bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of herbaceous competition and drainage conditions on the early productivity of willows under short-rotation intensive culture
Authors: Labrecque Michel , Teodorescu Traian Ion , Babeux Patrice , Cogliastro Alain , Daigle Stéphane
Published: March 2008

The productivity of trees under short-rotation intensive culture is influenced by herbaceous competition and drainage conditions. During the first year of establishment of Salixdiscolor Mühl. and Salixviminalis L., four weed-suppression treatments were applied to two sites showing different drainage conditions, one well drained and the other is poorly drained. On the well-drained site, the productivity of the trees increased in all the plots under treatment, whereas on the poorly drained site, only the use of a plastic mulch increased the biomass production. The mean productivity on the well-drained site was always superior to the productivity measured on the poorly drained site except when the vegetation was controlled by the use of a plastic mulch. The analyses related to nutrition revealed that the trees on the well-drained site absorbed more nutrients than those on the poorly drained site. Salixdiscolor showed a higher uptake of potassium and S. viminalis, a higher concentration of calcium. Our results indicate that weed suppression is essential to the establishment of trees in short-rotation intensive culture and that the use of a plastic mulch proved to be particularly profitable on marginal sites.
The informational efficiency of the Vancouver Log Market and the financial risk of holding logs in storage
Authors: Zhang Daowei , Binkley Clark S.
Published: March 2008

Viewed on an annual or quarterly basis, the Vancouver Log Market appears to process price information efficiently, but apparently does not do so for monthly trading intervals. For the longer holding periods the Vancouver Log Market passes one of the fundamental tests for an efficient market, and as a consequence there are few gains to make by speculating in this market on the basis of technical analysis of past price movements. Explanations for lack of information efficiency in the monthly returns requires further study. Holding logs does not appear to entail a significant amount of systematic or market risk if the holding periods are one quarter or less. Producers can hold log inventories in the Vancouver Log Market without increasing the financial risk of their enterprises.
Field performance potential of interior spruce seedlings: effects of stress treatments and prediction by root growth potential and needle conductance
Authors: Simpson David G. , Thompson C.F. , Sutherland Craig D.
Published: March 2008

Root growth potential (RGP) and needle conductance to water vapour (Gn) of container-grown interior spruce (Piceaglauca–(Moench) Voss Piceaengelmannii Parry complex) seedlings that had been subjected to mechanical (dropping), low-temperature (−15 °C), or heat (35 °C) stresses were determined prior to planting on two forest sites. Field performance measured as survival, height, stem diameter, stem volume, and mean stem volume relative growth rate (RGR) was assessed for each of the 4 years following planting. RGP, Gn, and field performance did not differ between mechanically stressed and nonstressed seedlings. Low temperature and heat stresses reduced RGP, Gn, and field performance of some batches of seedlings, indicating that stock lots with different nursery cultural history had substantially different stress resistance. RGP and Gn were correlated with field performance such that for RGP greater than five new roots per seedling, high (>80%) survival and to a lesser extent greater growth occurred, whereas for RGP less than five new roots per seedling, survival and growth were unpredictable. High survival and better growth occurred for stock lots having Gn > 50 mmol•m−2•s−1, while for Gn < 50 mmol•m−2•s−1, survival decreased. Preplanting stress effects on growth were small and due to RGR reductions in the first field season, which are projected to result in a time delay of 1 year or less in trees reaching a height of 150 cm and a stem diameter of 3.5 cm.
Photosynthesis, water relations, and leaf morphology of xeric versus mesic Quercusrubra ecotypes in central Pennsylvania in relation to moisture stress: Reply. Quercusrubra ecotypes revisited
Authors: Abrams Marc D. , Kubiske Mark E.
Published: March 2008

not available
Sulfur speciation, vertical distribution, and seasonal variation in a northern hardwood forest soil, U.S.A
Authors: Dhamala B.R. , Mitchell M.J.
Published: March 2008

Sulfur biogeochemistry of a northern hardwood forest soil in Bear Brook Watershed, Maine, was studied utilizing 35S in situ. The objectives of study were to characterize different S pools, their vertical distribution, and seasonal variation. Soil cores were used at the field and treated with 35SO42−. The distribution of total and C-bonded S followed a typical pattern of decreasing concentration with soil depth. More than 86% of total 35S added was retained by the soil. Most of the 35S activity was in the organic S pool (up to 73 and 20% of total 35S in C-bonded S and ester-sulfate forms, respectively) in both the forest floor and the mineral soil horizons. Ester sulfate increased with depth from 5.3 to 25.5% of total S. During the summer the relative importance of mineralization to immobilization decreased. Inorganic sulfate was the smallest S pool. However, higher specific activity and turnover rate of the inorganic 35SO42− pool than organic 35S pool indicated that S concentration and solution flux were more regulated by abiotic (adsorption and desorption) than biotic (mineralization and immobilization) processes.
Enlargement of tree-mortality centers surrounding pine stumps infected by Hetetobasidionannosum in northeastern California
Authors: Slaughter G.W. , Parmeter Jr. J.R.
Published: March 2008

Enlargement of 53 tree-mortality centers surrounding pine stumps infected for about 35 years by Heterobasidionannosum (Fr.) Bref, was studied in northeastern California. At the end of the study period (1992), mean area for all centers was 209 m2 (range 16–701 m2), and the mean rate of radial enlargement was 0.22 m/year (0.7 ft/year). Rates decreased over time and center enlargement essentially ceased at most centers 20–30 years after stump infection. However, 7 centers (13%) continued to enlarge into surrounding stands at a mean rate of radial enlargement of 0.39 m/year (1.3 ft/year), and averaged 557 m2 (0.14 acre) by 1992. Continued enlargement of centers and extension of mortality beyond center stump root zones were associated with adjacent dead trees larger than 20 cm DBH. Many individual centers had different rates of enlargement at different points along their boundaries, ranging from 0 to 0.78 m/year (2.5 ft/year).
Conifer seedling distribution in relation to microsite conditions in a central New York forested minerotrophic peatland
Authors: St. Hilaire Lisa R. , Leopold Donald J.
Published: March 2008

This study addressed how microsite conditions may affect tree regeneration in a forested minerotrophic peatland in central New York. The objectives were to (i) determine the microsite associations, especially the bryophyte component, of Abiesbalsamea (L.) Mill., Thujaoccidentalis L., Tsugacanadensis (L.) Carr., and Pinusstrobus L. seedlings and (ii) determine if different bryophyte substrates affect germination of A. balsamea, Thujaoccidentalis, and P. strobus, and first-year survival of A. balsamea and P. strobus. Principal components analysis revealed that seedling groups overlap in habitat, but separate from random sites based on a second axis related to microtopography. Germination experiments indicate that A. balsamea and P. strobus germinate better on Hypnumimponens than on Hylocomiumsplendens and Sphagnumgirgensohnii in the field, but not in the greenhouse. First-year survival differed little on the different mosses.
Above- and below-stump biomass and nutrient content of a mature loblolly pine plantation
Authors: Van Lear D.H. , Kapeluck P.R.
Published: March 2008

Above- and below-stump biomass and nutrient content were estimated for a mature loblolly pine (Pinustaeda L.) plantation on an eroded site in the upper Piedmont of South Carolina. Pine above-stump biomass was 144.9 t•ha−1; below-stump biomass was 36.0 t•ha−1, 20% of total pine biomass. Total pine biomass was partitioned as 17% crown, 63% stem, and 20% roots. About 55% of below-stump biomass was in taproots and 45% in lateral roots. Dominant and codominant trees had a greater proportion of below-stump biomass in lateral roots, indicating that larger trees absorb a disproportionate quantity of the site's moisture and nutrients. Lateral roots contained 66 to 75% of below-stump nutrients. Fine roots (<0.6 cm diameter) accounted for 11% of below-stump biomass, but contained 24 to 30% of below-stump nutrients. Nutrient content (kg•ha−1) of above-stump biomass ranked as follows: N 164.7, Ca 154.2, K 78.0, and P 14.0. Nitrogen was also the most abundant nutrient in below-stump biomass (60.2 kg•ha−1), followed by Ca (48.9 kg•ha−1), K (41.2 kg•ha−1), Mg (11.1 kg•ha−1), and P (7.5 kg•ha−1). Below-stump biomass contained 27, 35, 35, and 24% of total pine N, P, K, and Ca, respectively. Fine roots and foliage, only 4% of total stand biomass, had about one-fourth of the stand's N and P.
A NOTE ON A PIECEWISE-LINEAR DUFFING-TYPE SYSTEM
Authors: TIGAN GHEORGHE , ASTOLFI ALESSANDRO
Published: March 2008

In [Tonnelier, 2005] it was suggested that the number of limit cycles in a piecewise-linear system could be closely related to the number of zones, that is, the number of parts of the phase plane where the system is linear. In this note, we construct an example of a class of perturbed piecewise systems with n zones such that the first variation of the displacement function is identically zero. Then we conjecture that the system has no limit cycles using the second variation of the displacement function expressed for continuous functions. This system can be seen as a feedback system in control theory.
INFLUENCE OF UNIFORM NOISE ON TWO LIGHT-CONTROLLED OSCILLATORS
Authors: RAMÍREZ ÁVILA GONZALO M. , GUISSET JEAN-LUC , DENEUBOURG JEAN-LOUIS
Published: March 2008

We study the influence of uniform noise on a system of two light-controlled oscillators (LCOs) under three different configurations: uncoupled, master–slave and mutually coupled LCOs. We find that noise can induce desynchronization via a phase transition-like phenomenon depending on the noise intensity and the characteristics of the LCOs.
SAMPLING IN DYNAMIC DATA STREAMS AND APPLICATIONS
Authors: FRAHLING GEREON , INDYK PIOTR , SOHLER CHRISTIAN
Published: March 2008

A dynamic geometric data stream is a sequence of m ADD/REMOVE operations of points from a discrete geometric space {1,…, Δ} d ?. ADD (p) inserts a point p from {1,…, Δ} d into the current point set P , REMOVE(p) deletes p from P . We develop low-storage data structures to (i) maintain ε-nets and ε-approximations of range spaces of P with small VC-dimension and (ii) maintain a (1 + ε)-approximation of the weight of the Euclidean minimum spanning tree of P . Our data structure for ε-nets uses [Formula: see text] bits of memory and returns with probability 1 – δ a set of [Formula: see text] points that is an e-net for an arbitrary fixed finite range space with VC-dimension [Formula: see text]. Our data structure for ε-approximations uses [Formula: see text] bits of memory and returns with probability 1 – δ a set of [Formula: see text] points that is an ε-approximation for an arbitrary fixed finite range space with VC-dimension [Formula: see text]. The data structure for the approximation of the weight of a Euclidean minimum spanning tree uses O ( log (1/δ)( log Δ/ε) O ( d )) space and is correct with probability at least 1 – δ.

Our results are based on a new data structure that maintains a set of elements chosen (almost) uniformly at random from P .
SKIP QUADTREES: DYNAMIC DATA STRUCTURES FOR MULTIDIMENSIONAL POINT SETS
Authors: EPPSTEIN DAVID , GOODRICH MICHAEL T. , SUN JONATHAN Z.
Published: March 2008

We present a new multi-dimensional data structure, which we call the skip quadtree (for point data in R2) or the skip octree (for point data in Rd, with constant d > 2). Our data structure combines the best features of two well-known data structures, in that it has the well-defined “box”-shaped regions of region quadtrees and the logarithmic-height search and update hierarchical structure of skip lists. Indeed, the bottom level of our structure is exactly a region quadtree (or octree for higher dimensional data). We describe efficient algorithms for inserting and deleting points in a skip quadtree, as well as fast methods for performing point location, approximate range, and approximate nearest neighbor queries.
Blood circulation laboratory investigations with video are less investigative than instructional blood circulation laboratories with live organisms
Authors: Hoover Mildred A. , Pelaez Nancy J.
Published: March 2008

Live organisms versus digital video of the organisms were used to challenge students' naive ideas and misconceptions about blood, the heart, and circulatory patterns. Three faculty members taught 259 grade 10 biology students in a California high school with students from diverse ethnolinguistic groups who were divided into 5 classes using microscopes (128 students) and 5 classes using digital video (131 students) to compare blood transport among invertebrates, fish, and humans. The “What Is Happening in this Class?” (WIHIC) questionnaire was used for assessment of microscope and video groups to detect students' perception of their learning environment following these teaching interventions. The use of microscopes had a clear effect on the perception of the investigative aspects of the learning environment that was not detected with the video treatment. Findings suggest that video should not replace investigations with live organisms.
Student perceptions and use of an assessment rubric for a group concept map in physiology
Authors: Moni Roger W. , Moni Karen B.
Published: March 2008

We previously reported how the opinions of second-year dentistry students and faculty members can be used to construct an assessment rubric to grade group-based concept maps in physiology ( 14 ). This article describes the second phase of this study of the subsequent year's cohort. A case study approach was used to investigate how groups of students used the criteria to complete their complex concept maps. Students' opinions about the assessment task and newly constructed rubric were sampled. Opinions across groups were correlated to academic achievements in the course. Two groups of four students volunteered to be videorecorded during a 4-h workshop, during which they completed their maps. The mapping task was not generally favored by students. However, those students who did favor the task achieved higher academic grades. Most students favored the newly constructed assessment rubric, commenting that it was easy to understand, fair, and appropriate, but reported that extra guidance from tutors and other resources were required. Coded videorecordings of the two observation groups revealed complex interactions around the three criteria of content, logic and understanding, and presentation. Two broad patterns of working were identified. One group distributed their efforts more evenly across the criteria, whereas the other group completed their maps by addressing the criteria in stages. These findings clearly indicate the academic challenges and social complexity in how students work in groups to complete complex concept maps in physiology.
Learning approaches of undergraduate medical students to physiology in a non-PBL- and partially PBL-oriented curriculum
Authors: Abraham R. R. , Vinod P. , Kamath M. G. , Asha K. , Ramnarayan K.
Published: March 2008

Melaka Manipal Medical College (Manipal Campus; Manipal, Karnataka, India) conducts the Bachelor of Medicine and Bachelor of Surgery program, for which the admission intakes are during the months of March and September. The present study was undertaken to study the differences in learning approaches to physiology of undergraduate medical students in a partially problem-based learning (PBL)- and non-PBL-oriented curriculum. PBL was introduced as a curricular reform for the September 2006 batch of students (partially PBL group), whereas it was not incorporated for the March 2006 batch of students (non-PBL group). Learning approaches to physiology of both groups of students were compared using the short inventory of approaches to learning. Mean scores for deep and strategic approaches were found to be significantly higher for the partially PBL group compared with the non-PBL group. The results of the present study support the earlier observation that PBL promotes a deep approach to learning.
Hybrid lecture-online format increases student grades in an undergraduate exercise physiology course at a large urban university
Authors: McFarlin Brian K.
Published: March 2008

Hybrid courses allow students additional exposure to course content that is not possible in a traditional classroom environment. This exposure may lead to an improvement in academic performance. In this report, I describe the transition of a large undergraduate exercise physiology course from a traditional lecture format to a hybrid lecture-online format. A total of 658 final grades (traditional = 346, hybrid = 312) was used to evaluate the effect of course format on academic performance. The hybrid online portion was delivered using WebCT Vista, enhanced with various instructional technologies. The hybrid lecture portion was enhanced with an in-class response system. PowerPoint files were used to distribute in-class lectures in both formats of the course. Final student grades were 9.9% higher (83% of the increase due to an increase in the exam grade) when the course was administered in a hybrid format ( P = 0.01), which translated to a one letter grade increase on a standard grading scale. Transition from a traditional lecture format to a hybrid format significantly enhanced student learning; presumably, this increase is due to the fact that students were able to increase their exposure to course content via access to material on WebCT.
Percutaneous and Minimally Invasive Valve Procedures
Authors: Rosengart Todd K. , Feldman Ted , Borger Michael A. , Vassiliades Thomas A. , Gillinov A. Marc , Hoercher Katherine J. , Vahanian Alec , Bonow Robert O. , O’Neill William
Published: March 2008

The incidence of valvular heart disease is expected to increase over the next several decades as a large proportion of the US demographic advances into the later decades of life. At the same time, the next several years can be anticipated to bring a broad transition of surgical therapy to minimally invasive (minithoracotomy and small port) access and the more gradual introduction of percutaneous approaches for the correction of valvular heart disease. Broad acceptance of these technologies will require careful and sometimes perplexing comparisons of the outcomes of these new technologies with existing standards of care. The validation of percutaneous techniques, in particular, will require the collaboration of cardiologists and cardiac surgeons in centers with excellent surgical and catheter experience and a commitment to trial participation. For the near term, percutaneous techniques will likely remain investigational and will be limited in use to patients considered to be high risk or to inoperable surgical candidates. Although current-generation devices and techniques require significant modification before widespread clinical use can be adopted, it must be expected that less invasive and even percutaneous valve therapies will likely have a major impact on the management of patients with valvular heart disease over the next several years.
Human Apolipoprotein A-I Gene Transfer Reduces the Development of Experimental Diabetic Cardiomyopathy
Authors: Van Linthout Sophie , Spillmann Frank , Riad Alexander , Trimpert Christiane , Lievens Joke , Meloni Marco , Escher Felicitas , Filenberg Elena , Demir Okan , Li Jun , Shakibaei Mehdi , Schimke Ingolf , Staudt Alexander , Felix Stephan B. , Schultheiss Heinz-Peter , De Geest Bart , Tschöpe Carsten
Published: March 2008

Background—

The hallmarks of diabetic cardiomyopathy are cardiac oxidative stress, intramyocardial inflammation, cardiac fibrosis, and cardiac apoptosis. Given the antioxidative, antiinflammatory, and antiapoptotic potential of high-density lipoprotein (HDL), we evaluated the hypothesis that increased HDL via gene transfer (GT) with human apolipoprotein (apo) A-I, the principal apolipoprotein of HDL, may reduce the development of diabetic cardiomyopathy.

Methods and Results—

Intravenous GT with 3×10
12
particles/kg of the E1E3E4-deleted vector
Ad.hapoA-I
, expressing human apoA-I, or
Ad.Null
, containing no expression cassette, was performed 5 days after streptozotocin (STZ) injection. Six weeks after apoA-I GT, HDL cholesterol levels were increased by 1.6-fold (
P
<0.001) compared with diabetic controls injected with the
Ad.Null
vector (STZ-
Ad.Null
). ApoA-I GT and HDL improved LV contractility in vivo and cardiomyocyte contractility ex vivo, respectively. Moreover, apoA-I GT was associated with decreased cardiac oxidative stress and reduced intramyocardial inflammation. In addition, compared with STZ-
Ad.Null
rats, cardiac fibrosis and glycogen accumulation were reduced by 1.7-fold and 3.1-fold, respectively (
P
<0.05). Caspase 3/7 activity was decreased 1.2-fold (
P
<0.05), and the ratio of Bcl-2 to Bax was upregulated 1.9-fold (
P
<0.005), translating to 2.1-fold (
P
<0.05) reduced total number of cardiomyocytes with apoptotic characteristics and 3.0-fold (
P
<0.005) reduced damaged endothelial cells compared with STZ-
Ad.Null
rats. HDL supplementation ex vivo reduced hyperglycemia-induced cardiomyocyte apoptosis by 3.4-fold (
P
<0.005). The apoA-I GT-mediated protection was associated with a 1.6-, 1.6-, and 2.4-fold induction of diabetes-downregulated phospho to Akt, endothelial nitric oxide synthase, and glycogen synthase kinase ratio, respectively (
P
<0.005).

Conclusion—

ApoA-I GT reduced the development of streptozotocin-induced diabetic cardiomyopathy.
Vernakalant Hydrochloride for Rapid Conversion of Atrial Fibrillation
Authors: Roy Denis , Pratt Craig M. , Torp-Pedersen Christian , Wyse D. George , Toft Egon , Juul-Moller Steen , Nielsen Tonny , Rasmussen S. Lind , Stiell Ian G. , Coutu Benoit , Ip John H. , Pritchett Edward L.C. , Camm A. John
Published: March 2008

Background—

The present study assessed the efficacy and safety of vernakalant hydrochloride (RSD1235), a novel compound, for the conversion of atrial fibrillation (AF).

Methods and Results—

Patients were randomized in a 2:1 ratio to receive vernakalant or placebo and were stratified by AF duration of 3 hours to 7 days (short duration) and 8 to 45 days (long duration). A first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes, followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if AF was not terminated. The primary end point was conversion of AF to sinus rhythm for at least 1 minute within 90 minutes of the start of drug infusion in the short-duration AF group. A total of 336 patients were randomized and received treatment (short duration, n=220; long duration, n=116). Of the 145 vernakalant patients, 75 (51.7%) in the short-duration AF group converted to sinus rhythm (median time, 11 minutes) compared with 3 of the 75 placebo patients (4.0%;
P
<0.001). Overall, in the short- and long-duration AF groups, 83 of the 221 vernakalant patients (37.6%) experienced termination of AF compared with 3 of the 115 placebo patients (2.6%;
P
<0.001). Transient dysgeusia and sneezing were the most common side effects in vernakalant-treated patients. Four vernakalant-related serious adverse events (hypotension [2 events], complete atrioventricular block, and cardiogenic shock) occurred in 3 patients.

Conclusion—

Vernakalant demonstrated rapid conversion of short-duration AF and was well tolerated.
Epicardium-Derived Cells in Development of Annulus Fibrosis and Persistence of Accessory Pathways
Authors: Kolditz Denise P. , Wijffels Maurits C.E.F. , Blom Nico A. , van der Laarse Arnoud , Hahurij Nathan D. , Lie-Venema Heleen , Markwald Roger R. , Poelmann Robert E. , Schalij Martin J. , Gittenberger-de Groot Adriana C.
Published: March 2008

Background—

The developmental mechanisms underlying the persistence of myocardial accessory atrioventricular pathways (APs) that bypass the annulus fibrosis are mainly unknown. In the present study, we investigated the role of epicardium-derived cells (EPDCs) in annulus fibrosis formation and the occurrence of APs.

Methods and Results—

EPDC migration was mechanically inhibited by in ovo microsurgery in quail embryos. In ovo ECGs were recorded in wild-type (n=12) and EPDC-inhibited (n=12) hearts at Hamburger-Hamilton (HH) stages 38 to 42. Subsequently, in these EPDC-inhibited hearts (n=12) and in additional wild-type hearts (n=45; HH 38–42), ex ovo extracellular electrograms were recorded. Electrophysiological data were correlated with differentiation markers for cardiomyocytes (MLC2a) and fibroblasts (periostin). In ovo ECGs showed significantly shorter PR intervals in EPDC-inhibited hearts (45±10 ms) than in wild-type hearts (55±8 ms, 95% CI 50 to 60 ms,
P
=0.030), whereas the QRS durations were significantly longer in EPDC-inhibited hearts (29±14 versus 19±2 ms, 95% CI 18 to 21 ms,
P
=0.011). Furthermore, ex ovo extracellular electrograms (HH 38–42) displayed base-first ventricular activation in 44% (20/45) of wild-type hearts, whereas in all EPDC-inhibited hearts (100%, 12/12), the ventricular base was activated first (
P
<0.001). Small periostin- and MLC2a-positive APs were found mainly in the posteroseptal region of both wild-type and EPDC-inhibited hearts. Interestingly, in all (n=10) EPDC-inhibited hearts, additional large periostin-negative and MLC2a-positive APs were found in the right and left lateral free wall coursing through marked isolation defects in the annulus fibrosis until the last stages of embryonic development.

Conclusions—

EPDCs play an important role in annulus fibrosis formation. EPDC outgrowth inhibition may result in marked defects in the fibrous annulus with persistence of large APs, which results in ventricular preexcitation on ECG. These APs may provide a substrate for postnatally persistent reentrant arrhythmias.
Restrictive Left Ventricular Filling Pattern Does Not Result From Increased Left Atrial Pressure Alone
Authors: Masutani Satoshi , Little William C. , Hasegawa Hiroshi , Cheng Heng-Jie , Cheng Che-Ping
Published: March 2008

Background—

The restrictive filling pattern seen with severe heart failure (HF) may be due to diastolic dysfunction with elevated left ventricular (LV) diastolic pressure or may be merely a manifestation of an overfilled LV as a result of increased left atrial (LA) pressure. We investigated whether the LV restrictive filling pattern is due to elevated LA pressure alone.

Methods and Results—

We studied conscious dogs instrumented to measure LA pressure, LV pressure, and 3 LV diameters. LV filling dynamics were evaluated in 2 situations with similar elevations of LA pressure: in normal animals after rapid volume loading with dextran 500 mL and in animals with pacing-induced HF with restrictive filling. With HF, there was increased LV chamber stiffness and slow relaxation. Volume loading and HF had similar heart rates (129±19 versus 131±15 bpm) and LA pressure (22.1±5.8 versus 22.6±3.3 mm Hg). The peak early filling rate (E) was increased with both HF and volume loading. However, in HF, the peak mitral annular velocity (E′) was decreased and delayed, and the E deceleration time was shorter. In contrast, with volume loading, E′ was increased and not delayed.

Conclusion—

The restrictive filling pattern is distinguished from overfilling of a normal ventricle by a reduced and delayed E′ and a shortened E deceleration time that reflect slow relaxation and increased LV stiffness.
Magnetic Resonance Imaging Overestimates Ferumoxide-Labeled Stem Cell Survival After Transplantation in the Heart
Authors: Terrovitis John , Stuber Matthias , Youssef Amr , Preece Steve , Leppo Michelle , Kizana Eddy , Schär Michael , Gerstenblith Gary , Weiss Robert G. , Marbán Eduardo , Abraham M. Roselle
Published: March 2008

Background—

Stem cell labeling with iron oxide (ferumoxide) particles allows labeled cells to be detected by magnetic resonance imaging (MRI) and is commonly used to track stem cell engraftment. However, the validity of MRI for distinguishing surviving ferumoxide-labeled cells from other sources of MRI signal, for example, macrophages containing ferumoxides released from nonsurviving cells, has not been thoroughly investigated. We sought to determine the relationship between the persistence of iron-dependent MRI signals and cell survival 3 weeks after injection of syngeneic or xenogeneic ferumoxides-labeled stem cells (cardiac-derived stem cells) in rats.

Methods and Results—

We studied nonimmunoprivileged human and rat cardiac-derived stem cells and human mesenchymal stem cells doubly labeled with ferumoxides and β-galactosidase and injected intramyocardially into immunocompetent Wistar-Kyoto rats. Animals were imaged at 2 days and 3 weeks after stem cell injection in a clinical 3-T MRI scanner. At 2 days, injection sites of xenogeneic and syngeneic cells (cardiac-derived stem cells and mesenchymal stem cells) were identified by MRI as large intramyocardial signal voids that persisted at 3 weeks (50% to 90% of initial signal). Histology (at 3 weeks) revealed the presence of iron-containing macrophages at the injection site, identified by CD68 staining, but very few or no β-galactosidase–positive stem cells in the animals transplanted with syngeneic or xenogeneic cells, respectively.

Conclusions—

The persistence of significant iron-dependent MRI signal derived from ferumoxide-containing macrophages despite few or no viable stem cells 3 weeks after transplantation indicates that MRI of ferumoxide-labeled cells does not reliably report long-term stem cell engraftment in the heart.
Ablation of Matrix Metalloproteinase-9 Increases Severity of Viral Myocarditis in Mice
Authors: Cheung Caroline , Marchant David , Walker Elizabeth K.-Y. , Luo Zongshu , Zhang Jingchun , Yanagawa Bobby , Rahmani Maziar , Cox Jennifer , Overall Christopher , Senior Robert M. , Luo Honglin , McManus Bruce M.
Published: March 2008

Background—

Coxsackievirus B3 (CVB3) causes human myocarditis, which can result in cardiac damage, maladaptive remodeling, and heart failure. Matrix metalloproteinases (MMP)-8 and -9 have been identified in virus-infected myocardium, but their particular roles and underlying mechanisms of effect are unknown. For the first time, we examine the severity of CVB3-induced myocarditis in MMP-8–and MMP-9–deficient mice.

Methods and Results—

CVB3-infected MMP-8 and MMP-9 knockout (KO) mice and corresponding wild-type (WT) mice were euthanized and harvested at 9 days after infection. Expression of MMP-2, -8, -12, and -13 and tissue inhibitors of MMPs was assessed by zymography or immunoblotting on harvested hearts, and in situ hybridization was performed to detect active infection. Infected MMP-9 KO mice had greater myocardial injury and foci of infection than WT mice despite similar pancreatic infection. Increased fibrosis (10.6±2.7% versus 7.1±2.6%,
P
=0.04), viral titer, as well as decreased cardiac output, were evident in MMP-9 KO compared with WT mice as assessed by picrosirius red staining, plaque assay, and echocardiography, respectively. Immune infiltration was also greatly increased in MMP-9 KO compared with WT mice (15.2±12.6% versus 2.0±3.0%,
P
<0.002). Myocardial interferon-β1, interferon-γ, interleukin-6, interleukin-10, and macrophage inflammatory protein-1α expression was elevated in MMP-9 KO mice as measured by quantitative real-time polymerase chain reaction and ELISA. In contrast, MMP-8 KO mice had the same degree of cardiac injury, fibrosis, and viral infection as their WT counterparts.

Conclusions—

During acute CVB3 infection, MMP-9 appears necessary to halt virus propagation in the heart, promote proper immune infiltration and remodeling, and preserve cardiac output.
Survivin Determines Cardiac Function by Controlling Total Cardiomyocyte Number
Authors: Levkau Bodo , Schäfers Michael , Wohlschlaeger Jeremias , von Wnuck Lipinski Karin , Keul Petra , Hermann Sven , Kawaguchi Naomasa , Kirchhof Paulus , Fabritz Larissa , Stypmann Jörg , Stegger Lars , Flögel Ulrich , Schrader Jürgen , Fischer Jens W. , Hsieh Patrick , Ou Yen-Ling , Mehrhof Felix , Tiemann Klaus , Ghanem Alexander , Matus Marek , Neumann Joachim , Heusch Gerd , Schmid Kurt W. , Conway Edward M. , Baba Hideo A.
Published: March 2008

Background—

Survivin inhibits apoptosis and regulates cell division in many organs, but its function in the heart is unknown.

Methods and Results—

We show that cardiac-specific deletion of survivin resulted in premature cardiac death. The underlying cause was a dramatic reduction in total cardiomyocyte numbers as determined by a stereological method for quantification of cells per organ. The resulting increased hemodynamic load per cell led to progressive heart failure as assessed by echocardiography, magnetic resonance imaging, positron emission tomography, and invasive catheterization. The reduction in total cardiomyocyte number in α-myosin heavy chain (MHC)–survivin
−/−
mice was due to an ≈50% lower mitotic rate without increased apoptosis. This occurred at the expense of DNA accumulation because survivin-deficient cardiomyocytes displayed marked DNA polyploidy indicative of consecutive rounds of DNA replication without cell division. Survivin small interfering RNA knockdown in neonatal rat cardiomyocytes also led to polyploidization and cell cycle arrest without apoptosis. Adenoviral overexpression of survivin in cardiomyocytes inhibited doxorubicin-induced apoptosis, induced DNA synthesis, and promoted cell cycle progression. The phenotype of the αMHC-survivin
−/−
mice also allowed us to determine the minimum cardiomyocyte number sufficient for normal cardiac function. In human cardiomyopathy, survivin was potently induced in the failing heart and downregulated again after hemodynamic support by a left ventricular assist device. Its expression positively correlated with the mean cardiomyocyte DNA content.

Conclusions—

We suggest that the ontogenetically determined cardiomyocyte number may be an independent factor in the susceptibility to cardiac diseases. Through its profound impact on both cardiomyocyte replication and apoptosis, survivin may emerge as a promising new target for myocardial regeneration.
Novel Use of Kaplan–Meier Methods to Explain Age and Gender Differences in Hypertension Control Rates
Authors: Bailey Kent R. , Grossardt Brandon R. , Graves John W.
Published: March 2008

Despite 40 years of research demonstrating the efficacy of antihypertensive medications for lowering blood pressure and decreasing cardiovascular disease, hypertension control rates worldwide remain low. We explored here how both medication efficacy rates and patient/physician decision-making (discontinuation rates) affect overall hypertension control rates. To do this we introduced the use of Kaplan–Meier methodology to predict hypertension control rates separately within age strata. An important aspect of our analysis is the use of a “treatment intensity score,” including both the number of agent(s) and the percentage of maximal dose of agent(s). We investigated how blood pressure control rates vary with age, gender, and treatment intensity. Our analysis found that both efficacy and discontinuation rates at different treatment intensities vary with age and gender, so that for each increase in age by 1 decade, the log hazard of achieving controlled blood pressure at any given intensity decreases by 0.10 in men and 0.20 in women. Overall hypertension control rates ranged from 80.8% for persons age 15 to 39 years to only 42.1% for persons age ≥80 years. Our analysis more accurately represents achievable hypertension control rates, with differences by gender, than previous work, because we investigated the contributions of efficacy and treatment aggressiveness in the control of hypertension.
V-like Formations in Flocks of Artificial Birds
Authors: Nathan Andre , Barbosa Valmir C.
Published: March 2008

We consider flocks of artificial birds and study the emergence of V-like formations during flight. We introduce a small set of fully distributed positioning rules to guide the birds' movements and demonstrate, by means of simulations, that they tend to lead to stabilization into several of the well-known V-like formations that have been observed in nature. We also provide quantitative indicators that we believe are closely related to achieving V-like formations, and study their behavior over a large set of independent simulations.
Consular Assistance and Protection: An EU Perspective
Authors: Porzio Giorgio
Published: March 2008

Article 20 (EC) is the first tangible expression of EU citizenship. By developing 'universal' consular protection, EU member states strive to reach two objectives: making sure that no one is left unprotected; and sharing the burden of assistance, especially in remote areas. This, however, is no easy feat, as member states are ultimately responsible for protecting and assisting their citizens. Recent events, such as the Indian Ocean tsunami or the mass evacuation from Lebanon, have proved that cooperation is the only way ahead, since no consular network can cope on its own with situations such as these. The question, then, is how to allow European consular cooperation to fulfil all of its promises without diminishing the effectiveness and perception of national responsibilities.
Preparation and Characterization of Electrospun SiO2 Nanofibers
Authors: Liu Yi , Sagi Sriramaraju , Chandrasekar Ramya , Zhang Lifeng , Hedin Nyle E. , Fong Hao
Published: March 2008

The objective of this study was to prepare and characterize electrospun SiO2 nanofibers for composite (particularly dental composite) applications. We investigated (1) tetraethyl orthosilicate (TEOS) as the alkoxide precursor, (2) polyethylene oxide (PEO) and polyvinyl pyrrolidone
(PVP) as the carrying polymers, (3) several solvents for making the spin dopes, and (4) the morphological and structural properties of the electrospun SiO2 nanofibers and their relationship with the pyrolysis temperatures. We also investigated the morphology durability of the prepared
SiO2 nanofibers by subjecting them to vigorous ultrasonic vibrations. The results indicated that the uniform (beads-free) amorphous SiO2 nanofibers with an average diameter of approximately 500 nm were successfully prepared. These SiO2 nanofibers also retained
their overall fiber morphology when subjected to vigorous ultrasonic vibrations. The electrospun SiO2 nanofibers were, therefore, nano-scaled glass (amorphous SiO2) fibers, and could be used for reinforcement of dental composites.
Phase and Shape Controlled Synthesis of CdS Nanocrystals and Their Characterization
Authors: Sadhu Suparna , Sen Tapasi , Patra Amitava
Published: March 2008

We demonstrated simple solution based methods for preparing CdS nanostructure materials with distinct and well-defined morphologies, including spherical, rod and tripod/tetrapod by varying the solvents. It is also found that solvent plays an important role on tuning the crystal structure
of nanocrystals, which is an important observation in this study. The mechanism related to crystal phase control is proposed and discussed. Our results reveal that the luminescence properties of CdS nanostructures depend on the size not on the shape of nanocrystals.
ZnO Hierarchical Nanostructures: Simple Solvothermal Synthesis and Growth Mechanism
Authors: Dev Apurba , Kar Soumitra , Chaudhuri Subhadra
Published: March 2008

Hierarchical nano/micro structures of ZnO have been fabricated by solvothermal approach on sol–gel derived ZnO thin films. Paintbrush like nano/micro rod assembly, double-sided brush and windmill type architectures of ZnO are obtained when the ZnO thin film coated substrates were
treated solvothermally in water at pH 10. Aligned nanorods are obtained at pH ∼ 13.5 in water. In ethylenediamine-water solvent divergent micro/nanorod assemblies such as hemispherical dandelion, rice plant type bush of ZnO are obtained. Increase in the percentage of ethyelendiamine resulted
in the formation of smaller assemblies of relatively thin nanorods. Initial slow reaction caused by the slow increase of the temperature inside the reaction medium and the different growth kinetics of the ZnO crystals are supposed to be the reason behind the architectural assemblies of the
ZnO crystals.
Size and Distribution: A Comparison of XRD, SAXS and SANS Study of II–VI Semiconductor Nanocrystals
Authors: Keshari Ashish K. , Pandey Avinash C.
Published: March 2008

The uniqueness of size dependent functional properties of II–VI semiconductor nanocrystals have led to the development of various techniques for determination of shape, size and distributions, although the accurate measurements of the particle sizes has always been a fundamental
task in nanoscience and even become more crucial with the discovery of quantum confinement effect. Acomparison of the well established techniques X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) with an emphasis on size and distribution
of the prepared samples are reported in order to elaborate more precise techniques for the analysis of particles sizes. Modified Scherrer formula for spherical particles has been used to calculate the particle sizes from XRD spectra. Analysis of SAXS data has been reported using Guinier model.
Small angle neutron scattering measurements has been performed for ZnO nanocrystals and the scattering data obtained is simulated for polydisperse sphere. The bare ZnO, ZnS and CdS and doped with Mn2+ systems are taken within the framework of our discussion. These materials were
synthesized by chemical precipitation route and found to have size distribution from 2 to 6 nm for spherical particles. Sizes determined from various techniques are in good agreement with each other however small angle scattering technique is more reliable than XRD to determine the sizes of
the nanoparticles.
Potential Vorticity (PV) Thinking in Operations: The Utility of Nonconservation
Authors: Brennan Michael J. , Lackmann Gary M. , Mahoney Kelly M.
Published: March 2008

The use of the potential vorticity (PV) framework by operational forecasters is advocated through case examples that demonstrate its utility for interpreting and evaluating numerical weather prediction (NWP) model output for weather systems characterized by strong latent heat release (LHR). The interpretation of the dynamical influence of LHR is straightforward in the PV framework; LHR can lead to the generation of lower-tropospheric cyclonic PV anomalies. These anomalies can be related to meteorological phenomena including extratropical cyclones and low-level jets (LLJs), which can impact lower-tropospheric moisture transport.

The nonconservation of PV in the presence of LHR results in a modification of the PV distribution that can be identified in NWP model output and evaluated through a comparison with observations and high-frequency gridded analyses. This methodology, along with the application of PV-based interpretation, can help forecasters identify aspects of NWP model solutions that are driven by LHR; such features are often characterized by increased uncertainty due to difficulties in model representation of precipitation amount and latent heating distributions, particularly for convective systems.

Misrepresentation of the intensity and/or distribution of LHR in NWP model forecasts can generate errors that propagate through the model solution with time, potentially degrading the representation of cyclones and LLJs in the model forecast. The PV framework provides human forecasters with a means to evaluate NWP model forecasts in a way that facilitates recognition of when and how value may be added by modifying NWP guidance. This utility is demonstrated in case examples of coastal extratropical cyclogenesis and LLJ enhancement. Information is provided regarding tools developed for applying PV-based techniques in an operational setting.
A Statistical Comparison of the Properties of Flash Flooding and Nonflooding Precipitation Events in Portions of New York and Pennsylvania
Authors: Jessup Stephen M. , DeGaetano Arthur T.
Published: March 2008

Flash floods reported for the forecast area of the National Weather Service Forecast Office at Binghamton, New York (BGM), are compared with similar significant precipitation and flash flood watch events not corresponding to flash flood reports. These event types are characterized by measures of surface hydrological conditions, surface and upper-air variables, thermodynamic properties, and proxies for synoptic-scale features. Flash flood and nonflood events are compared quantitatively via discriminant analysis and cross validation, and qualitatively via scatterplots and composite soundings. Results are presented in the context of a flash flood checklist used at BGM prior to this study. Flash floods and nonfloods are found to differ most significantly in antecedent soil moisture. The wind direction at 850 hPa shows differences between flood and nonflood events, with flooding more common for an easterly to southeasterly direction and nonflooding more common for a northwesterly direction. Southwesterly wind direction is characteristic of both types. In general, nonflooding significant precipitation events are more commonly associated with a better-defined ridge axis of relatively high 850-hPa equivalent potential temperature and larger convective available potential energy as compared to the flash flood events. Several parameters included on the BGM flash flood checklist, though effective at distinguishing significant precipitation events and flash floods from random events, were found to be unable to separate flash floods from nonflooding significant rain events.