Geometric phase distributions for open quantum systems

In an open system, the geometric phase should be described by a distribution. We show that a geometric phase distribution for open system dynamics is in general ambiguous, but the imposition of reasonable physical constraints on the environment and its coupling with the system yields a unique geometric phase distribution that applies even for mixed states, non-unitary dynamics, and non-cyclic evolutions.Comment: Some minor revisions, references update

Regionalization of Hydrologic Response in the Great Lakes Basin: Considerations of Temporal Scales of Analysis

Methods for predicting streamflow in areas with limited or nonexistent measures of hydrologic response commonly rely on regionalization techniques, where knowledge pertaining to gauged watersheds is transferred to ungauged watersheds. Hydrologic response indices have frequently been employed in contemporary regionalization research related to predictions in ungauged basins. In this study, we developed regionalization models using multiple linear regression and regression tree analysis to derive relationships between hydrologic response and watershed physical characteristics for 163 watersheds in the Great Lakes basin. These models provide an empirical means for simulating runoff in ungauged basins at a monthly time step without implementation of a rainfall-runoff model. For the dependent variable in these regression models, we used monthly runoff ratio as the indicator of hydrologic response and defined it at two temporal scales: (1) treating all monthly runoff ratios as individual observations and (2) using the mean of these monthly runoff ratios for each watershed as a representative observation. Application of the models to 62 validation watersheds throughout the Great Lakes basin indicated that model simulations were far more sensitive to the temporal characterization of hydrologic response than to the type of regression technique employed, and that models conditioned on individual monthly runoff ratios (rather than long term mean values) performed better. This finding is important in light of the increased usage of hydrologic response indices in recent regionalization studies. Models using individual observations for the dependent variable generally simulated monthly runoff with reasonable skill in the validation watersheds (median Nash-Sutcliffe efficiency = 0.53, median R2 = 0.66, median absolute value of deviation of runoff volume = 13%). These results suggest the viability of empirical 3 approaches to simulate runoff in ungauged basins. This finding is significant given the many regions of the world with sparse gaging networks and limited resources for gathering the field data required to calibrate rainfall-runoff models

Geometric phase for nonlinear coherent and squeezed state

The geometric phases for standard coherent states which are widely used in quantum optics have attracted a large amount of attention. Nevertheless, few physicists consider about the counterparts of non-linear coherent states, which are useful in the description of the motion of a trapped ion. In this paper, the non-unitary and non-cyclic geometric phases for two nonlinear coherent and one squeezed states are formulated respectively. Moreover, some of their common properties are discussed respectively, such as gauge invariance, non-locality and non-linear effects. The non-linear functions have dramatic impacts on the evolution of the corresponding geometric phases. They speed the evolution up or down. So this property may have application in controlling or measuring geometric phase. For the squeezed case, when the squeezed parameter r -> \infinity, the limiting value of the geometric phase is also determined by non-linear function at a given time and angular velocity. In addition, the geometric phases for standard coherent and squeezed states are obtained under a particular condition. When the time evolution undergoes a period, their corresponding cyclic geometric phases are achieved as well. And the distinction between the geometric phases of the two coherent states maybe regarded as a geometric criterion

The quantum adiabatic search with decoherence in the instantaneous energy eigenbasis

In Phys. Rev. A {\bf 71}, 060312(R) (2005) the robustness of the local adiabatic quantum search to decoherence in the instantaneous eigenbasis of the search Hamiltonian was examined. We expand this analysis to include the case of the global adiabatic quantum search. As in the case of the local search the asymptotic time complexity for the global search is the same as for the ideal closed case, as long as the Hamiltonian dynamics is present. In the case of pure decoherence, where the environment monitors the search Hamiltonian, we find that the time complexity of the global quantum adiabatic search scales like $N^{3/2}$, where $N$ is the list length. We moreover extend the analysis to include success probabilities $p<1$ and prove bounds on the run time with the same scaling as in the conditions for the $p\to 1$ limit. We supplement the analytical results by numerical simulations of the global and local search.Comment: Material added, journal reference adde

A general treatment of geometric phases and dynamical invariants

Based only on the parallel transport condition, we present a general method to compute Abelian or non-Abelian geometric phases acquired by the basis states of pure or mixed density operators, which also holds for nonadiabatic and noncyclic evolution. Two interesting features of the non-Abelian geometric phase obtained by our method stand out: i) it is a generalization of Wilczek and Zee's non-Abelian holonomy, in that it describes nonadiabatic evolution where the basis states are parallelly transported between distinct degenerate subspaces, and ii) the non-Abelian character of our geometric phase relies on the transitional evolution of the basis states, even in the nondegenerate case. We apply our formalism to a two-level system evolving nonadiabatically under spontaneous decay to emphasize the non-Abelian nature of the geometric phase induced by the reservoir. We also show, through the generalized invariant theory, that our general approach encompasses previous results in the literature

A controlled study of supplementation with essential amino acids and α-keto acids in the conservative management of patients with chronic renal failure

Art und Zusammensetzung einer optimalen eiweißarmen Ernährung für Patienten mit Niereninsuffizienz sind weiterhin umstritten. Die orale medikamentöse Behandlung mit essentiellen Aminosäuren oder α-Ketosäuren wird häufig empfohlen. Unsere Untersuchungen vergleichen nacheinander bei 15 ambulanten Patienten mit chronischem Nierenversagen (mittlere Kreatinin-Clearance 10,8 ml/min) unter einer eiweißarmen Ernährung von 0,57 g/kg Körpergewicht (40 g/70 kg) die Wirkung einer Substitution mit essentiellen Aminosäuren, danach die Substitution mit α-Ketosäuren gegenüber Plazebo. Der nachgewiesene Proteingehalt in der Nahrung betrug 0,55 g/kg, die Energiezufuhr 27 kcal/kg Körpergewicht, wie mehrfach Ernährungsprotokolle über jeweils 7 Tage bei den Patienten zeigen ließen. Nach einer Vorperiode von 6 Wochen nur unter diätetischen Maßnahmen erhielten alle Patienten zusätzlich 0,112 g essentielle Aminosäuren/kg Körpergewicht über 6 Wochen, danach in einer Doppelblinduntersuchung 0,105 g α-Ketosäuren/kg Körpergewicht im Vergleich gegenüber Plazebo, ebenfalls jeweils über 6 Wochen. Nüchtern-Blutuntersuchungen wurden für ein Standard-Laborwertprogramm, insbesondere für 15 Proteinmangelparameter, alle 3 Wochen durchgeführt, ferner anthropometrische und klinische Kontrollen. Die Laborwerte erbrachten keine Hinweise auf einen manifesten Proteinmangel. Die Therapie mit α-Ketosäuren erniedrigte die Phosphatspiegel signifikant (p<0,05). Dagegen konnten weder unter essentiellen Aminosäuren oder α-Ketosäuren andere für den Patienten wesentliche Effekte nachgewiesen werden. Deshalb erscheint uns eine Substitution mit essentiellen Aminosäuren oder Ketosäuren überflüssig bei Patienten mit einer chronischen Niereninsuffizienz, die sich in einem stabilen Stoffwechselgleichgewicht befinden und mit einer Eiweißzufuhr von 0,55 g/kg Körpergewicht behandelt werden. Oral therapy with essential amino acids (EAA) or α-keto acids (α-KA) has been recommended in patients with renal failure, but quality and quantity of optimal protein intake are still controversial. This study compares sequentially the effect of supplementation with EAA, and with α-KA versus placebo in 15 ambulatory patients with chronic renal failure (average creatinine clearance 10.8 ml/min), maintained on a protein diet of 0.57 g/kg body weight (40 g for a 70-kg patient). The actual dietary intake averaged 0.55 g protein/kg and 27 kcal/kg according to repeated 7-day dietary recordings. After a 6-week baseline period on this diet, all patients received additionally 0.112 g EAA/kg for 6 weeks followed by a double-blind cross-over study of 0.105 g α-KA/kg versus placebo supplementation for 6 weeks each. Fasting blood samples for multiple parameters, including 15 indicators for protein deficiency, as well as anthropometric and clinical data were evaluated every 3 weeks. Laboratory data revealed no indications of protein deficiency. Therapy with α-KA diminished serum phosphate concentration (p<0.05), however no other significant beneficial effects could be demonstrated during supplementation with either EAA or α-KA. Therefore, such supplementation to a 0.55-g/kg-protein diet appears superfluous in stable ambulatory patients with renal insufficiency.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41743/1/394_2005_Article_BF02020747.pd

Forty years of carabid beetle research in Europe - from taxonomy, biology, ecology and population studies to bioindication, habitat assessment and conservation

Volume: 100Start Page: 55End Page: 14