Transition to the Haldane phase driven by electron-electron correlations.

One of the most famous quantum systems with topological properties, the spin [Formula: see text] antiferromagnetic Heisenberg chain, is well-known to display exotic [Formula: see text] edge states. However, this spin model has not been analyzed from the more general perspective of strongly correlated systems varying the electron-electron interaction strength. Here, we report the investigation of the emergence of the Haldane edge in a system of interacting electrons - the two-orbital Hubbard model-with increasing repulsion strength U and Hund interaction JH. We show that interactions not only form the magnetic moments but also form a topologically nontrivial fermionic many-body ground-state with zero-energy edge states. Specifically, upon increasing the strength of the Hubbard repulsion and Hund exchange, we identify a sharp transition point separating topologically trivial and nontrivial ground-states. Surprisingly, such a behaviour appears already at rather small values of the interaction, in a regime where the magnetic moments are barely developed.

Phytoplanktonic community and bio-optical properties in coastal waters of an Argentinian Patagonian gulf.

The influence of the phytoplankton community in the light absorption budget was quantified in coastal waters of the North region of the San Jorge Gulf (Argentinian Patagonia). The phytoplanktonic composition and their absorption spectra were determined. Nanoflagellates and diatoms were the dominant groups. The toxigenic dinoflagellate Dinophysis acuminata was recorded in all the sampling sites. The optical characterization of the particulate material showed that 60 % of the absorption at 443 nm and 88 % of absorption at 675 nm was due to phytoplankton. The contributions of phytoplankton to total absorption at 443 nm wavelengths reached 50 %. The absorption by chromophoric dissolved organic matter (CDOM) and non-algal particles (NAP) was predominant in turbulent waters (>60 %). This study shows the influence of submesoscale physical-biological interactions in the light absorption budget. The field absorption spectra of active optical components are of interest in the assessment and development of regional ocean color satellite algorithms.

Signatures of Dissipation Driven Quantum Phase Transition in Rabi Model.

By using the worldline Monte Carlo technique, matrix product state, and a variational approach à la Feynman, we investigate the equilibrium properties and relaxation features of the dissipative quantum Rabi model, where a two level system is coupled to a linear harmonic oscillator embedded in a viscous fluid. We show that, in the Ohmic regime, a Beretzinski-Kosterlitz-Thouless quantum phase transition occurs by varying the coupling strength between the two level system and the oscillator. This is a nonperturbative result, occurring even for extremely low dissipation magnitude. By using state-of-the-art theoretical methods, we unveil the features of the relaxation towards the thermodynamic equilibrium, pointing out the signatures of quantum phase transition both in the time and frequency domains. We prove that, for low and moderate values of the dissipation, the quantum phase transition occurs in the deep strong coupling regime. We propose to realize this model by coupling a flux qubit and a damped LC oscillator.

Trocar vs. Seldinger small bore pleural drains: does the technique influence the outcomes? A prospective single-centre study.

OBJECTIVE: The aim of this study is to compare two positioning techniques of 12-French (Fr) thoracic drains in terms of efficacy, safety, and patient comfort. PATIENTS AND METHODS: This is a prospective, non-randomized, competitive, non-inferiority study comparing the Seldinger vs. Trocar technique. The primary endpoint was an analysis of the factors that led to unsuccessful drainage positioning. Between the two groups, clinical variables, procedure times, pain, and complications were compared. RESULTS: Seventy-two patients were enrolled in group 1 (Seldinger) and 45 in group 2 (Trocar). The mean procedural time was 7.93±3.02 min vs. 7.09±3.67 min, respectively (p: 0.33). The mean VAS for procedural pain was 2.22±1.47 vs. 2.80±1.88, p: 0.07, and the mean at day 2 was 3.6±1.2 in the SBWGD group vs. 2.7±1.1 in the Unico Group (p: 0.04). There was no difference in terms of complications, residual effusion, and pneumothorax at the first post-procedural chest X-ray. Four days after the procedure, the drain removal rate was 11.6% in group 1 vs. 25% in group 2 p: 0.063). The chest tube was removed after a mean period of 8.87±7.20 days after resolution of pleural effusion or tube dislodgement (7 cases in group 1 vs. 11 in group 2, p: 0.053). CONCLUSIONS: The two techniques resulted in comparable pain and complication rates. Both drains are well-tolerated and efficient at draining pleural effusion, with very low rates of complications and failure. We recommend inserting a longer tube for patients who require chest drainage for an extended period of time.

Quadrupolar magnetic excitations in an isotropic spin-1 antiferromagnet.

The microscopic origins of emergent behaviours in condensed matter systems are encoded in their excitations. In ordinary magnetic materials, single spin-flips give rise to collective dipolar magnetic excitations called magnons. Likewise, multiple spin-flips can give rise to multipolar magnetic excitations in magnetic materials with spin S ≥ 1. Unfortunately, since most experimental probes are governed by dipolar selection rules, collective multipolar excitations have generally remained elusive. For instance, only dipolar magnetic excitations have been observed in isotropic S = 1 Haldane spin systems. Here, we unveil a hidden quadrupolar constituent of the spin dynamics in antiferromagnetic S = 1 Haldane chain material Y2BaNiO5 using Ni L3-edge resonant inelastic x-ray scattering. Our results demonstrate that pure quadrupolar magnetic excitations can be probed without direct interactions with dipolar excitations or anisotropic perturbations. Originating from on-site double spin-flip processes, the quadrupolar magnetic excitations in Y2BaNiO5 show a remarkable dual nature of collective dispersion. While one component propagates as non-interacting entities, the other behaves as a bound quadrupolar magnetic wave. This result highlights the rich and largely unexplored physics of higher-order magnetic excitations.

P-glycoprotein inhibition with verapamil overcomes mometasone resistance in Chronic Sinusitis with Nasal Polyps.

BACKGROUND: P-glycoprotein (P-gp) is a membrane efflux pump which is overexpressed in Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) and promotes Type 2 inflammation. Glucocorticoids (GC) are substrates of P-gp suggesting that overexpression may additionally contribute to GC resistance in CRSwNP. This study aims to determine whether P-gp inhibition using verapamil enhances mometasone retention and efficacy in nasal polyp explants. METHODOLOGY: IRB approved study in which organotypic polyp explants were exposed to mometasone (4.15 µg/mL) and verapa- mil (125 µg/mL) as mono and combination therapy. The effect of verapamil on mometasone tissue retention over time was deter- mined using HPLC. The effect of verapamil on mometasone anti-inflammatory function was determined using ELISA for secreted IL-5. Groups were compared using Kruskal-Wallis test. RESULTS: P-gp expression strongly and significantly inversely correlated with mometasone retention 1hr after exposure, with a ne- arly 6-fold reduction in tissue retention between the lowest and highest P-gp expressing polyp explants. P-gp inhibition reversed this effect and significantly improved mometasone retention at 1hr relative to mometasone alone. The combination of mome- tasone and verapamil significantly reduced IL-5 secretion relative to vehicle control and outperformed either treatment alone. CONCLUSIONS: Our study confirms that P-gp contributes to mometasone resistance. This P-gp mediated resistance was successfully reversed by addition of the P-gp inhibitor verapamil. Verapamil further significantly enhanced the anti-inflammatory effect of mometasone when given as a combination therapy.

Spin dynamics of the block orbital-selective Mott phase.

Iron-based superconductors display a variety of magnetic phases originating in the competition between electronic, orbital, and spin degrees of freedom. Previous theoretical investigations of the multi-orbital Hubbard model in one-dimension revealed the existence of an orbital-selective Mott phase (OSMP) with block spin order. Recent inelastic neutron scattering (INS) experiments on the BaFe2Se3 ladder compound confirmed the relevance of the block-OSMP. Moreover, the powder INS spectrum revealed an unexpected structure, containing both low-energy acoustic and high-energy optical modes. Here we present the theoretical prediction for the dynamical spin structure factor within a block-OSMP regime using the density-matrix renormalization-group method. In agreement with experiments, we find two dominant features: low-energy dispersive and high-energy dispersionless modes. We argue that the former represents the spin-wave-like dynamics of the block ferromagnetic islands, while the latter is attributed to a novel type of local on-site spin excitations controlled by the Hund coupling.

Computing Resonant Inelastic X-Ray Scattering Spectra Using The Density Matrix Renormalization Group Method.

We present a method for computing the resonant inelastic x-ray scattering (RIXS) spectra in one-dimensional systems using the density matrix renormalization group (DMRG) method. By using DMRG to address this problem, we shift the computational bottleneck from the memory requirements associated with exact diagonalization (ED) calculations to the computational time associated with the DMRG algorithm. This approach is then used to obtain RIXS spectra on cluster sizes well beyond state-of-the-art ED techniques. Using this new procedure, we compute the low-energy magnetic excitations observed in Cu L-edge RIXS for the challenging corner shared CuO4 chains, both for large multi-orbital clusters and downfolded t-J chains. We are able to directly compare results obtained from both models defined in clusters with identical momentum resolution. In the strong coupling limit, we find that the downfolded t-J model captures the main features of the magnetic excitations probed by RIXS only after a uniform scaling of the spectra is made.

Kidney Intragraft Homing of De Novo Donor-Specific HLA Antibodies Is an Essential Step of Antibody-Mediated Damage but Not Per Se Predictive of Graft Loss.

Donor-specific HLA antibody (DSA)-mediated graft injury is the major cause of kidney loss. Among DSA characteristics, graft homing has been suggested as an indicator of severe tissue damage. We analyzed the role of de novo DSA (dnDSA) graft homing on kidney transplantation outcome. Graft biopsy specimens and parallel sera from 48 nonsensitized pediatric kidney recipients were analyzed. Serum samples and eluates from graft biopsy specimens were tested for the presence of dnDSAs with flow bead technology. Intragraft dnDSAs (gDSAs) were never detected in the absence of serum dnDSAs (sDSAs), whereas in the presence of sDSAs, gDSAs were demonstrated in 72% of biopsy specimens. A significantly higher homing capability was expressed by class II sDSAs endowed with high mean fluorescence intensity and C3d- and/or C1q-fixing properties. In patients with available sequential biopsy specimens, we detected gDSAs before the appearance of antibody-mediated rejection. In sDSA-positive patients, gDSA positivity did not allow stratification for antibody-mediated graft lesions and graft loss. However, a consistent detection of skewed unique DSA specificities was observed over time within the graft, likely responsible for the damage. Our results indicate that gDSAs could represent an instrumental tool to identify, among sDSAs, clinically relevant antibody specificities requiring monitoring and possibly guiding patient management.

Spectral functions with the density matrix renormalization group: Krylov-space approach for correction vectors.

Frequency-dependent correlations, such as the spectral function and the dynamical structure factor, help illustrate condensed matter experiments. Within the density matrix renormalization group (DMRG) framework, an accurate method for calculating spectral functions directly in frequency is the correction-vector method. The correction vector can be computed by solving a linear equation or by minimizing a functional. This paper proposes an alternative to calculate the correction vector: to use the Krylov-space approach. This paper then studies the accuracy and performance of the Krylov-space approach, when applied to the Heisenberg, the t-J, and the Hubbard models. The cases studied indicate that the Krylov-space approach can be more accurate and efficient than the conjugate gradient, and that the error of the former integrates best when a Krylov-space decomposition is also used for ground state DMRG.

Acquisition of C3d-Binding Activity by De Novo Donor-Specific HLA Antibodies Correlates With Graft Loss in Nonsensitized Pediatric Kidney Recipients.

Alloantibody-mediated graft injury is a major cause of kidney dysfunction and loss. The complement-binding ability of de novo donor-specific antibodies (dnDSAs) has been suggested as a prognostic tool to stratify patients for clinical risk. In this study, we analyzed posttransplant kinetics of complement-fixing dnDSAs and their role in antibody-mediated rejection development and graft loss. A total of 114 pediatric nonsensitized recipients of first kidney allograft were periodically monitored for dnDSAs using flow bead assays, followed by C3d and C1q assay in case of positivity. Overall, 39 patients developed dnDSAs, which were C1q(+) and C3d(+) in 25 and nine patients, respectively. At follow-up, progressive acquisition over time of dnDSA C1q and C3d binding ability, within the same antigenic specificity, was observed, paralleled by an increase in mean fluorescence intensity that correlated with clinical outcome. C3d-fixing dnDSAs were better fit to stratify graft loss risk when the different dnDSA categories were evaluated in combined models because the 10-year graft survival probability was lower in patients with C3d-binding dnDSA than in those without dnDSAs or with C1q(+) /C3d(-) or non-complement-binding dnDSAs (40% vs. 94%, 100%, and 100%, respectively). Based on the kinetics profile, we favor dnDSA removal or modulation at first confirmed positivity, with treatment intensification guided by dnDSA biological characteristics.

Noise-assisted charge pump in elastically deformable molecular junctions.

We study a charge pump realized with an elastically deformable quantum dot whose center of mass follows a nonlinear stochastic dynamics. The interplay of noise, nonlinear effects, dissipation and interaction with an external time-dependent driving on the pumped charge is fully analyzed. The results show that the quantum pumping mechanism not only is not destroyed by the force fluctuations, but it becomes stronger when the forcing signal frequency is tuned close to the resonance of the vibrational mode. The robustness of the quantum pump with temperature is also investigated and an exponential decay of the pumped charge is found when the coupling to the vibrational mode is present. Implications of our results for nanoelectromechanical systems are also discussed.

Posttransplant de novo donor-specific hla antibodies identify pediatric kidney recipients at risk for late antibody-mediated rejection.

The emerging role of humoral immunity in the pathogenesis of chronic allograft damage has prompted research aimed at assessing the role of anti-HLA antibody (Ab) monitoring as a tool to predict allograft outcome. Data on the natural history of allografts in children developing de novo Ab after transplantation are limited. Utilizing sera collected pretransplant, and serially posttransplant, we retrospectively evaluated 82 consecutive primary pediatric kidney recipients, without pretransplant donor-specific antibodies (DSA), for de novo Ab occurrence, and compared results with clinical-pathologic data. At 4.3-year follow up, 19 patients (23%) developed de novo DSA whereas 24 had de novo non-DSA (NDSA, 29%). DSA appeared at a median time of 24 months after transplantation and were mostly directed to HLA-DQ antigens. Among the 82 patients, eight developed late/chronic active C4d+ antibody-mediated rejection (AMR), and four C4d-negative AMR. Late AMR correlated with DSA (p < 0.01), whose development preceded AMR by 1-year median time. Patients with DSA had a median serum creatinine of 1.44 mg/dL at follow up, significantly higher than NDSA and Ab-negative patients (p < 0.005). In our pediatric cohort, DSA identify patients at risk of renal dysfunction, AMR and graft loss; treatment started at Ab emergence might prevent AMR occurrence and/or progression to graft failure.

Kidney transplantation from living donors genetically related or unrelated to the recipients: a single-center analysis.

Living-donor programs have gradually become an attractive strategy to expand the donor pool for kidney transplantation (KT). Grafts from living-related donors (LRD) display superior function and longer survival than those obtained from cadaveric sources. Recent reports have shown that outcomes from living-unrelated donors (LUD) are not worse than those from LRD. In this study, we evaluated 135 procedures using living donors performed in our center between 1987 and 2010 (LRD: n = 111; LUD: n = 24). Among the LRD, most donors were mothers (n = 61; 54.95%), fathers (n = 25; 22.52%), and sisters (n = 16; 14.41%). The LUD included wives (n = 17; 70.83%) and husbands (n = 7; 29.17%). The mean recipient ages for LRD versus LUD were 26.94 ± 13.51 and 50.04 ± 8.86 years, respectively (P < .0001). The recipient female/male distribution was 33/78 (29.73%/70.27%) for the LRD versus 6/18 (25%/75%) for the LUD group (P = .643). The donor age was 48.79 ± 9 years in LRD and 49.25 ± 8.44 years in LUD (P = .696). The donor female/male distribution was 72/39 (64.86%/35.16%) in LRD and 17/7 (70.83%/29.17%) in LUD (P = .576). The follow up was 123.79 ± 87.87 months (range, 0.91-279.93). Overall patient and graft survivals were 94.1% and 67.6%, respectively. There was no significant difference in patient survival after stratifying for donor type (LRD: 93.9%; LUD: 95.8%; P = .961) or in graft survival after stratifying for donor type (LRD: 63.8%; LUD: 87.8%; P = .124). Entering donor type as an independent variable in a univariate Cox regression, we observed no significance for either recipient (P = .961) or graft survival (P = .142). The results of this study suggest that LUD utilization should be encouraged in KT programs.

A single-center analysis to evaluate kidney function parameters after liver transplantation in adult patients.

Severe renal dysfunction may occur after orthotopic liver transplantation (OLT). In this study, we retrospectively analyzed a single-center series of adult liver recipients (n = 62) seeking to identify patients prone to develop renal dysfunction during follow-up. Liver recipients (age range, 53.54 ± 8.19 years; female/male: 21/41) who underwent a first OLT from a brain dead donor were enrolled according to strict criteria. We enrolled only liver recipients with 5 serum creatinine (SCr) measurements after hospital discharge and at least 1 measurement/year with a follow-up period of not less than 2 years. We estimated glomerular filtration rate (eGFR) using the formula developed by the Mayo Clinic. The average rate of SCr change after OLT was 0.0065 ± 0.013 mg/dL/mo. By calculating the per-patient slope, the average rate of SCr change was 0.000165 ± 0.000383 mg/dL (0.000007 ± 0.000017 mg/dL/mo). In regression models evaluated with SCr as the dependent variable versus post-OLT time, no significance was observed (P = .130). The average rate of eGFR change after OLT was -0.462 ± 0.883 mL/min/mo. By calculating the per-patient slope, the average rate of eGFR change was -0.009 ± 0.0026 mL/min (-0.0004 ± 0.0012 mL/min/mo). In the regression models evaluated with eGFR as dependent variable versus post-OLT time, no significance occurred (P = .168). By applying the regression prediction to SCr at 3 to 5 versus the 1 to 2 post-OLT measurements, we noted 3 male liver recipients (MLR) whose SCr values were significantly higher than the predicted values: MLR1: P = .048 at measurement 4; MLR2: P = .019 at measurement 4; and MLR3: P = .017 at measurement 5. Conversely, we did not observed a significant difference between observed versus predicted eGFR values. Clinical decisions on immunosuppressive treatments for liver recipients should be determined also on the basis of the series of post-OLT kidney function, which should be studied with rigorous evaluation of fitted regression models.

Regulatory functions of insulin-like growth factor binding proteins in osteoarthritis.

Insulin-like growth factor binding proteins (IGFBPs) are a group of secreted proteins, which bind to IGF-I (and IGF-II) with high affinity and modulate the biological actions of IGFs. Abundant evidence points the importance of the IGF-I/IGFBP system on both cell growth and differentiation. A role for the IGF-I/IGFBP system in the regulation of normal human cartilage has been previously reported. In this context, recent studies suggest an emerging role for IGFBPs in the failure of cartilage during osteoarthritis (OA). Indeed, increased IGFBP levels have been reported in both the articular cartilage and synovial fluid from patients with OA. Overexpression of IGFBPs, by altering the bioavailability and function of IGFs, is likely to deliver IGFs-independent signals for chondrocyte survival. This, at least in part, might explain the degenerative changes of the cartilage in OA. Further studies are necessary to clarify the mechanisms that cause the overexpression of IGFBPs in patients with OA. Advances in our understanding of the relationship between osteoarthritis and the IGF-I/IGFBP system may lead to new treatment strategies for this degenerative disease.

Application and validation of Cox regression models in a single-center series of double kidney transplantation.

A useful approach to reduce the number of discarded marginal kidneys and to increase the nephron mass is double kidney transplantation (DKT). In this study, we retrospectively evaluated the potential predictors for patient and graft survival in a single-center series of 59 DKT procedures performed between April 21, 1999, and September 21, 2008. The kidney recipients of mean age 63.27 +/- 5.17 years included 16 women (27%) and 43 men (73%). The donors of mean age 69.54 +/- 7.48 years included 32 women (54%) and 27 men (46%). The mean posttransplant dialysis time was 2.37 +/- 3.61 days. The mean hospitalization was 20.12 +/- 13.65 days. Average serum creatinine (SCr) at discharge was 1.5 +/- 0.59 mg/dL. In view of the limited numbers of recipient deaths (n = 4) and graft losses (n = 8) that occurred in our series, the proportional hazards assumption for each Cox regression model with P < .05 was tested by using correlation coefficients between transformed survival times and scaled Schoenfeld residuals, and checked with smoothed plots of Schoenfeld residuals. For patient survival, the variables that reached statistical significance were donor SCr (P = .007), donor creatinine cleararance (P = .023), and recipient age (P = .047). Each significant model passed the Schoenfeld test. By entering these variables into a multivariate Cox model for patient survival, no further significance was observed. In the univariate Cox models performed for graft survival, statistical significance was noted for donor SCr (P = .027), SCr 3 months post-DKT (P = .043), and SCr 6 months post-DKT (P = .017). All significant univariate models for graft survival passed the Schoenfeld test. A final multivariate model retained SCr at 6 months (beta = 1.746, P = .042) and donor SCr (beta = .767, P = .090). In our analysis, SCr at 6 months seemed to emerge from both univariate and multivariate Cox models as a potential predictor of graft survival among DKT. Multicenter studies with larger recipient populations and more graft losses should be performed to confirm our findings.

Long-term outcome on kidney retransplantation: a review of 100 cases from a single center.

Renal transplantation has become an effective form of treatment for end-stage renal failure. Unfortunately, as a consequence of immunological and nonimmunological pathogenic mechanisms, chronic allograft nephropathy is responsible for the loss of a large proportion of kidney grafts after several years and return to dialysis. We have reported herein our 24 years of experience with second kidney transplantations. Of 1,302 kidney transplantations between January 1983 and June 2007 performed in our transplantation center, 100 were second transplantations. Kidney retransplantation was performed in 74 men and 26 women of overall mean age of 35.4 +/- 12.6 years. Cadaveric donor grafts were transplanted in 92 patients, whereas the remaining 8 were living-related donor kidneys. At 1, 5, and 10 years after kidney transplantation, patient survival rates were 100%, 96%, and 92%, respectively, whereas graft survival rates were 85%, 72%, and 53%, respectively. Immunosuppressive therapy included induction therapy with polyclonal anti-lymphocyte antibodies (ALG/ATG) or (starting from 1999) monoclonal anti CD 25 antibody. Our results demonstrated good outcomes for kidney retransplantations with allocation based on anti- HLA antibody identification together with induction immunosuppression.

Sirolimus therapy in liver transplant patients: an initial experience at a single center.

Sirolimus (SRL) is an mTOR inhibitor that has been shown, in contrast to calcineurin inhibitors (CNI), to inhibit cancers in experimental models. Since February 2005, we introduced SRL in liver transplant patients in group a, in whom the primary disease was hepatocellular carcinoma (HCC) associated with hepatitis B virus (HBV), hepatitis C virus (HCV), alcoholic or autoimmune liver cirrhosis, and group b, HCC-negative patients who developed posttransplantation cancers de novo. Of 18 patients in group a, 11 received SRL ab initio (subgroup a1), starting for 10 patients at 66.1+/-29.2 days after surgical healing and after 10 days in 1 case; the remaining 7 patients (subgroup a2) received SRL at 31.2+/-24.2 months. Three patients in group b, included 1 with Kaposi's sarcoma, 1 with bladder cancer, and 1 with thyroid cancer. In this group, SRL was introduced at 80.8+/-40.4 months. In all patients but one, who received a single 5 mg loading dose, SRL was started at 2 mg/d and adjusted to 6 to 8 ng/mL blood levels. CNI drugs, present as primary therapy, were gradually tapered to low levels and eventually stopped. The following observations were drawn from this initial experience: (1) 4/21 (19.0%) patients had to discontinue SRL because of early and late side effects: thrombocytopenia (n=2) and headache with leukopenia and leg edema associated with knee joint arthralgia (n=2); (2) 14 patients (11 in group a and 3 in group b) are still on SRL monotherapy; (3) 1 HCC recurrence and 1 de novo pancreatic adenocarcinoma were observed at 14 and 16 months, respectively (at the time of transplantation, both patients were beyond the MIlan HCC criteria), and (4) 1 patient, from subgroup a1, died after 99 days due to pneumonitis and possible relation to SRL lung toxicity. In conclusion, SRL appeared to be an effective immunosuppressant that could be used as monotherapy in liver transplant patients. Any conclusion on SRL anticancer effects can only come from randomized large studies after long follow-up.