2,439 research outputs found
Dependency theory and Eastern bloc trade: reformulating a forgotten paradigm
This thesis is concerned with the intentions and effects of subsidised trade within the Eastern bloc. It argues that the core Soviet objective in Eastern Europe from the Thaw onwards was not exploitation for economic gain; subsidisation in return for political concessions; or an ideologically-driven desire for socialist integration, but instead to secure the dependence of the smaller socialist economies on the USSR. It is argued that advances can be made on existing literature by employing a concept of dependence which is capable of linking-up the primarily political concerns that motivated socialist international economic policy with the economic consequences for development that resulted. In order to accomplish this, a revised version of dependency theory (DT) formed through a critique of classical dependency work is used.
DT is proposed as a starting-point for two reasons: firstly it was concerned to look at the interrelation between international processes and national development, a notable absence from the literature on Eastern bloc trade, and secondly the subsidised nature of this trade seems to beg the application of a theory which stresses the significance of international political and economic asymmetries.
The type of dependency analysis proposed here differs from classical DT in several ways, most centrally in that an ideal-typical approach is used which allows for open-ended investigation of reciprocal influence between centre/periphery, as well as the recognition of significant differences between Soviet-type and developed market economies by refraining from making positive statements about either the nature of centre/periphery in themselves or their interactions. The impetus for this reformulation comes from the result of the literature review that some concept of dependence could help to fully articulate the consequences for development of Eastern bloc trade relations in the context of East-West antagonism
Statistical mechanics of strong and weak point vortices in a cylinder
The motion of one-hundred point vortices in a circular cylinder is simulated
numerically and compared with theoretical predictions based on statistical
mechanics. The novel aspect considered here is that the vortices have greatly
different circulation strengths. As envisaged by Onsager, such an arrangement
leads to a substantial amplification of statistical trends such as the
preferred clustering of the strong vortices in either same-signed or
oppositely-signed pairs, depending on the overall energy level. A
microcanonical ensemble based on the conserved total energy E and angular
momentum M for the whole vortex system is then used, in which the few strong
vortices are treated as a subsystem in contact with a reservoir composed of the
many weak vortices. It is shown that allowing for the finite size of this
reservoir is essential in order to predict the statistics of the strong
vortices accurately. Notably, this goes beyond the standard canonical ensemble
with positive or negative temperature. A certain approximation is then shown to
allow a single random sample of uniformly distributed vortex configurations to
be used to predict the strong vortex statistics for all possible values of E
and M. Detailed predictions for distribution functions are then made for
comparison with three simulated cases of near-zero M and low, neutral, or high
E. It is found that the statistical mechanics predictions compare remarkably
well with the numerical results, including a prediction of vortex accumulation
at the cylinder wall for low values of E.Comment: In press, Physics of Fluid
Slow transport by continuous time quantum walks
Continuous time quantum walks (CTQW) do not necessarily perform better than
their classical counterparts, the continuous time random walks (CTRW). For one
special graph, where a recent analysis showed that in a particular direction of
propagation the penetration of the graph is faster by CTQWs than by CTRWs, we
demonstrate that in another direction of propagation the opposite is true; In
this case a CTQW initially localized at one site displays a slow transport. We
furthermore show that when the CTQW's initial condition is a totally symmetric
superposition of states of equivalent sites, the transport gets to be much more
rapid.Comment: 5 pages, 7 figures, accepted for publication in Phys. Rev.
Dissipative Dynamics with Trapping in Dimers
The trapping of excitations in systems coupled to an environment allows to
study the quantum to classical crossover by different means. We show how to
combine the phenomenological description by a non-hermitian Liouville-von
Neumann Equation (LvNE) approach with the numerically exact path integral
Monte-Carlo (PIMC) method, and exemplify our results for a system of two
coupled two-level systems. By varying the strength of the coupling to the
environment we are able to estimate the parameter range in which the LvNE
approach yields satisfactory results. Moreover, by matching the PIMC results
with the LvNE calculations we have a powerful tool to extrapolate the
numerically exact PIMC method to long times.Comment: 5 pages, 2 figure
Lagrangian Investigation of Two-Dimensional Decaying Turbulence
We present a numerical investigation of two-dimensional decaying turbulence
in the Lagrangian framework. Focusing on single particle statistics, we
investigate Lagrangian trajectories in a freely evolving turbulent velocity
field. The dynamical evolution of the tracer particles is strongly dominated by
the emergence and evolution of coherent structures. For a statistical analysis
we focus on the Lagrangian acceleration as a central quantity. For more
geometrical aspects we investigate the curvature along the trajectories. We
find strong signatures for self-similar universal behavior
Generation of continuous variable Einstein-Podolsky-Rosen entanglement via the Kerr nonlinearity in an optical fiber
We report on the generation of a continuous variable Einstein-Podolsky-Rosen (EPR) entanglement using an optical fiber interferometer. The Kerr nonlinearity in the fiber is exploited for the generation of two independent squeezed beams. These interfere at a beam splitter and EPR entanglement is obtained between the output beams. The correlation of the amplitude (phase) quadratures is measured to be 4.0±0.2 (4.0±0.4)dB below the quantum noise limit. The sum criterion for these squeezing variances 0.80±0.03<2 verifies the nonseparability of the state. The product of the inferred uncertainties for one beam (0.64±0.08) is well below the EPR limit of unity
A molecular dynamics view of hysteresis and functional fatigue in martensitic transformations
Shape memory alloys (SMA) exhibit a number of features which are not easily explained by equilibrium thermodynamics, including hysteresis in the phase transformation and ?reverse? shape memory in the high symmetry phase. Processing can change these features: repeated cycling can ?train? the reverse shape memory effect, while changing the amount of hysteresis and other functional properties. These effects are likely to be due to creation of persistent localised defects, which are impossible to study using non-atomistic methods. Here we present a molecular dynamics simulation study of this behaviour. To ensure the largest possible system size, we use a two dimensional binary Lennard-Jones model, which represents a reliable qualitative model system for martensite/austenite transformations. The evolution of the defect structure and its excess energy is investigated in simulations of cyclic transformation/ reverse transformation processes with 160,000 atoms. The simulations show that the transformation proceeds by non-diffusive nucleation and growth processes and produces distinct microstructure. Upon transformation, lattice defects are generated which affect subsequent transformations and vary the potential energy landscape of the sample. Some of the defects persist through the transformation, providing nucleation centres for subsequent cycles. Such defects may provide a memory of previous structures, and thereby may be the basis of a reversible shape memory effect
Changes in the attractiveness of medical careers and career determinants during the bachelor's program at Zurich medical schools
BACKGROUND: Monitoring the career intentions of medical students during their undergraduate studies could help to address the shortage of physicians, particularly in general practice. This study aimed to investigate changes in medical students' career openness, attractiveness and determinants of medical career choice during their bachelor's studies. METHODS: The design was cross-sectional, recruiting all medical students who started a bachelor's program in one of the four different educational tracks in Zurich, Switzerland, in the fall of 2019 (first survey) and completed it in the summer of 2022 (second survey). Students' perceptions of the attractiveness and determinants of different medical career options were assessed using a structured online questionnaire. Absolute changes between the two-time points were reported in percentage points overall and by educational track. Regression analysis was used to examine the association of student characteristics and determinants of career options with the attractiveness of each option. RESULTS: We surveyed 354 medical students at the beginning and 433 at the end of the bachelor's program (participation rate: 71.1% and 86.9%, respectively). Overall, the proportion of students open to all proposed medical career options decreased (from 52.8% to 43.8%, p = 0.004). The attractiveness of outpatient gynecology or pediatrics increased (from 27.4% to 43.4%, p < 0.001), whereas the attractiveness of both general and specialized inpatient care decreased (from 47.8% to 40.3%, p = 0.05 and from 71.1% to 61.1%, p = 0.006 respectively). There was an increase in the proportion of students who perceived part-time work, autonomy and relationships with patients as important career determinants (from 47.3% to 64.7%, p < 0.001; from 63.3% to 77.8%, p < 0.001; from 80.8% to 89.3%, p = 0.002 respectively), while the importance of reputation and career opportunities decreased (from 42.6% to 26.2%, p < 0.001; from 79.2% to 63.6%, p < 0.001 respectively). The importance of part-time work and relationships with patients were positively associated with the attractiveness of general practice. CONCLUSIONS: During the bachelor's program, the attractiveness of a career in general practice tended to decrease, but the importance of part-time work, autonomy and relationships with patients as career determinants increased. Helping students understand how these determinants relate to general practice may increase their interest in the profession
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Long-Term Experience of Chemoradiotherapy Combined with Deep Regional Hyperthermia for Organ Preservation in High-Risk Bladder Cancer (Ta, Tis, T1, T2).
BackgroundThe aim of this study was to evaluate the efficacy and safety of chemoradiotherapy (RCT) combined with regional deep hyperthermia (RHT) of high-risk bladder cancer after transurethral resection of bladder tumor (TUR-BT).Materials and methodsBetween 1982 and 2016, 369 patients with pTa, pTis, pT1, and pT2 cN0-1 cM0 bladder cancer were treated with a multimodal treatment after TUR-BT. All patients received radiotherapy (RT) of the bladder and regional lymph nodes. RCT was administered to 215 patients, RCT + RHT was administered to 79 patients, and RT was used in 75 patients. Treatment response was evaluated 4-6 weeks after treatment with TUR-BT.ResultsComplete response (CR) overall was 83% (290/351), and in treatment groups was RT 68% (45/66), RCT 86% (178/208), and RCT + RHT 87% (67/77). CR was significantly improved by concurrent RCT compared with RT (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.05-5.12; p = .037), less influenced by hyperthermia (OR, 2.56; 95% CI, 0.88-8.00; p = .092). Overall survival (OS) after RCT was superior to RT (hazard ratio [HR], 0.7; 95% CI, 0.50-0.99; p = .045). Five-year OS from unadjusted Kaplan-Meier estimates was RCT 64% versus RT 45%. Additional RHT increased 5-year OS to 87% (HR, 0.32; 95% CI, 0.18-0.58; p = .0001). RCT + RHT compared with RCT showed a significantly better bladder-preservation rate (HR, 0.13; 95% CI, 0.03-0.56; p = .006). Median follow-up was 71 months. The median number of RHT sessions was five.ConclusionThe multimodal treatment consisted of a maximal TUR-BT followed by RT; concomitant platinum-based chemotherapy combined with RHT in patients with high-grade bladder cancer improves local control, bladder-preservation rate, and OS. It offers a promising alternative to surgical therapies like radical cystectomy.Implications for practiceRadical cystectomy with appropriate lymph node dissection has long represented the standard of care for muscle-invasive bladder cancer in medically fit patients, despite many centers reporting excellent long-term results for bladder preserving strategies. This retrospective analysis compares different therapeutic modalities in bladder-preservation therapy. The results of this study show that multimodal treatment consisting of maximal transurethral resection of bladder tumor followed by radiotherapy, concomitant platinum-based chemotherapy combined with regional deep hyperthermia in patients with Ta, Tis, T1-2 bladder carcinomas improves local control, bladder-preservation rate, and survival. More importantly, these findings offer a promising alternative to surgical therapies like radical cystectomy. The authors hope that, in the future, closer collaboration between urologists and radiotherapists will further improve treatments and therapies for the benefit of patients
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