bluuebunny/crossref_metadata_2025 huggingface dataset:
Complications in Total Knee Arthroplasty After High Tibial Osteotomy
Authors: Farfalli Luis A. , Farfalli Germán L. , Aponte-Tinao Luis A.
Published: April 2012

The outcome of total knee arthroplasty (TKA) after high tibial osteotomy remains uncertain. Compared with primary TKA, the results in some studies are not significantly different. Others report adverse effects on the outcome. The purpose of this study was to determine (1) the middle- and long-term survival of TKA performed after high tibial osteotomy, (2) their clinical and radiographic results, and (3) what complications could be expected in this group of patients.

The study group comprised 31 patients (34 knees) undergoing cemented TKA after high tibial osteotomy. Average follow-up was 8 years (range, 6–213 months). Survival of the TKA was estimated using the Kaplan-Meier method. Outcomes were documented using the Hospital for the Special Surgery score. The results showed that the Kaplan-Meier survival rate was 82% at 5 years and 76% at 10 years. Excellent and good clinical results were obtained in 67% of patients. Complications occurred in 12 (35%) knees: stiffness in 4, aseptic loosening in 2, patellofemoral subluxation in 1, instability in 1, inexplicable pain in 1, and deep infection in 3.

Great care with technical details is necessary when high tibial osteotomy is indicated because a future conversion to TKA may occur.
Platelet-rich Plasma Reverses the Inhibition of Tenocytes and Osteoblasts in Tendon–Bone Healing
Authors: Zhai Wenliang , Wang Nan , Qi Zhi , Gao Quan , Yi Liren
Published: April 2012

The purpose of this study was to investigate the effect of platelet-rich plasma on the proliferation of osteoblasts and tenocytes in tendon–bone healing. We cultured osteoblasts and tenocytes in an indirect coculture system with Transwell filters (Merck Millipore, Billerica, Massachusetts). The proliferation was examined using Cell Counting Kit-8 (Dojindo Chemistry Research Institute, Kumamoto, Japan).

Four groups were studied: group 1, one cell type cultured without platelet-rich plasma; group 2, two cell types cultured together in an indirect coculture system without platelet-rich plasma; group 3, cells in the outer chamber and platelet-rich plasma in the inner chamber; and group 4, two different cell types in each of the 2 chambers with platelet-rich plasma in the inner chamber. The proliferation rates of groups 3 and 4 were the highest, followed by group 1 and then group 2, which was the lowest.

Platelet-rich plasma abolishes the inhibition of osteoblasts or tenocytes in an indirect coculture system and improves the cell proliferation rate.
Expansive Open-door Laminoplasty With Titanium Miniplate Versus Sutures
Authors: Chen Guangdong , Luo Zongping , Nalajala Badri , Liu Tao , Yang Huilin
Published: April 2012

Expansive laminoplasty is an effective treatment for cervical myelopathy. Since the design of classic open-door laminoplasty with the use of suture, the procedure has been modified to reduce complications such as restenosis, axial symptoms, and segmental motor paralysis. Expansive open-door laminoplasty with the use of titanium miniplate is becoming popular. It is effective in expanding spinal canal dimensions with good clinical efficacy. However, a lack of studies exist comparing titanium miniplate fixation with classical suture fixation.

We performed a retrospective study of 54 patients with cervical myelopathy. Twenty-nine patients (4 women and 25 men) receiving expansive open-door laminoplasty by titanium miniplate fixation were classified as the modified group, and 25 patients (5 women and 20 men) fixed with suture served as the control group. Clinical and radiologic outcomes were assessed. No significant differences were observed in Japanese Orthopaedic Association scores and the recovery rate of C5 palsy. The incidence of axial symptoms in the modified group was significantly lower than that in control group. Radiologic examination showed that postoperative C2–C7 lordosis and range of motion of the cervical spine in the modified group were preserved. No significant differences were observed in mean anteroposterior diameter and open angle in the 2 groups. Both surgical protocols were effective in preventing reclosure of open laminae. Furthermore, the modified laminoplasty was superior in reducing the incidence of axial symptoms and loss of cervical lordosis and range of motion.
Financial Debt of Orthopedic Residents
Authors: Hwang John S. , Beebe Kathleen S. , Benevenia Joseph , Karanfilian Briette , Berberian Wayne S.
Published: April 2012

Many orthopedic residents accrue considerable debt by residency graduation. These debts for graduating medical students continue to increase due to the yearly increase of medical school tuition. The purpose of this study was to examine the causes of financial debt, as well the effects of debt on orthopedic residents.

Orthopedic residents from postgraduate years 1 to 5 (N=27) completed an anonymous, optional financial survey. The survey asked questions regarding the characteristics of the residents’ debt and their concern caused by their debt. All residents from our institute (N=27) voluntarily participated in the survey. The residents consisted of 4 (15%) women and 23 (85%) men, with 14 (56%) single residents and 12 (44%) married residents. No statistically significant difference existed in total debt >$100,000 between single and married residents or men and women. Forty-eight percent (n=13) of the residents had medical educational debt >$100,000, whereas 45% (n=12) had total debt >$200,000. Residents with total debt >$100,000 were concerned about their debt, whereas 1 of 4 residents with <$100,000 of total debt reported concern (
P
<.001).

Debts affect orthopedic residents financially and may cause stress and hinder their medical training. Appropriate measures should be taken to help residents properly manage their debt and to provide supplemental assistance with their financial struggles.
Familial Association of Femoral Trochlear Dysplasia With Recurrent Bilateral Patellar Dislocation
Authors: Rebolledo Brian J. , Nam Denis , Cross Michael B. , Green Daniel W. , Sculco Thomas P.
Published: April 2012

Femoral trochlear dysplasia is an anatomic deformity that predisposes patients to patellar instability, including patellar subluxation and dislocation, and can lead to severe patellofemoral joint degeneration if left untreated. Femoral trochlear dysplasia leading to recurrent bilateral patellar dislocation has rarely been reported as having a familial association. Orthopedic surgeons who encounter patients presenting with chronic patellar instability with no underlying disease or syndrome should be aware of the presence of femoral trochlear dysplasia leading to recurrent bilateral patellar dislocation. Although femoral trochlear dysplasia remains uncommon, the presence of bilateral recurrent patellar dislocation in multiple members of the same family is highly suggestive of genetic inheritance.

This article describes 3 patients from 1 family who presented with femoral trochlear dysplasia leading to recurrent bilateral patellar dislocation. To our knowledge, this is the second article to describe a familial form of femoral trochlear dysplasia associated with recurrent bilateral patellar dislocation and is the first article in English. A lower threshold for screening and early intervention for symptomatic family members may be indicated to prevent the long-term effects of chronic patellar subluxation, dislocation, and patellofemoral arthritis.
Collagen Type V Polymorphism in Spontaneous Quadriceps Tendon Ruptures
Authors: Galasso Olimpio , Iaccino Enrico , Gallelli Luca , Perrotta Ida , Conforti Francesco , Donato Giuseppe , Gasparini Giorgio
Published: April 2012

Spontaneous simultaneous bilateral quadriceps tendon rupture is associated with multiple medical conditions and pharmacological treatments; however, identifying prior risk factors is impossible in most cases. Achilles tendon and anterior cruciate ligament ruptures are associated with collagen, type V, alpha 1 (COL5A1) polymorphism. This genetic variant may be implicated quadriceps tendon rupture. The COL5A1 encodes the protein for pro-α1 chains of the low-abundance heterotrimeric type V collagen. In most noncartilaginous tissues, type V collagen is a quantitatively minor component of type I collagen that has been implicated in the regulation of the size and configuration of type I collagen fibrils. The functional significance of COL5A1 polymorphism in relation to type V collagen expression or activity has not been determined.

This article describes a patient with COL5A1 polymorphism and spontaneous simultaneous quadriceps tendon rupture. However, genetic and histologic studies performed on blood and tendon tissues and 3 consecutive sex- and age-matched controls showed a statistically significant reduction in collagen type V expression and an alteration in collagen structure in the tendon. These findings might explain the pathomechanisms of spontaneous tendon ruptures associated with COL5A1 polymorphism.
Acute Tibialis Posterior Tendon Rupture Associated With a Distal Tibial Fracture
Authors: Jarvis Hannah C. , Cannada Lisa K.
Published: April 2012

Tibialis posterior tendon ruptures associated with closed medial malleolar fractures are rare. This article describes the association of tibialis posterior tendon ruptures with closed, high-energy, distal tibia fractures. Tendon ruptures are likely to be identified intraoperatively or missed if clinical evaluation at acute injury is limited. A high index of suspicion is required to diagnose this injury. The consequences of an unrecognized tibialis posterior tendon rupture include progressive, painful pes planus deformities due to the unopposed action of the peroneus brevis muscle and lack of support of the medial longitudinal arch. Secondary operative intervention may be required. This article describes an intraoperative tenodesis technique between the tibialis posterior and flexor digitorum longus tendons when direct repair is not possible.

A 48-year-old woman sustained a closed AO/Orthopaedic Trauma Association type 43A right lower-extremity distal tibia fracture and a traumatic left knee arthrotomy. Temporary stabilization with an external fixator was performed, followed by open reduction and internal fixation of the distal tibial fracture 6 days later. A periarticular nonlocking medial plate was applied, and the tibialis posterior tendon was shortened. We performed a direct tenodesis to the flexor digitorum longus tendon. At 1-year follow-up, the patient had made excellent progress, with no detectable muscle weakness, and was able to perform a single-leg toe raise.

A review of the literature suggested which features of radiological evidence of tendon rupture should be examined, which may be useful in the current era considering most high-energy distal tibia or pilon fractures undergo examination with computed tomography.
Intraosseous Median Nerve Entrapment Following Pediatric Posterior Elbow Dislocation
Authors: Bono Kenneth T. , Popp James E.
Published: April 2012

Intra-articular entrapment of the median nerve following reduction of a pediatric posterior elbow dislocation is a rare complication but has been reported in the literature.

This article describes a case of a 7-year-old girl who sustained a posterior elbow dislocation associated with a medial epicondyle fracture and the subsequent intraosseous entrapment of her median nerve. The entrapment is believed to have resulted from new bone formation over the nerve that went unrecognized for nearly 2 years following injury. Routine imaging studies failed to detect the entrapment prior to exploratory surgery. Intra-articular entrapment of the median nerve must be suspected following pediatric elbow dislocation when concentric reduction fails, postreduction images demonstrate joint widening, or the patient has persistent clinical symptoms. This case demonstrates the potential for delay in diagnosis of the cause for neurological impairment following a relatively common injury in the pediatric population.

Objective intraoperative findings and intraoperative micropathology aided in limiting the amount of nerve resected to nonviable portions. Our case demonstrates the potential use of a cable nerve graft to bridge segmental defects in peripheral nerves.
Lower-extremity Soft Tissue Infections With Intra-abdominal Sources
Authors: Harrison Ryan K. , Wilmoth Jill C. , Griesser Michael J. , Granger Jeffrey F.
Published: April 2012

This article describes a series of 3 patients who presented with lower-extremity soft tissue infections. Each patient was treated with prompt debridement by an orthopedic surgeon (J.F.G.) and required at least 1 additional procedure by another surgeon.

These infections vary from superficial cellulitis to rapidly advancing necrotizing fasciitis. At times, the source of these infections is clear. Other times, no obvious source of infection exists, in which case the abdomen must be considered as a possible source of infection. A high level of suspicion, complete history and physical examination, and appropriate ancillary studies are required to make an accurate and prompt diagnosis. Options for the treatment of the intra-abdominal source of infection depend on the etiology of the infection and anatomic location of the process. Psoas abscesses can often be decompressed by an interventional radiologist using computed tomography guidance. In the case of bowel involvement, such as suspected carcinoma or diverticulitis, a general surgeon is necessary. When the appropriate diagnosis is made, soft tissue infections of the thigh often respond to appropriate surgical debridement and antibiotic therapy. It is important to remember the whole patient when evaluating soft tissue infections, especially in the thigh. A low threshold for imaging of the abdomen and pelvis is important, especially when the physical examination or medical history reveals the abdomen as a possible source of infection.
Daptomycin Resistance in Prosthetic Joint Infections
Authors: Sivakumar Brahman , Vijaysegaran Praveen , Chaudhuri Alex , Crawford Scott , Ottley Michael
Published: April 2012

Antimicrobial resistance has been problematic since the advent of antibiotics. Patients with prosthetic joint infections often require prolonged courses of antibiotic therapy, with resistance commonly being the consequence. The rapid evolution of resistance poses a serious challenge in the treatment of infections and creates a need for new agents with novel mechanisms of bactericidal activity. Daptomycin, a cyclic lipopeptide naturally produced by
Streptomyces roseosporus
, is a newer agent approved for use in complicated skin, soft tissue, and prosthetic joint infections. To our knowledge, this article describes the first case of daptomycin-resistant heterogenous vancomycin intermediate-resistant
Staphylococcus aureus
(hVISA) in an 82-year-old man undergoing elective total knee arthroplasty in Queensland, Australia, with a subsequent deep prosthetic joint infection.

A literature review is presented, and the increasing number of multi-resistant organisms and their implications for orthopedics are discussed. Worldwide reports of hVISA are reviewed. To our knowledge, this is the first article to describe daptomycin resistance in prosthetic joint infections. The role of newer antimicrobial agents, such as daptomycin, and strategies to minimize antibiotic resistance are examined.
Hepatitis C Viral Infection as an Associated Risk Factor for Necrotizing Fasciitis
Authors: Scher Danielle , Kanlic Enes , Bader Julia , Ortiz Melchor , Abdelgawad Amr
Published: April 2012

Necrotizing fasciitis is a rare soft tissue infection associated with a high mortality rate. Several risk factors for the development of necrotizing fasciitis have been studied, which has given surgeons insight into the types of patients who are more likely to present with this rapidly progressive infection. The concomitant diagnosis of hepatitis C viral infection has not been reported in the literature previously. In this retrospective study covering a 12-year period in 1 Level I trauma center, 10 (34%) of 29 patients presenting with necrotizing fasciitis had an underlying diagnosis of hepatitis C viral infection. The mortality rate in patients with hepatitis C viral infection was 30% compared with 21% for those without hepatitis C viral infection (
P
=.59). The proportion of patients presenting with the concomitant diagnosis of hepatitis C viral infection and necrotizing fasciitis was statistically greater than that expected from the prevalence of hepatitis C viral infection in the general population (1.8%;
P
<.001).

Our study showed that hepatitis C viral infection is a risk factor for developing necrotizing fasciitis. Although our sample size was too small to show a statistical significance, we believe that a clinically significant increase in mortality of necrotizing fasciitis occurred in patients with concomitant hepatitis C viral infection. Therefore, the presence of hepatitis C viral infection in patients presenting with symptoms of necrotizing fasciitis should raise the clinical suspicion for this diagnosis, with the potential for a worse prognosis.
Bullying in Undergraduate Clinical Nursing Education
Authors: Clarke Colette M. , Kane Deborah J. , Rajacich Dale L. , Lafreniere Kathryn D.
Published: April 2012

Although a limited number of studies have focused on bullying in nursing education to date, all of those studies demonstrate the existence of bullying in clinical settings, where nursing students undertake a significant amount of their nursing education. The purpose of this study was to examine the state of bullying in clinical nursing education among Canadian undergraduate nursing students (
N
= 674) in all 4 years of their nursing program. Results suggest that nursing students experience and witness bullying behaviors at various frequencies, most notably by clinical instructors and staff nurses. Third-year and fourth-year students experience more bullying behaviors than first-year and second-year students. Implications for practice include ensuring that clinical instructors are well prepared for their role as educators. Policies must be developed that address the issue of bullying within nursing programs and within health care facilities where nursing students undertake their clinical nursing education.
Using Debriefing for Meaningful Learning to Foster Development of Clinical Reasoning in Simulation
Authors: Dreifuerst Kristina Thomas
Published: April 2012

Debriefing is critical to learning from simulation experiences, yet the literature reports little research describing best practices within nursing. Debriefing for Meaningful Learning (DML) is a systematic process for debriefing in which teachers and students explicate different aspects of reflection and generate new meanings from simulation experiences. The purpose of this exploratory, quasi-experimental, pretest–posttest study was to test the relationship of DML on the development of clinical reasoning skills in prelicensure nursing students when compared with customary debriefing strategies and on students’ perception of quality of the debriefing experience. Analysis of data demonstrated a greater change in clinical reasoning skills and identification of higher-quality debriefing and a positive correlation between clinical reasoning and perception of quality. Findings demonstrate that DML is an effective debriefing method. It contributes to the body of knowledge supporting the use of debriefing in simulation learning and supports the development of best teaching practices.
Intraocular Lens Tilt and Decentration Measured By Scheimpflug Camera Following Manual or Femtosecond Laser–created Continuous Circular Capsulotomy
Authors: Kránitz Kinga , Miháltz Kata , Sándor Gábor L. , Takacs Agnes , Knorz Michael C. , Nagy Zoltán Z.
Published: April 2012

PURPOSE:

To compare intraocular lens (IOL) decentration and tilt following a circular capsulotomy created with a femtosecond laser (laser CCC) to a manually performed continuous curvilinear capsulorrhexis (manual CCC).

METHODS:

In a prospective, randomized study, a laser CCC (Alcon LenSx Inc) was performed in 20 eyes from 20 patients and a manual CCC was performed in 25 eyes from 25 patients. Intraocular lens decentration and tilt were measured using a Scheimpflug camera (Pentacam, Oculus Optikgeräte GmbH) 1 year after surgery. Uncorrected (UDVA) and corrected distance visual acuity (CDVA) and manifest refraction were also determined postoperatively. Between-group differences of IOL decentration and tilt as well as the correlation between IOL decentration and postoperative refractive changes and between IOL tilt and visual acuity were analyzed.

RESULTS:

Horizontal and vertical tilt were significantly higher in the manual CCC group (
P
=.007 and
P
<.001, respectively). Lenses implanted after manual CCC showed greater horizontal and total decentration (
P
=.034 and
P
=.022, respectively). Significant differences were found in the homogeneity of dichotomized IOL vertical tilt and both horizontal and total decentration distribution (
P
=.008,
P
=.036, and
P
=.017, respectively). Total IOL decentration showed a significant correlation with changes in manifest refraction values between 1 month and 1 year after surgery (R=0.33,
P
=.032). A significant correlation was noted between IOL vertical tilt and CDVA (R
2
=0.17, β=−0.41, 95% confidence limit: −0.69 to −0.13,
P
=.005).

CONCLUSIONS:

Continuous curvilinear capsulorrhexis created with a femtosecond laser resulted in a more stable refractive result and less IOL tilt and decentration than manual CCC.
Diferencias de género en los experimentos económicos
Authors: Jürgen Ergun Selim , García-Muñoz Teresa , Fernanda Rivas María
Published: April 2012

Este artículo revisa la literatura en el área de economía experimental sobre las diferencias de género en cuatro temas destacados: aversión al riesgo, confianza, engaño y liderazgo. Se revisan tanto experimentos realizados en laboratorios como experimentos de campo. Resumimos brevemente las principales características de los experimentos que consideramos y señalamos los principales resultados relacionados con las diferencias de género. La gran mayoría de los artículos que hemos revisado documentan diferencias de género en el comportamiento. Estas diferencias podrían explicarse por los estereotipos de roles sexuales que podrían formarse incluso en edades tempranas y / o diferencias hormonales como la hormona femenina oxitocina, o el estrógeno.
El rompecabezas de las preferencias sociales
Authors: Brandts Jordi , Fatas Enrique
Published: April 2012

Presentamos un breve panorama de la literatura en economía experimental sobre preferencias sociales. En numerosos experimentos, participantes con incentivos económicos están dispuestos a sacrificar parte de sus ingresos materiales para compensar el comportamiento amable de otros o a pagar un precio positivo para castigar el comportamiento de individuos egoístas. En economía todas estas acciones reciben el calificativo de sociales, porque no hay una manera clara de reconciliarlas con alguna forma razonable de egoísmo puro. Nos centramos en juegos de dilemas sociales y queremos transmitir dos mensajes. Primero, la investigación en economía experimental ha producido abundante evidencia que ilustra los componentes sociales de las preferencias de las personas. Segundo, sanciones sociales de diferentes tipos desempeñan un papel importante a la hora de facilitar el comportamiento cooperativo.
Gestión activa de la demanda en mercados eléctricos experimentales
Authors: Barreda-Tarrazona Iván , García-Gallego Aurora , Pavan Marina , Sabater-Grande Gerardo
Published: April 2012

Estudiamos el comportamiento de los consumidores en un mercado de electricidad diseñado en el laboratorio. Los sujetos experimentales toman decisiones sobre la cantidad de electricidad que desean consumir en tres contextos diferentes. En el tratamiento base, los consumidores deciden bajo un sistema de precios fijos, en el que el precio es invariable tanto a la franja horaria de consumo como a las restricciones de la red. Los otros dos contextos corresponden a sistemas dinámicos de precios combinados con incentivos cuyo objetivo es la reducción del consumo en algunas situaciones seleccionadas caracterizadas por una alta congestión de la red. En estas situaciones, en el primer contexto, se bonifica la reducción del consumo en la hora punta por debajo de cierto nivel, mientras que en el segundo, los consumidores son sancionados por consumir en hora punta. Desde una perspectiva de bienestar social, nuestros datos experimentales confirman que un sistema de precios dinámico es más eficiente que uno fijo. Además, un esquema dinámico con sanciones, incluso si es menos preferido por parte de los consumidores, es más efectivo que uno en el que se bonifica la reducción del consumo en hora punta. Un sistema de precios dinámico con bonificaciones presenta una relación equilibrada entre eficiencia y nivel de aceptación por parte de los consumidores.
The negotiation of meaning in EFL learning in the language laboratory
Authors: Rees David
Published: April 2012

Au laboratoire de langues de l’Institut national d'horticulture d'Angers, nous utilisons une méthode interactive pour l'enseignement des langues étrangères. Le principe de cette méthode est de faire communiquer des paires de locuteurs non natifs placés dans une situation de communication où ils ont des problèmes à résoudre. La recherche menée ici, avec plus de 240 étudiants, est un test comparatif de l’apprentissage interactif et de l’apprentissage non interactif. Des tests de mémoire à long terme et de mémoire à court terme sont utilisés pour faire une analyse statistique entre les deux groupes. Les résultats montrent clairement des avantages significatifs pour la mémoire à long terme et la mémoire à court terme dans une situation d’apprentissage interactif, par opposition à une situation d’apprentissage non interactif pendant un cours de deux heures.
A Flexible and Qualitatively Stable Model for Cell Cycle Dynamics Including DNA Damage Effects
Authors: Jeffries Clark D. , Johnson Charles R. , Zhou Tong , Simpson Dennis A. , Kaufmann William K.
Published: April 2012

This paper includes a conceptual framework for cell cycle modeling into which the experimenter can map observed data and evaluate mechanisms of cell cycle control. The basic model exhibits qualitative stability, meaning that regardless of magnitudes of system parameters its instances are guaranteed to be stable in the sense that all feasible trajectories converge to a certain trajectory. Qualitative stability can also be described by the signs of real parts of eigenvalues of the system matrix. On the biological side, the resulting model can be tuned to approximate experimental data pertaining to human fibroblast cell lines treated with ionizing radiation, with or without disabled DNA damage checkpoints. Together these properties validate a fundamental, first order systems view of cell dynamics.

Classification Codes: 15A68
Localization of two-dimensional massless Dirac fermions in a magnetic quantum dot
Authors: Könenberg Martin , Stockmeyer Edgardo
Published: April 2012

We consider a two-dimensional massless Dirac operator

H

in the presence of a perturbed homogeneous magnetic field

B=B_0+b

and a scalar electric potential

V

. For

V\in L_{\rm loc}^p(\mathbb R^2)

,

p\in(2,\infty]

, and

b\in L_{\rm loc}^q(\mathbb R^2)

,

q\in(1,\infty]

, both decaying at infinity, we show that states in the discrete spectrum of

H

are superexponentially localized. We establish the existence of such states between the zeroth and the first Landau level assuming that

V=0

. In addition, under the condition that

b

is rotationally symmetric and that

V

satisfies certain analyticity condition on the angular variable, we show that states belonging to the discrete spectrum of

H

are Gaussian-like localized.
Optimal lower bound of the resonance widths for a Helmholtz tube-shaped resonator
Authors: Martinez André , Nédélec Laurence
Published: April 2012

The study of the resonances of theHelmholtz resonator has been broadly described in previous works (see [11] and references therein). Here, for a simple 2-dimensional resonator in the shape of a tube, we analyze the transition zone where oscillations start to appear. Following a careful analysis, we obtain an optimal lower bound of the width of the resonances.
Dynamische Systeme
Authors: Eliasson Håkan , Hofer Helmut W. , Yoccoz Jean-Christophe
Published: April 2012

This workshop continued the biannual series at Oberwolfach on Dynamical Systems that started as the ”Moser-Zehnder meeting” in 1981. The main themes of the workshop are the new results and developments in the area of dynamical systems, in particular in Hamiltonian systems and symplectic geometry related to Hamiltonian dynamics. Highlights were new results on Arnold diffusion and a new approach to the study of Hamiltonian systems based on pseudoholomorphic curve methods.
Real Analysis, Harmonic Analysis and Applications
Authors: Müller Detlef , Thiele Christoph
Published: April 2012

The workshop has focused on important developments within the last few years in the point of view and methods of real and harmonic Analysis as well as significant concurrent progress in the application of these to various other fields.
Partial Differential Equations
Authors: Ambrosio Luigi , Chang Sun-Yung Alice , Schätzle Reiner , Weiss Georg S.
Published: April 2012

The workshop dealt with partial differential equations in geometry and technical applications. The main topics were the combination of nonlinear partial differential equations and geometric problems, regularity of free boundaries, conformal invariance and the Willmore functional.
Applied Dynamics and Geometric Mechanics
Authors: Bloch Anthony M. , Ratiu Tudor S. , Scheurle Jürgen
Published: April 2012

This one week workshop was organized around several central subjects in applied dynamics and geometric mechanics. The specific organization with afternoons free for discussion led to intense exchanges of ideas. Bridges were forged between researchers representing different fields. Links were established between pure mathematical ideas and applications. The meeting was not restricted to any particular application area. One of the main goals of the meeting, like most others in this series for the past twenty years, has been to facilitate cross fertilization between various areas of mathematics, physics, and engineering. New collaborative projects emerged due to this meeting. The workshop was well attended with participants from Europe, North America, and Asia. Young researchers (doctoral students, postdocs, junior faculty) formed about 30% of the participants.
Mini-Workshop: Dynamics of Stochastic Systems and their Approximation
Authors: Buckwar Evelyn , Gentz Barbara , Hausenblas Erika
Published: April 2012

The aim of this workshop was to bring together specialists in the area of stochastic dynamical systems and stochastic numerical analysis to exchange their ideas about the state of the art of approximations of stochastic dynamics. Here approximations are considered in the analytical sense in terms of deriving reduced dynamical systems, which are less complex, as well as in the numerical sense via appropriate simulation methods. The main theme is concerned with the efficient treatment of stochastic dynamical systems via both approaches assuming that ideas and methods from one ansatz may prove beneficial for the other. A particular goal was to systematically identify open problems and challenges in this area.
Mini-Workshop: New Developments in Newton-Okounkov Bodies
Authors: Harada Megumi , Kaveh Kiumars , Khovanskii Askold
Published: April 2012

The theory of Newton-Okounkov bodies, also called Okounkov bodies, is a new connection between algebraic geometry and convex geometry. It generalizes the well-known and extremely rich correspondence between geometry of toric varieties and combinatorics of convex integral polytopes. Okounkov bodies were first introduced by Andrei Okounkov, in a construction motivated by a question of Khovanskii concerning convex bodies govering the multiplicities of representations. Recently, Kaveh-Khovanskii and Lazarsfeld-Mustata have generalized and systematically developed Okounkov’s construction, showing the existence of convex bodies which capture much of the asymptotic information about the geometry of (

X,D

) where

X

is an algebraic variety and

D

is a big divisor. The study of Okounkov bodies is a new research area with many open questions. The goal of this mini-workshop was to bring together a core group of algebraic/symplectic geometers currently working on this topic to establish the groundwork for future development of this area.
Discrete Geometry
Authors: Matoušek Jiří , Rote Günter , Bárány Imre
Published: April 2012

A number of remarkable recent developments in many branches of discrete geometry have been presented at the workshop, some of them demonstrating strong interactions with other fields of mathematics (such as algebraic geometry, harmonic analysis, and topology). The field is very active with lots of open questions and many solutions. There was a large number of young participants who are eager to work on these problems. The future of discrete geometry looks more than promising.
Noncommutative Geometry
Authors: Connes Alain , Cuntz Joachim , Rieffel Marc A. , Yu Guoliang
Published: April 2012

Noncommutative Geometry applies ideas from geometry to mathematical structures determined by noncommuting variables. This meeting concentrated primarily on those aspects of Noncommutative Geometry that are related to index theory and on the connections between operator algebras and number theory.
Tropical biomass burning smoke plume size, shape, reflectance, and age based on 2001–2009 MISR imagery of Borneo
Authors: Zender C. S. , Krolewski A. G. , Tosca M. G. , Randerson J. T.
Published: April 2012

Abstract. Land clearing for crops, plantations and grazing results in anthropogenic burning of tropical forests and peatlands in Indonesia, where images of fire-generated aerosol plumes have been captured by the Multi-angle Imaging SpectroRadiometer (MISR) since 2001. Here we analyze the size, shape, optical properties, and age of distinct fire-generated plumes in Borneo from 2001–2009. The local MISR overpass at 10:30 a.m. misses the afternoon peak of Borneo fire emissions, and may preferentially sample longer plumes from persistent fires burning overnight. Typically the smoke flows with the prevailing southeasterly surface winds at 3–4 m s−1, and forms ovoid plumes whose mean length, height, and cross-plume width are 41 km, 708 m, and 27% of the plume length, respectively. 50% of these plumes have length between 24 and 50 km, height between 523 and 993 m and width between 18% and 30% of plume length. Length and cross-plume width are lognormally distributed, while height follows a normal distribution. Borneo smoke plume heights are similar to previously reported plume heights, yet Borneo plumes are on average nearly three times longer than previously studied plumes. This could be due to sampling or to more persistent fires and greater fuel loads in peatlands than in other tropical forests. Plume area (median 169 km2, with 25th and 75th percentiles at 99 km2 and 304 km2, respectively) varies exponentially with length, though for most plumes a linear relation provides a good approximation. The MISR-estimated plume optical properties involve greater uncertainties than the geometric properties, and show patterns consistent with smoke aging. Optical depth increases by 15–25% in the down-plume direction, consistent with hygroscopic growth and nucleation overwhelming the effects of particle dispersion. Both particle single-scattering albedo and top-of-atmosphere reflectance peak about halfway down-plume, at values about 3% and 10% greater than at the origin, respectively. The initially oblong plumes become brighter and more circular with time, increasingly resembling smoke clouds. Wind speed does not explain a significant fraction of the variation in plume geometry. We provide a parameterization of plume shape that can help atmospheric models estimate the effects of plumes on weather, climate, and air quality. Plume age, the age of smoke furthest down-plume, is lognormally distributed with a median of 2.8 h (25th and 75th percentiles at 1.3 h and 4.0 h), different from the median ages reported in other studies. Intercomparison of our results with previous studies shows that the shape, height, optical depth, and lifetime characteristics reported for tropical biomass burning plumes on three continents are dissimilar and distinct from the same characteristics of non-tropical wildfire plumes.
Limited-are a modelling of stratocumulus over South-Eastern Pacific
Authors: Andrejczuk M. , Grabowski W. W. , Gadian A. , Burton R.
Published: April 2012

Abstract. This paper presents application of the Weather Research and Forecasting (WRF) model to limited-area modeling of atmospheric processes over the subtropical south-eastern Pacific, with the emphasis on the stratocumulus-topped boundary layer. The simulations cover a domain from the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) field project conducted in the subtropical south-eastern Pacific in October and November 2008. We focus on a day where the UK's BAe-146 research aircraft encountered Pockets of Open Cells (POCs) at the very western edge of its flight track, rather than on the entire campaign as investigated in previous limited-area modeling studies. Model results are compared to aircraft observations with the main conclusion that the simulated stratocumulus-topped boundary layer is significantly too shallow. This appears to be a combination of an already too shallow boundary layer in the dataset used to provide initial and lateral boundary conditions, and the inability of the WRF model to increase the boundary-layer height. Several sensitivity simulations, applying different subgrid-scale parameterizations available in the model, a larger computational domain and longer simulations, as well as a different dataset providing initial and lateral boundary conditions were all tried to improve the simulation. These changes appeared to have a rather small effect on the results. The model does simulate the formation of mesoscale cloud-free regions that one might consider similar to Pockets of Open Cells observed in nature. However, formation of these regions does not seem to be related to drizzle-induced transition from open- to closed-cell circulations as simulated by LES models. Instead, the cloud-free regions appear to result from mesoscale variations of the lower-tropspheric vertical velocity. Areas of negative vertical velocity with minima (a few cm s−1) near the boundary layer top seem to induce direct evaporation of the cloud layer. It remains to be seen in LES studies whether the mechanism seen in the model is realistic or if it is simply an artifact of interactions between resolved and parameterized processes.
Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA-evolution
Authors: Janssen R. H. H. , Vilà-Guerau de Arellano J. , Ganzeveld L. N. , Kabat P. , Jimenez J. L. , Farmer D. K. , van Heerwaarden C. C. , Mammarella I.
Published: April 2012

Abstract. We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to well reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment) must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA) concentration. An examination of the budgets of organic aerosol and terpene concentration shows that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically examine the role of the land surface, which governs both the surface energy balance partitioning and terpene-emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene-emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore it influences the relationship between organic aerosol and terpene-concentrations. Our findings indicate that the diurnal evolution of SOA in the boundary layer is the result of coupled effects of the land surface, dynamics of the atmospheric boundary layer, chemistry, and free troposphere conditions. This has potentially some consequences for the design of both field campaigns and large-scale modeling studies.
A 250 ka oxygen isotope record from diatoms at Lake El'gygytgyn, far east Russian Arctic
Authors: Chapligin B. , Meyer H. , Swann G. E. A. , Meyer-Jacob C. , Hubberten H.-W.
Published: April 2012

Abstract. In 2003 sediment core Lz1024 was drilled at Lake El'gygytgyn, far east Russian Arctic, in an area of the Northern Hemisphere which has not been glaciated for the last 3.6 Ma. Biogenic silica was used for analysing the oxygen isotope composition (δ18Odiatom) in the upper 13 m long section dating back about 250 ka with samples dominated by one taxa in the <10 μm fraction (Cyclotella ocellata). Downcore variations in δ18O values show that glacial-interglacial cycles are present throughout the core and δ18Odiatom values are mainly controlled by δ18Oprecipitation. Changes reflect the Holocene Thermal Maximum, the Last Glacial Maximum and the interglacial periods corresponding to MIS 5e and MIS 7 with a peak-to-peak amplitude of δ18O = 5.3 ‰. Our record is the first continuous δ18Odiatom record from an Arctic lake sediment core directly responding to precipitation and dating back more than 250 ka and correlates well with the stacked marine δ18O LR04 (r = 0.58) and δD EPICA Dome-C record (r = 0.69). With δ18O results indicating strong links to both marine and ice-core records, records from Lake El'gygytgyn can be used to further investigate the sensitivity of the Arctic climate to both past and future global climatic changes.
Accumulation and modeling of particles in drinking water pipe fittings
Authors: Neilands K. , Bernats M. , Rubulis J.
Published: April 2012

Abstract. The effect of pipe fittings – mainly T-pieces – on particle accumulation in drinking water distribution networks is shown in this work. The online measurements of flow and turbidity for cast iron, polyethylene and polyvinylchloride pipe sections have been linked with the analysis of pipe geometry. Up to 0.29 kg of the total mass of particles was found to be accumulated in T-pieces ranging from DN 100/100–DN 250/250. The accumulated amount of particles in the fittings was defined as J and introduced into the existing turbidity model PODDS (Prediction of Discolouration in Distribution Systems) proposed by Boxall et al. (2001), which describes the erosion of particles leading to discoloration events in drinking water networks, viz. sections, of straight pipes. It does not interpret the mobilization of particles in pipe fittings, however, which have been considered in this article. T-pieces were the object of this study and depending on the diameter or daily flow velocity, the coefficient J varied from 1.16 to 8.02.
Multimodel evaluation of twenty lumped hydrological models under contrasted climate conditions
Authors: Seiller G. , Anctil F. , Perrin C.
Published: April 2012

Abstract. This paper investigates the temporal transposability of hydrological models under contrasted climate conditions and evaluates the added value of using an ensemble of model structures for flow simulation. This is achieved by applying the Differential Split Sample Test procedure to twenty lumped conceptual models on a catchment in the Province of Québec (Canada) and another one in the State of Bavaria (Germany). First, a calibration/validation procedure was applied on four historical non-continuous periods with contrasted climate conditions. Then, model efficiency was quantified individually (for each model) and collectively (for the model ensemble). The individual analysis evaluated model performance and robustness. The ensemble investigation, based on the average of simulated discharges, focused on the twenty-member ensemble and all possible model subsets. Results showed that using a single model may provide hazardous results when the model is to be applied in contrasted conditions. Overall, some models turned out as a good compromise in terms of performance and robustness, but generally not as much as the twenty-model ensemble. Model subsets offered yet improved performance over the twenty-model ensemble, but at the expanse of spatial transposability (i.e. need of site-specific analysis).
In Vitro Hemodynamic Evaluation of Ventricular Suction Conditions of the EVAHEART Ventricular Assist Pump
Authors: Ferreira Antonio L. , Yu Yih-Choung , Arnold Dorian K. , Vandenberghe Stijn , Grashow Jonathan , Kitano Tomoya , Borzelleca David , Antaki James F.
Published: April 2012

Purpose:

Mismatches between pump output and venous return in a continuous-flow ventricular assist device may elicit episodes of ventricular suction. This research describes a series of in vitro experiments to characterize the operating conditions under which the EVAHEART centrifugal blood pump (Sun Medical Technology Research Corp., Nagano, Japan) can be operated with minimal concern regarding left ventricular (LV) suction.

Methods:

The pump was interposed into a pneumatically driven pulsatile mock circulatory system (MCS) in the ventricular apex to aorta configuration. Under varying conditions of preload, afterload, and systolic pressure, the speed of the pump was increased step-wise until suction was observed. Identification of suction was based on pump inlet pressure.

Results:

In the case of reduced LV systolic pressure, reduced preload (≤10 mmHg), and afterload (≤60 mmHg), suction was observed for speeds ≥2,200 rpm. However, suction did not occur at any speed (up to a maximum speed of 2,400 rpm) when preload was kept within 10–14 mmHg and afterload ≥80 mmHg. Although in vitro experiments cannot replace in vivo models, the results indicated that ventricular suction can be avoided if sufficient preload and afterload are maintained.

Conclusion:

Conditions of hypovolemia and/or hypotension may increase the risk of suction at the highest speeds, irrespective of the native ventricular systolic pressure. However, in vitro guidelines are not directly transferrable to the clinical situation; therefore, patient-specific evaluation is recommended, which can be aided by ultrasonography at various points in the course of support.