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Oliver Masur, Martin Schütz, Lorenzo Maschio, Denis Usvyat
We present a periodic/finite-cluster interface for fragment-based direct local ring-coupled-cluster doubles (d-LrCCD) calculations embedded in the periodic mean field. The fragment is defined by a set of Wannier functions (WFs), obtained from a periodic Hartree-Fock calculation. The pair-specific virtual space is spanned by projected atomic orbitals (PAOs) truncated to pair domains. The computational procedure is initiated by a periodic local Møller-Plesset (LMP2) calculation. A subset of the WF pairs is then subsequently subjected to a finite-cluster d-LrCCD treatment using the local coupled cluster program of Molpro; this subset is specified by an interorbital cutoff distance...
October 11, 2016: Journal of Chemical Theory and Computation
M J E Dekker, D Marcelli, B Canaud, C J A M Konings, K M Leunissen, N W Levin, P Carioni, V Maheshwari, J G Raimann, F M van der Sande, L A Usvyat, P Kotanko, J P Kooman
BACKGROUND/OBJECTIVES: Hyponatremia is a risk factor for mortality in hemodialysis (HD) patients. It is not well known to which extent the comorbidities, malnutrition, fluid status imbalance and inflammation are related to hyponatremia and affect outcomes. SUBJECTS/METHODS: We studied 8883 patients from the European subset of the international MONitoring Dialysis Outcomes initiative. Nutritional and fluid statuses were assessed by bioimpedance spectroscopy. Fluid depletion was defined as overhydration⩽-1...
July 2016: European Journal of Clinical Nutrition
Maria Ferris, Keisha Gibson, Brett Plattner, Debbie S Gipson, Peter Kotanko, Daniele Marcelli, Cristina Marelli, Michael Etter, Paola Carioni, Gero von Gersdorff, Xiaoqi Xu, Jeroen P Kooman, Qingqing Xiao, Frank M van der Sande, Albert Power, Roberto Picoits-Filho, Lucimary Sylvestre, Katherine Westreich, Len Usvyat
BACKGROUND: The aim of this study was to describe the experience of pediatric and young adult hemodialysis (HD) patients from a global cohort. METHODS: The Pediatric Investigation and Close Collaborative Consortium for Ongoing Life Outcomes for MONitoring Dialysis Outcomes (PICCOLO MONDO) study provided de-identified electronic information of 3244 patients, ages 0-30 years from 2000 to 2012 in four regions: Asia, Europe, North America and South America. The study sample was categorized into pediatric (≤18 years old) and young adult (19-30 years old) groups based on the age at dialysis initiation...
April 2016: Clinical Kidney Journal
Andreja Marn Pernat, Vanja Peršič, Len Usvyat, Lynn Saunders, John Rogus, Franklin W Maddux, Eduardo Lacson, Peter Kotanko
OBJECTIVE: Patients with diabetes are at increased risk of foot ulcers, which may result in limb amputations. While regular foot care prevents ulcerations and amputation in those patients with diabetes not on dialysis, evidence is limited in diabetic hemodialysis patients. We investigated the association between the implementation of a routine foot check program in diabetic incident hemodialysis patients, and major lower limb amputations. METHODS: In 1/2008, monthly intradialytic foot checks were implemented as part of standard clinic care in all Fresenius Medical Care North America hemodialysis facilities...
2016: BMJ Open Diabetes Research & Care
Gero Wälz, Denis Usvyat, Tatiana Korona, Martin Schütz
We present a hierarchy of local coupled cluster (CC) linear response (LR) methods to calculate ionization potentials (IPs), i.e., excited states with one electron annihilated relative to a ground state reference. The time-dependent perturbation operator V(t), as well as the operators related to the first-order (with respect to V(t)) amplitudes and multipliers, thus are not number conserving and have half-integer particle rank m. Apart from calculating IPs of neutral molecules, the method offers also the possibility to study ground and excited states of neutral radicals as ionized states of closed-shell anions...
February 28, 2016: Journal of Chemical Physics
Dugan W Maddux, Len A Usvyat, Daniel DeFalco, Peter Kotanko, Jeroen P Kooman, Frank M van der Sande, Franklin W Maddux
BACKGROUND: Pre-dialysis chronic kidney disease (CKD) care impacts dialysis start and incident dialysis outcomes. We describe the use of late stage CKD population data coupled with CKD case management to improve dialysis start. METHODS: The Renal Care Coordinator (RCC) program is a nephrology practice and Fresenius Medical Care North America (FMCNA) partnership involving a case manager resource and data analytics. We studied patients starting dialysis between August 1, 2009 and February 28, 2013 in 9 nephrology practices partnering in the RCC program...
March 2016: Clinical Nephrology
Giuseppe Sansone, Lorenzo Maschio, Denis Usvyat, Martin Schütz, Antti Karttunen
The black phosphorus (black-P) crystal is formed of covalently bound layers of phosphorene stacked together by weak van der Waals interactions. An experimental measurement of the exfoliation energy of black-P is not available presently, making theoretical studies the most important source of information for the optimization of phosphorene production. Here, we provide an accurate estimate of the exfoliation energy of black-P on the basis of multilevel quantum chemical calculations, which include the periodic local Møller-Plesset perturbation theory of second order, augmented by higher-order corrections, which are evaluated with finite clusters mimicking the crystal...
January 7, 2016: Journal of Physical Chemistry Letters
Carsten Müller, Denis Usvyat
A method for accurate calculations of the cohesive energy of molecular crystals is presented. The cohesive energy is evaluated as a sum of several components. The major contribution is captured by periodic Hartree-Fock (HF) coupled with the local Møller-Plesset perturbation theory of second order (LMP2) with a triple-ζ basis set. Post-MP2 corrections and corrections for the basis set incompleteness are calculated from inexpensive incremental calculations with finite clusters. This is an essential improvement with respect to the periodic LMP2 method and allows for results of benchmark quality for crystalline systems...
December 10, 2013: Journal of Chemical Theory and Computation
Denis Usvyat
A multilevel hierarchical ab initio protocol for calculating adsorption on non-conducting surfaces is presented. It employs fully periodic treatment, which reaches local Møller-Plesset perturbation theory of second order (MP2) with correction for the basis set incompleteness via the local F12 technique. Post-MP2 corrections are calculated using finite clusters. That includes the coupled cluster treatment in the local and canonical frameworks (up to perturbative quadruples) and correlated core (with MP2). Using this protocol, the potential surface of hydrogen molecules adsorbed on graphane was computed...
September 14, 2015: Journal of Chemical Physics
Giuseppe Sansone, Bartolomeo Civalleri, Denis Usvyat, Julien Toulouse, Kamal Sharkas, Lorenzo Maschio
Quantum chemistry methods exploiting density-functional approximations for short-range electron-electron interactions and second-order Møller-Plesset (MP2) perturbation theory for long-range electron-electron interactions have been implemented for periodic systems using Gaussian-type basis functions and the local correlation framework. The performance of these range-separated double hybrids has been benchmarked on a significant set of systems including rare-gas, molecular, ionic, and covalent crystals. The use of spin-component-scaled MP2 for the long-range part has been tested as well...
September 14, 2015: Journal of Chemical Physics
Denis Usvyat, Lorenzo Maschio, Martin Schütz
We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy...
September 14, 2015: Journal of Chemical Physics
Adrian M Guinsburg, Len A Usvyat, Michael Etter, Xiaoqi Xu, Stephan Thijssen, Daniele Marcelli, Bernard Canaud, Cristina Marelli, Claudia Barth, Yuedong Wang, Paola Carioni, Frank M van der Sande, Peter Kotanko, Jeroen P Kooman
BACKGROUND: Seasonal mortality differences have been reported in US hemodialysis (HD) patients. Here we examine the effect of seasons on mortality, clinical and laboratory parameters on a global scale. METHODS: Databases from the international Monitoring Dialysis Outcomes (MONDO) consortium were queried to identify patients who received in-center HD for at least 1 year. Clinics were stratified by hemisphere and climate zone (tropical or temperate). We recorded mortality and computed averages of pre-dialysis systolic blood pressure (pre-SBP), interdialytic weight gain (IDWG), serum albumin, and log C-reactive protein (CRP)...
2015: BMC Nephrology
J G Raimann, B Canaud, M Etter, J P Kooman, N W Levin, D Marcelli, C Marelli, A Power, N Duncan, F M van der Sande, P Carioni, S Thijssen, X Xu, L A Usvyat, Y Wang, P Kotanko
A recent study from the United Kingdom indicates an association between pre hemodialysis (HD) serum sodium (SNa(+)) and systolic and diastolic blood pressure (SBP and DBP) in chronic HD patients. We extend this analysis to an international cohort of incident HD patients. The Monitoring Dialysis Outcomes initiative encompasses patients from 41 countries. Over 2 years monthly pre-HD SNa(+) levels were used as predictors of pre-HD SBP and DBP in a linear mixed model (LMM) adjusted for age, gender, interdialytic weight gain, diabetes, serum albumin and calcium...
July 2016: Journal of Human Hypertension
Stephan Thijssen, Michelle M Y Wong, Len A Usvyat, Qingqing Xiao, Peter Kotanko, Franklin W Maddux
BACKGROUND AND OBJECTIVES: Dialysis patients have a high risk for inadequate nutrition. Their nutritional status is particularly susceptible to deterioration when faced with intercurrent events such as hospitalization. This study was conducted to improve the understanding of the temporal evolution of nutritional parameters as a foundation for rational and proactive nutritional intervention. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A retrospective cohort study was performed to investigate the temporal evolution of nutritional parameters (serum albumin, serum phosphate, serum creatinine, equilibrated normalized protein catabolic rate, and interdialytic weight gain) and a composite nutritional score derived from these parameters, in two populations: (1) incident hemodialysis (HD) patients who started HD between January 2006 and December 2011 and were followed for up to 54 months (median 16...
September 4, 2015: Clinical Journal of the American Society of Nephrology: CJASN
Rakesh Malhotra, Daniele Marcelli, Gero von Gersdorff, Aileen Grassmann, Mathias Schaller, Inga Bayh, Laura Scatizzi, Michael Etter, Adrian Guinsburg, Claudia Barth, Cristina Marelli, Paola Carioni, Frank van der Sande, Jeroen P Kooman, Eric Liu, Ted Toffelmire, Yuedong Wang, Stephan Thijssen, Len A Usvyat, Peter Kotanko
BACKGROUND/AIM: The neutrophil-to-lymphocyte ratio (NLR), defined as the neutrophil count divided by lymphocyte count, is an inexpensive and readily available parameter, which may serve as a surrogate for inflammation markers, such as C-reactive protein (CRP). The aim of this study was to determine the utility of NLR in the prediction of elevated CRP levels in hemodialysis (HD) patients. METHODS: We analyzed 43,272 HD patients from 2 distinct cohorts within the Monitoring Dialysis Outcomes research collaboration in whom contemporaneous measurements of neutrophil and lymphocyte counts, serum albumin and CRP levels were available...
2015: Nephron
Natascha J H Broers, Len A Usvyat, Jeroen P Kooman, Frank M van der Sande, Eduardo Lacson, Peter Kotanko, Franklin W Maddux
BACKGROUND/AIM: Physical component summary (PCS) and mental component summary (MCS) scores are associated with hospitalization and mortality in patients with end-stage renal disease. Most studies in these patients are cross-sectional in nature. This study aimed to assess the dynamics of health-related quality of life (HRQOL) over time, as well as determinants of changes in HRQOL. Also, the relation between changes in HRQOL with respect to both hospitalization and mortality was assessed...
2015: Nephron
Paul Balter, Linda H Ficociello, Patrice B Taylor, Len Usvyat, Dixie-Ann Sawin, Claudy Mullon, Jose Diaz-Buxo, Paul Zabetakis
BACKGROUND: Inadequate removal of extracellular volume markedly increases blood pressure and contributes to high morbidity and mortality in hemodialysis patients. Advances in fluid management are needed to improve clinical outcomes. The aim of this quality improvement project was to examine the advantages of using a hematocrit-based, blood volume monitor (Crit-Line * ) for 12 months, as part of a clinic-wide, fluid management program in one dialysis facility. METHODS: Forty-five individuals were receiving hemodialysis at one facility at project initiation and are included in this analysis...
2015: Current Medical Research and Opinion
Daniele Marcelli, Len A Usvyat, Peter Kotanko, Inga Bayh, Bernard Canaud, Michael Etter, Emanuele Gatti, Aileen Grassmann, Yuedong Wang, Cristina Marelli, Laura Scatizzi, Andrea Stopper, Frank M van der Sande, Jeroen Kooman
BACKGROUND AND OBJECTIVES: High body mass index appears protective in hemodialysis patients, but uncertainty prevails regarding which components of body composition, fat or lean body mass, are primarily associated with survival. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Data between April 2006 and December 2012 were extracted from the Fresenius Medical Care Europe subset of the international MONitoring Dialysis Outcomes initiative. Fresenius Medical Care Europe archives a unique repository of predialysis body composition measurements determined by multifrequency bioimpedance (BCM Body Composition Monitor)...
July 7, 2015: Clinical Journal of the American Society of Nephrology: CJASN
Max Schwilk, Denis Usvyat, Hans-Joachim Werner
In local coupled cluster treatments the electron pairs can be classified according to the magnitude of their energy contributions or distances into strong, close, weak, and distant pairs. Different approximations are introduced for the latter three classes. In this communication, an improved simplified treatment of close and weak pairs is proposed, which is based on long-range cancellations of individually slowly decaying contributions in the amplitude equations. Benchmark calculations for correlation, reaction, and activation energies demonstrate that these approximations work extremely well, while pair approximations based on local second-order Møller-Plesset theory can lead to errors that are 1-2 orders of magnitude larger...
March 28, 2015: Journal of Chemical Physics
Viviane Calice-Silva, Rasha Hussein, Dalia Yousif, Hanjie Zhang, Len Usvyat, Ludimila G Campos, Gero von Gersdorff, Mathias Schaller, Danielle Marcelli, Aileen Grassman, Michael Etter, Xiaoqi Xu, Peter Kotanko, Roberto Pecoits-Filho
BACKGROUND: The number of patients receiving renal replacement therapy (RRT) increases annually and worldwide. Differences in the RRT incidence, prevalence, and modality vary between regions and countries for reasons yet to be clarified. AIMS: Gain a better understanding of the association between hemodialysis (HD)-related variables and general population global health indicators. METHODS: The present study included prevalent HD patients from 27 countries/regions from the monitoring dialysis outcomes (MONDO) database from 2006-2011...
2015: Blood Purification
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