Validation of a Clinical Scoring System for Outcome Prediction in Dogs with Acute Kidney Injury Managed by Hemodialysis.

BackgroundA scoring system for outcome prediction in dogs with acute kidney injury (AKI) recently has been developed but has not been validated.HypothesisThe scoring system previously developed for outcome prediction will accurately predict outcome in a validation cohort of dogs with AKI managed with hemodialysis.AnimalsOne hundred fifteen client-owned dogs with AKI.MethodsMedical records of dogs with AKI treated by hemodialysis between 2011 and 2015 were reviewed. Dogs were included only if all variables required to calculate the final predictive score were available, and the 30-day outcome was known. A predictive score for 3 models was calculated for each dog. Logistic regression was used to evaluate the association of the final predictive score with each model's outcome. Receiver operating curve (ROC) analyses were performed to determine sensitivity and specificity for each model based on previously established cut-off values.ResultsHigher scores for each model were associated with decreased survival probability (P < .001). Based on previously established cut-off values, 3 models (models A, B, C) were associated with sensitivities/specificities of 73/75%, 71/80%, and 75/86%, respectively, and correctly classified 74-80% of the dogs.Conclusions and clinical relevanceAll models were simple to apply and allowed outcome prediction that closely corresponded with actual outcome in an independent cohort. As expected, accuracies were slightly lower compared with those from the previously reported cohort used initially to develop the models

The Divergence of Stress and the Principle of Virtual Power on Manifolds

Stresses on manifolds may be introduced from two diflerent points of view. For an m-dimensional material universe, the variational approach regards stresses as fields that associate m-forms, the power densities, with the first jets of generalized velocity fields. In the second approach, the Cauchy approach, stresses are covector valued (m - 1)-forms whose odd restrictions to the the boundary of bodies give the surface forces on them. The relation between the two approaches is studied for general manifolds that are not equipped with a connection

Evaluation of Canine Pancreas-Specific Lipase Activity, Lipase Activity, and Trypsin-Like Immunoreactivity in an Experimental Model of Acute Kidney Injury in Dogs.

BackgroundDiagnosis of pancreatitis in dogs is complicated by extrapancreatic disorders that can alter the results of laboratory tests. Extrapancreatic disorders can also affect the diagnosis of exocrine pancreatic insufficiency (EPI). The effects of acute kidney injury (AKI) on pancreas-specific lipase activity (Spec cPL(®) Test), serum lipase activity and trypsin-like immunoreactivity (TLI) in dogs have not been evaluated.Hypothesis/objectivesSerum Spec cPL, lipase activity, and TLI concentrations will increase secondary to decreased kidney function.AnimalsFive purpose-bred dogs.MethodsExperimental prospective study. Gentamicin was used to induce AKI in 5 purpose-bred dogs. Serum samples were collected for measurement of creatinine, Spec cPL, lipase activity and TLI over 60 days, during both induction of, and recovery from, AKI.ResultsAll dogs developed and recovered from AKI. Six of 52 (12%) serum Spec cPL concentrations were increased (2 in the equivocal zone and 4 consistent with pancreatitis) in 2 of 5 (40%) dogs. Two of 51 (4%) serum lipase activity values were increased in 2 of 5 dogs. Serum TLI was increased above the reference range in 17 of 50 (34%) samples in 3 of 5 dogs. For all biomarkers, there was no consistent correlation with increases in serum creatinine concentration.Conclusions and clinical importanceDecreased renal excretion during experimental AKI did not cause consistent and correlated increases in serum Spec cPL, lipase activity, or TLI in this cohort of dogs

Urinary Neutrophil Gelatinase-associated Lipocalin as a Marker for Identification of Acute Kidney Injury and Recovery in Dogs with Gentamicin-induced Nephrotoxicity.

BackgroundAcute kidney injury (AKI) is associated with high mortality rates in dogs, which may be a consequence of late recognition using traditional diagnostic tests. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein-induced during kidney injury that may identify AKI earlier than traditional tests.Objectives/hypothesisTo evaluate urinary NGAL (uNGAL) and uNGAL-to-urinary creatinine ratio (UNCR) as early markers of kidney injury and recovery in an AKI model in dogs. It was hypothesized that these markers would document AKI earlier than serum creatinine concentration.AnimalsFive purpose-bred dogs.MethodsProspective study. Acute kidney injury, defined as a > 50% increase in serum creatinine concentration above baseline, was induced in dogs by gentamicin administration (8-10 mg/kg SC q8h). Blood and urine collected for biochemical analyses and uNGAL and urinary creatinine concentrations, respectively, during AKI induction and recovery.ResultsAcute kidney injury was diagnosed significantly earlier based on a 7-fold increase in UNCR compared to a > 50% increase in serum creatinine concentration (day 8; range, 2-10 mg/dl vs day 16; range, 14-19 mg/dl; P = .009). During recovery, the initial decrease in UNCR preceded the decrease in serum creatinine concentration by a median of 2 days. The uNGAL changes paralleled UNCR changes, but the increase in uNGAL was triphasic; the initial peak occurred earlier than UNCR (median, day 11 versus median, day 19).Conclusions and clinical importanceThe UNCR was early marker of gentamicin-induced AKI and its decrease documented onset of renal recovery. Additional studies are needed to validate this marker in dogs with naturally occurring renal injury

On the nature of Coulomb corrections to the e^+e^- pair production in ultrarelativistic heavy-ion collisions

We manifest the origin of the wrong conclusion made by several groups of authors on the absence of Coulomb corrections to the cross section of the e^+e^- pair production in ultrarelativistic heavy-ion collisions. The source of the mistake is connected with an incorrect passage to the limit in the expression for the cross section. When this error is eliminated, the Coulomb corrections do not vanish and agree with the results obtained within the Weizs\"acker-Williams approximation.Comment: 7 pages, LaTe

Noise Induced Intermittency in a Superconducting Microwave Resonator

We experimentally and numerically study a NbN superconducting stripline resonator integrated with a microbridge. We find that the response of the system to monochromatic excitation exhibits intermittency, namely, noise-induced jumping between coexisting steady-state and limit-cycle responses. A theoretical model that assumes piecewise linear dynamics yields partial agreement with the experimental findings

PT-symmetry in honeycomb photonic lattices

We apply gain/loss to honeycomb photonic lattices and show that the dispersion relation is identical to tachyons - particles with imaginary mass that travel faster than the speed of light. This is accompanied by PT-symmetry breaking in this structure. We further show that the PT-symmetry can be restored by deforming the lattice

Exact Z2Z^2 scaling of pair production in the high-energy limit of heavy-ion collisions

The two-center Dirac equation for an electron in the external electromagnetic field of two colliding heavy ions in the limit in which the ions are moving at the speed of light is exactly solved and nonperturbative amplitudes for free electron-positron pair production are obtained. We find the condition for the applicability of this solution for large but finite collision energy, and use it to explain recent experimental results. The observed scaling of positron yields as the square of the projectile and target charges is a result of an exact cancellation of a nonperturbative charge dependence and holds as well for large coupling. Other observables would be sensitive to nonperturbative phases.Comment: 4 pages, Revtex, no figures, submitted to PR

Suppression of geometrical barrier in Bi2Sr2CaCu2O8+δBi_2Sr_2CaCu_2O_{8+\delta} crystals by Josephson vortex stacks

Differential magneto-optics are used to study the effect of dc in-plane magnetic field on hysteretic behavior due to geometrical barriers in $Bi_2Sr_2CaCu_2O_{8+\delta}$ crystals. In absence of in-plane field a vortex dome is visualized in the sample center surrounded by barrier-dominated flux-free regions. With in-plane field, stacks of Josephson vortices form vortex chains which are surprisingly found to protrude out of the dome into the vortex-free regions. The chains are imaged to extend up to the sample edges, thus providing easy channels for vortex entry and for drain of the dome through geometrical barrier, suppressing the magnetic hysteresis. Reduction of the vortex energy due to crossing with Josephson vortices is evaluated to be about two orders of magnitude too small to account for the formation of the protruding chains. We present a model and numerical calculations that qualitatively describe the observed phenomena by taking into account the demagnetization effects in which flux expulsion from the pristine regions results in vortex focusing and in the chain protrusion. Comparative measurements on a sample with narrow etched grooves provide further support to the proposed model.Comment: 12 figures (low res.) Higher resolution figures are available at the Phys Rev B version. Typos correcte

Super-diffusion in optical realizations of Anderson localization

We discuss the dynamics of particles in one dimension in potentials that are random both in space and in time. The results are applied to recent optics experiments on Anderson localization, in which the transverse spreading of a beam is suppressed by random fluctuations in the refractive index. If the refractive index fluctuates along the direction of the paraxial propagation of the beam, the localization is destroyed. We analyze this broken localization, in terms of the spectral decomposition of the potential. When the potential has a discrete spectrum, the spread is controlled by the overlap of Chirikov resonances in phase space. As the number of Fourier components is increased, the resonances merge into a continuum, which is described by a Fokker-Planck equation. We express the diffusion coefficient in terms of the spectral intensity of the potential. For a general class of potentials that are commonly used in optics, the solutions of the Fokker-Planck equation exhibit anomalous diffusion in phase space, implying that when Anderson localization is broken by temporal fluctuations of the potential, the result is transport at a rate similar to a ballistic one or even faster. For a class of potentials which arise in some existing realizations of Anderson localization atypical behavior is found.Comment: 11 pages, 2 figure