the novel notebook position in comparison to the standard position. Also, differences are present between further alternative notebook positions. Testing of gender and glasses did not reveal influences. Conclusion: This study demonstrates that notebooks with adjustable screen may be used to improve the posture. Future studies may focus on patients with musculoskeletal diseases

Ageing phenomena without detailed balance: the contact process

The long-time dynamics of the 1D contact process suddenly brought out of an uncorrelated initial state is studied through a light-cone transfer-matrix renormalisation group approach. At criticality, the system undergoes ageing which is characterised through the dynamical scaling of the two-times autocorrelation and autoresponse functions. The observed non-equality of the ageing exponents a and b excludes the possibility of a finite fluctuation-dissipation ratio in the ageing regime. The scaling form of the critical autoresponse function is in agreement with the prediction of local scale-invariance.Comment: 20 pages, 15 figures, Latex2e with IOP macro

Iron Chelation in Patients with Myelodysplastic Syndromes and Myeloproliferative Neoplasms—Real-World Data from the German Noninterventional Study EXCALIBUR

Myelodysplastic syndromes and myeloproliferative neoplasms both represent hematologic diseases associated with bone marrow failure often resulting in anemia. For those patients, transfusion of red blood cell (RBC) units is essential but results in iron overload (IOL) that may affect various organ functions. Therefore, iron chelation therapy plays a major role in anemic patients, not only because it reduces IOL, but also because it may improve hematopoietic function by increasing hemoglobin or diminishing the requirement for RBC transfusions. To assess the utility, efficacy, and safety of the different iron chelation medications approved in Germany, as well as to examine the effect of chelation on hematopoietic insufficiency, a prospective, multicenter, noninterventional study named EXCALIBUR was designed. In total, 502 patients from 106 German hospitals and medical practices were enrolled. A large proportion of patients switched from a deferasirox dispersible tablet to a deferasirox-film-coated tablet, mainly because of more convenient application, which was reflected in the treatment satisfaction questionnaire for medication scores. Iron chelation was effective in lowering serum ferritin levels, with the observed adverse drug reactions being in line with the known safety profile. Hematologic response occurred in a few patients, comparable to other studies that examined hematologic improvement in patients with MDS

Bis{1-[2-(diphenyl­phosphino)­ethyl]-3-ethylimidazol-2-yl­idene}palladium(II) bis­(hexa­fluoridophosphate) acetonitrile 2.85-solvate

In the structure of the title compound, [Pd(C19H21N2P)2](PF6)2·2.85CH3CN, the two six-membered NHC-phosphane chelate rings form a distorted square-planar coordination geometry around the PdII atom, which lies 0.212 (1) Å above the coordination plane. The sum of the bond angles at PdII is 358.3°, with C—Pd—P bite angles of 84.03 (10) and 83.54 (9)°. The structure includes three acetonitrile solvent mol­ecules, one with partial site occupation and one with severe disorder, which was eventually excluded from the refinement