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Simulating the properties of many-body fermionic systems is an outstanding computational challenge relevant to material science, quantum chemistry, and particle physics.-5.4pc]Please note that the spelling of the following author names in the manuscript differs from the spelling provided in the article metadata: D. González-Cuadra, D. Bluvstein, M. Kalinowski, R. Kaubruegger, N. Maskara, P. Naldesi, T. V. Zache, A. M. Kaufman, M. D. Lukin, H. Pichler, B. Vermersch, Jun Ye, and P. Zoller. The spelling provided in the manuscript has been retained; please confirm. Although qubit-based quantum computers can potentially tackle this problem more efficiently than classical devices, encoding nonlocal fermionic statistics introduces an overhead in the required resources, limiting their applicability on near-term architectures. In this work, we present a fermionic quantum processor, where fermionic models are locally encoded in a fermionic register and simulated in a hardware-efficient manner using fermionic gates. We consider in particular fermionic atoms in programmable tweezer arrays and develop different protocols to implement nonlocal gates, guaranteeing Fermi statistics at the hardware level. We use this gate set, together with Rydberg-mediated interaction gates, to find efficient circuit decompositions for digital and variational quantum simulation algorithms, illustrated here for molecular energy estimation. Finally, we consider a combined fermion-qubit architecture, where both the motional and internal degrees of freedom of the atoms are harnessed to efficiently implement quantum phase estimation as well as to simulate lattice gauge theory dynamics.

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To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.

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The quantum statistics of atoms is typically observed in the behavior of an ensemble via macroscopic observables. However, quantum statistics modifies the behavior of even two particles. Here, we demonstrate near-complete control over all the internal and external degrees of freedom of two laser-cooled (87)Rb atoms trapped in two optical tweezers. This controllability allows us to observe signatures of indistinguishability via two-particle interference. Our work establishes laser-cooled atoms in optical tweezers as a promising route to bottom-up engineering of scalable, low-entropy quantum systems.

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Understanding the behavior of quantized vortices is essential to gaining insight into diverse superfluid phenomena, from critical-current densities in superconductors to quantum turbulence in superfluids. We observe the real-time dynamics of quantized vortices in trapped dilute-gas Bose-Einstein condensates by repeatedly imaging the vortex cores. The precession frequency of a single vortex is measured by explicitly observing its time dependence and is found to be in good agreement with theory. We further characterize the dynamics of vortex dipoles in two distinct configurations: (i) an asymmetric configuration, in which the vortex trajectories are dynamic and nontrivial, and (ii) a stable, symmetric configuration, in which the dipole is stationary.

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We sought to determine the effect of variation in time-activity budgets (TABs) and foraging behavior on energy expenditure rates of parent black-legged kittiwakes (Rissa tridactyla). We quantified TABs using direct observations of radio-tagged adults and simultaneously measured field metabolic rates (FMR) of these same individuals (n=20) using the doubly labeled water technique. Estimated metabolic rates of kittiwakes attending their brood at the nest or loafing near the colony were similar (ca. 1.3 x basal metabolic rate [BMR]), although loafing during foraging trips was more costly (2.9 x BMR). Metabolic rates during commuting flight (7.3 x BMR) and prey-searching flight (6.2 x BMR) were similar, while metabolic rates during plunge diving were much higher (ca. 47 x BMR). The proportion of the measurement interval spent foraging had a positive effect on FMR (R2=0.68), while the combined proportion of time engaged in nest attendance and loafing near the colony had a negative effect on FMR (R2=0.72). Thus, more than two-thirds of the variation in kittiwake FMR could be explained by the allocation of time among various activities. The high energetic cost of plunge diving relative to straight flight and searching flight suggests that kittiwakes can optimize their foraging strategy under conditions of low food availability by commuting long distances to feed in areas where gross foraging efficiency is high.

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We present the case of two siblings with similar environmental exposure to silica. Both of them developed perinuclear antineutrophil cytoplasmic antibody (p-ANCA)-associated vasculitis with pulmonary-renal syndrome. p-ANCAs were present with antimyeloperoxidase specificity on capture enzyme-linked immunosorbent assay. Treatment with corticosteroids and cyclophosphamide resulted in resolution of the clinical picture. Chronic exposure to silica is the leading environmental factor associated with ANCA-positive vasculitis. Several clusters of systemic vasculitis have been described. Positive and negative human leukocyte antigens (HLA) have been reported in systemic vasculitis. Affected brothers in our case shared one parental HLA haplotype. To the best of our knowledge, this is the first report of a family cluster of silica-induced, ANCA-associated systemic vasculitis with members sharing some of their HLA antigens.

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BACKGROUND/AIM: Recirculation measured by thermodilution includes effects caused by access and cardiopulmonary recirculation. The aims of this study were to illustrate the accuracy of thermodilution in measurement of hemodialysis recirculation and also to identify a sensitive and specific threshold to detect access recirculation. METHODS: 110 studies were performed in 19 patients. Recirculation obtained directly by the blood temperature monitor (BTM) was compared to that calculated from access blood flow, pump blood flow, and cardiac output determined by ultrasound dilution using the hemodialysis monitor (HDM). RESULTS: A highly significant linear correlation was obtained between repeated BTM recirculation measurements (R(BTM, 2) = 0.99.R(BTM, 1) - 0.22%, r(2) = 0.99). There were no significant differences between repeated BTM recirculation measurements with correct placement (11.4+/-7.1 vs. 10.9+/-7.4%, p = NS) or reversed placement (30.0+/-15.6 vs. 30.2 +/-15.9%, p = NS) of blood lines. A strong linear relationship was obtained between the recirculation determined by thermodilution and the recirculation calculated from HDM measurements (R(calc) = 0.98. R(BTM) - 1.49%, r(2) = 0.95). The mean recirculation obtained by BTM was not significantly different from the recirculation calculated by HDM with correct placement (9.5+/- 2.2 vs. 8.6+/-2.5%, p = NS) or with reversed placement (25.4+/-7.8 vs. 23.8+/-7.7%, p = NS) of blood lines. When a recirculation greater than 15% measured by the BTM was considered as the threshold at which true access recirculation occurred, sensitivity and specificity of the thermodilution method to detect access recirculation were 93 and 98%, respectively. CONCLUSIONS: Recirculation measurements made by the BTM are accurate and precise. Even though BTM thermodilution includes effects of cardiopulmonary recirculation, so that low levels of access recirculation might not be detected, a BTM recirculation >15% represents a highly significant access recirculation.

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UNLABELLED: Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis. BACKGROUND: Commonly used bioimpedance analysis (BIA) is insensitive to changes in peritoneal fluid volume. The purpose of this study was to show, to our knowledge for the first time, that a new segmental approach accurately measures extracellular fluid changes during peritoneal dialysis (PD). METHODS: Fourteen stable PD patients were studied during a standard exchange with fluids of known conductivity. Bioimpedance was continuously measured in the arm, trunk, and leg and from wrist to ankle. Volume changes were calculated using both a newly developed sum of segmental BIA (SBIA) and current wrist-to-ankle BIA (WBIA) and were compared with actual volume changes measured gravimetrically. RESULTS: When 2.19 +/- 0.48 L were removed from the peritoneal cavity during draining, 95.2 +/- 13.8% of this volume was detected by SBIA compared with only 12.5 +/- 24. 3% detected by WBIA. When 2.11 +/- 0.20 L of fresh dialysate was infused into the peritoneal cavity during filling, 91.1 +/- 19.6% of this volume was detected by SBIA compared with only 8.8 +/- 21.1% detected by WBIA. CONCLUSION: The good agreement between measured and calculated data using SBIA was due to: (a) improved placement of electrodes, (b) estimation of trunk extracellular volume based on a new algorithm, and (c) consideration of changes in dialysate conductivity. Correct estimation of fluid volume in the trunk is a prerequisite for applications in which direct analysis of fluid changes cannot be performed such as with peritoneal equilibration tests and continuous flow PD.

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Whole body bioimpedance is considered helpful in monitoring the removal of excess body water by ultrafiltration in hemodialysis patients. In this study, the cumulative, estimated decrease in extracellular volume (V(est)) modeled from whole body bioimpedance data was compared with measured volume (Vmeas) removed by ultrafiltration (UFR = 1.01 +/- 0.31 L/hr) in 12 patients during 36 high efficiency hemodialysis treatments. In the mean, estimated (V(est) = 3.0 +/- 1.4 L) and measured volumes (Vmeas = 3.4 +/- 1.1 L) correlated linearly: V(est) = 1.05 x Vmeas - 0.60, r2 = 0.68. Patients developed hypotension in half the treatments. Except for a larger decrease in systolic blood pressures in hypotensive (34 +/- 24 mmHg) vs. stable (14 +/- 15 mmHg) treatments, patient and treatment characteristics were not different between groups. However, at the end of hemodialysis, the difference V(est) - Vmeas was -0.8 +/- 0.9 L in hypotensive, and only 0.1 +/- 0.4 L in stable patients (p < 0.05). The difference between V(est) and Vmeas can be explained by a predominant removal of excess body water from central body compartments such as the trunk and the central blood volume during hypotension. These compartments are not adequately measured by whole body bioimpedance techniques. However, this information could be helpful in identifying patients with delayed peripheral fluid removal that may occur when either target weight is too low or UFR rates are too high.

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Although the use of cooled dialysate during hemodialysis is associated with stabilization of intradialytic BP, the effects of blood cooling on hemodynamics and urea kinetics in high-efficiency hemodialysis have not been completely studied. In particular, the effects of blood cooling have not been elucidated in very short-time, high K/V dialysis treatments, in which postdialysis urea rebound is maximized. In theory, blood cooling could increase urea compartmentalization during treatment and decrease dialysis efficacy. Measurements of cardiovascular hemodynamics and urea kinetics were performed in 15 patients (56 studies) during dialysis, using a blood temperature monitor with control of dialysate temperature. Dialysate temperature was adjusted to either lower the core temperature or raise the core temperature by, respectively, producing negative heat-energy exchange (cooled dialysis) or keeping heat-energy exchange in the extracorporeal circuit neutral (thermoneutral dialysis) so that energy was not transferred to or from the patient. Each subject was studied on both protocols, thereby allowing each individual to act as his own control. In cooled dialysis, heat-energy exchange in the extracorporeal circuit was -266+/-15 kJ per treatment, and dialysate temperature averaged 35.7+/-0.02 degrees C. In thermoneutral dialysis, heat-energy exchange in the extracorporeal circuit averaged 5+/-31 kJ per treatment, and dialysate temperature averaged 37.1+/-0.02 degrees C. Dialysate cooling resulted in a reduction in mean body temperature compared with thermoneutral therapy (-0.22+/-0.04 versus +0.31+/-0.05 degrees C). Cooling resulted in a greater increase in peripheral vascular resistance index (+515+/-160 versus + 114+/-92 dyn.sec/cm5 per m2), an increase in mean arterial pressure (+4+/-3 versus -4+/-4 mmHg), a reduction in the maximum intradialytic fall in mean arterial pressure (-10+/-2 versus -18+/-3, mmHg), and a reduction in staff interventions for hypotension or dialytic symptoms (6 of 28 versus 12 of 28 studies). These differences occurred without differences in the change in blood volume (-14.3+/-1.8% versus -13.9+/-2.2%) or cardiac index (-0.4+/-0.1 versus -0.4+/-0.2, L/min per m2). Urea rebound (37+/-4% versus 38+/-3%) and effective Kt/V (1.29+/-0.05 versus 1.32+/-0.06) were not different between groups. Thus, body temperature cooling can be used to stabilize BP and reduce intradialytic events requiring staff intervention without compromising the efficacy of treatment in high-efficiency dialysis.

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PURPOSE: Recently others advocated frequent radiological surveillance to detect upper urinary tract deterioration in children with neurogenic bladder secondary to spina bifida. We reviewed the consequences of such expectant management on bladder compliance and urinary continence. MATERIALS AND METHODS: We retrospectively reviewed the records of 214 children presenting to our spina bifida clinic in a 13-year period. Follow-up is available for 95 girls and 86 boys. Imaging studies of the kidneys were repeated at 6 to 12-month intervals. Urodynamics were performed when upper urinary tracts deteriorated or in incontinent school age children. RESULTS: On radiographic study there was evidence of upper urinary tract deterioration in 79 children, including hydronephrosis in 34, hydronephrosis and vesicoureteral reflux in 19, and reflux only in 26. Follow up studies performed after clean intermittent catheterization and pharmacological therapy were instituted revealed resolution or improvement of upper tract deterioration in 52 patients (69%), while bladder compliance improved in only 42%. Surgical intervention was required in 34 children, despite improvement of upper tract changes in many of these patients on follow up radiographic studies. CONCLUSIONS: Although radiological surveillance of patients with myelomeningocele allows recognition of upper tract changes, the effects of elevated outlet resistance on bladder compliance are not as readily reversible as the initial radiographic findings. The incidence of enterocystoplasty exceeds that reported for patients treated prospectively based on urodynamic findings, which should be considered in the treatment of these children.

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A major cause of the morbidity and mortality of patients with end-stage renal disease (ESRD) is related to disorders of large blood vessels, especially coronary heart disease. Atherosclerosis, the most common form of this disease, is known to result from abnormalities in plasma lipoproteins, as well as from factors that damage the vessel wall. Two well-known risk factors for coronary heart disease are elevated plasma concentrations of LDL and reduced concentrations of HDL. This latter disorder is often accompanied by elevated triglycerides. Low HDL and elevated triglycerides are commonly associated with ESRD. Dialysis with high flux membranes differs from conventional dialysis in a number of ways. These include better biocompatibility and increased flux of larger molecules. Although several previous studies had suggested that dialysis with high flux membranes improves plasma lipoprotein profiles, a definitive cross-over designed study to assess the roles of high flux versus biocompatibility in altering lipoprotein profiles had not been done. Preliminary data from such a study are presented. These data confirm the beneficial effects of high flux membranes to reduce plasma triglycerides and suggest that this effect is primarily due to the high flux, and not the biocompatible, feature of the membranes.

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Dialyzer reprocessing with heated water (100 to 105 degrees C) for 20 h can be used safely in lieu of chemical methods for disinfection. All infective agents including spores are destroyed and depyrogenation may occur. However, these temperatures may result in structural damage to the dialyzer, limiting reuse. Dialyzer reprocessing by using 1.5% citric acid heated to 95 degrees C for 20 h is an alternative method that produces equivalent microbiologic effects. Citric acid is well known as a disinfecting agent used for dialysis equipment. Because there is little structural damage to dialyzer components at 95 degrees C, reuse statistics are improved (mean reuse increased to 12.8). Both small and large molecule clearances and the sieving coefficient for protein are insignificantly altered by the process. Whereas the procedure is relatively simple, quality-assurance indicators are essential. The method has appeal because it avoids the use of chemical germicides. However, at present it has only been tested thoroughly in polysulfone dialyzers with heat-resistant polycarbonate casings and polyurethane resin. The clinical experience is favorable.

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Mathematical models that simulate the exchange of solute between multiple body compartments have been used to study the distribution, elimination, and transport of urea, water, electrolytes, and other substances in the dialysis patient. Within a compartment, such substances are assumed to be uniformly distributed while exchange between compartments or with the environment may occur in a number of different ways. Diffusion in response to concentration gradients between, for example, intracellular and extracellular spaces, and convection due to blood flow have been identified as the most important transport mechanisms. Any system with more than one compartment may develop nonuniform solute distribution or solute disequilibrium between compartments. The minimum number of compartments required to model a kinetic process such as urea removal during hemodialysis depends on the accuracy and temporal resolution required, with higher resolution calling for more compartments. A two-compartment model is adequate for most clinical purposes. The physiological meaning or anatomic counterparts of the mathematical compartments remain uncertain as both flow and diffusion transport mechanisms contribute to the disequilibrium. Processes such as access and cardiopulmonary recirculation may be represented as additional compartments with small distribution volumes and high mass transport rates. Failure to recognize the effect of multiple compartments will result in an inaccurate measurement of dialysis dose and an inadequate hemodialysis prescription with a predictably poor clinical outcome. Allowance for compartment effects is particularly important in patients receiving treatment with a high ratio of dialyzer clearance to total body water, now commonly encountered during short-time, high-efficiency dialysis.

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In diabetes and ageing, glucose-derived advanced glycosylation endproducts (AGEs) cross-link proteins and cause vascular tissue damage. Elimination of circulating low-molecular weight AGE-modified molecules (LMW-AGEs) by the kidney is impaired in diabetic patients with end-stage renal disease, a group subject to accelerated atherosclerosis. We determined the effectiveness of current renal replacement treatments on elimination of serum LMW-AGEs in diabetic and non-diabetic patients with end-stage renal disease. Although diabetic patients receiving high-flux haemodialysis achieved 33% lower steady-state serum LMW-AGE than did those in conventional haemodialysis (p < 0.005), LMW-AGE concentrations remained 3.5-6 fold above normal, whether high-flux dialysis, conventional haemodialysis, or chronic ambulatory peritoneal dialysis were used. High-flux haemodialysis markedly reduced AGE during each treatment session (47.9% in the diabetic, p < 0.001 and 60.6% in the non-diabetic group, p < 0.001) but concentrations returned to pre-treatment range within 3 hours. In contrast, normal LMW-AGE concentrations were maintained in patients with functioning renal transplants. We found that LMW-AGEs with an apparent molecular weight of 2000-6000 circulate and retain strong inherent chemical reactivity--when exposed to collagen in vitro, up to 77% attached covalently to form AGE-collagen, and the AGE-crosslink inhibitor aminoguanidine completely inhibited this reaction. The results suggest that LMW-AGEs comprise a set of chemically-reactive molecules that are refractory to removal by current dialysis treatments. Through covalent reattachment onto vascular matrix or serum components, LMW-AGEs may exacerbate vascular pathology associated with end-stage renal disease.

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Intradialytic parenteral nutrition (IDPN) therapy is becoming more prevalent in the malnourished patient undergoing maintenance hemodialysis. This is of particular concern to the nephrology nurse in that additional time is required to administer the solution, monitor the patient, and document the process. The IDPN monitoring flowsheet described in this article was developed to promote continuity of care from treatment to treatment, especially during initiation of IDPN, and to assist the nephrology nurse in administering and monitoring the therapy.

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It is generally accepted that morbidity and mortality of hemodialysis patients is related to dialysis quantitation. Currently available methods for the quantitation of dialysis require blood sampling or a continuous measurement of changes in urea concentration during treatment. These maneuvers are time consuming and expensive, and are generally performed, at most, once per month. The authors introduce an on-line, automated method for measurement of dialyzer electrolyte clearance comparable to urea clearance by using dialysate conductivity sensors placed pre and post dialyzer, and measuring conductivity at three different pre dialyzer levels. Conditions that reduce clearance, such as recirculation or fiber clotting, are automatically taken into account so that the method measures effective clearance rather than dialyzer clearance. In vitro and in vivo studies validate the method. Results are immediately available and can be used to address problems such as improper needle placement and access recirculation. In addition, repetitive electrolyte clearance data can serve to enhance quality assurance programs with respect to verifying the function of reused or new dialyzers. Appropriate algorithms can be used to calculate delivered Kt/V.

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