bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecology of and control strategies for Calamagrostiscanadensis in boreal forest sites
Authors: Lieffers Victor J. , Macdonald S. Ellen , Hogg Edward H.
Published: July 2007

Calamagrostiscanadensis (Michx.) Beauv. is a widely distributed rhizomatous grass that can seriously inhibit growth of white spruce (Piceaglauca (Moench) Voss) seedlings in the boreal forests of North America. We review the dynamics of this grass during four successional stages: the colonization of disturbed sites; dominance of the site by the grass a few years after disturbance; gradual loss of dominance with overstory development; and maintenance of the grass at low levels in the understory of the mature forest. We also describe C. canadensis in relation to recruitment from clonal growth and seed, environmental conditions for growth, the effects of grass litter buildup on conifer seedling microclimate, and overall competitive abilities. Control strategies for C. canadensis are as follows. If the grass is found in nearly every square metre in the understory prior to logging, there will be rapid spread when the stand is clear-cut unless clones are killed using herbicides or a deep burn. Large spruce seedlings, planted on large soil scalps or mounds, coupled with release by way of herbicides or sheep grazing, may be necessary for plantation establishment under conditions of encroachment by C. canadensis. Alternatively, the shade provided by a partial canopy may inhibit the grass sufficiently to allow spruce seedlings to establish. If grass is not abundant in the understory, we recommend (i) minimizing forest floor disturbance to reduce sites for grass seedling colonization or (ii) a slash burn with the hope of encouraging colonization by herbaceous species that have less impact on conifer seedlings.
Ecological field theory model: a mechanistic approach to simulate plant–plant interactions in southeastern forest ecosystems
Authors: Mou Pu , Mitchell Robert J. , Jones Robert H.
Published: July 2007

Ecological field theory, unlike many other vegetation modeling approaches, provides a basis to construct an individually based, spatially explicit, and resource-mediated model for mechanistic simulation of plant–plant interactions and vegetation dynamics. The model REGROW has been developed, based on ecological field theory principles, to simulate vegetation dynamics for northern hardwood forests. Using data from a current study of a southern pine system to calibrate a modified version of this model, SPGROW, we simulated growth of individuals for the first growing season in stands of loblolly pine (Pinustaeda L.) and sweetgum (Liquidambarstyraciflua L.) seedlings and loblolly pine seedling–sweetgum sprout mixtures. SPGROW accurately simulated stand development at population and stand levels. However, less agreement occurred at the individual level between simulated and field survey values, possibly owing to lack of data on site heterogeneity and genetic variation. Plant interactions, which altered resource availability (light, water, and nutrients) to individual plants, played a major role in differentiating plant size in the model. Given its unique model structure and simulation accuracy, SPGROW has the potential to provide very detailed insight into the mechanisms of plant–plant interactions.
Site preparation burning to improve southern Appalachian pine–hardwood stands: aboveground biomass, forest floor mass, and nitrogen and carbon pools
Authors: Vose James M. , Swank Wayne T.
Published: July 2007

On three sites in the southern Appalachians, stands characterized by sparse overstories and dense Kalmialatifolia L. shrub layers were felled in early summer and burned in early fall. Amounts of aboveground vegetation and forest floor mass, nitrogen (N), and carbon (C) were measured before and after treatment by sampling wood, foliage, herbs, grasses, and forest floor (Oi and Oe + Oa layers). Burning decreased woody mass by 48 to 60% across the three sites. The most intense burn reduced mass from 180 to 70 Mg•ha−1, and N and C losses were 300 kg•ha−1 and 52 Mg•ha−1, respectively. Significant losses of mass, N, and C occurred in the Oi layer, but not in the Oe + Oa layer. Foliage, herbs, and grasses were totally consumed by the fires. Total aboveground N losses across sites ranged from 193 to 480 kg•ha−1. These losses may be significant because N availability is low on these sites. Variations in patterns of mass, N, and C consumption were related to differences in amounts, types, size distributions, and moisture contents of fuels.
Adoption of herbaceous weed control by southern forest industry
Authors: Teeter Lawrence , Bliss John C. , Henry William A.
Published: July 2007

Herbaceous weed control has been demonstrated to confer a significant growth advantage to southern pine plantations, thereby accelerating harvest schedules and enhancing the economic attractiveness of regeneration investments. Despite this attractiveness, previous research suggests that herbaceous weed control technology has been adopted by industries in the South on only a small portion of the potentially applicable area. This paper discusses the extent to which herbaceous weed control is being used by southern forest industries and identifies factors influencing its adoption. We hypothesize that a combination of more attractive alternative investment opportunities, environmental or legal concerns, perceived public concern over chemical use, and a planning cycle time lag may partially explain the apparently slow rate of herbaceous weed control adoption. The study data comprise results from a mail survey of industrial herbaceous weed control users in the South.
Estimating coefficients of base-age-invariant site index equations
Authors: Cao Quang V.
Published: July 2007

Remeasurement height data used in this study were collected from plantations of loblolly pine (Pinustaeda L.) established in the Southwide Pine Seed Source Study. Three different methods for estimating coefficients of five base-age-invariant site index models were evaluated. The first method involves obtaining coefficients from either a height–age equation or a differential equation. Coefficients from the remaining two methods were estimated from a height growth equation (difference equation) of which the dependent variable is either stand height or logarithm of height. Statistics used in the evaluation were mean of the differences (between the observed and predicted stand heights), mean of the absolute differences, and square root of mean squared error. Results indicated that in most cases, coefficients of the site index models evaluated should be obtained from the height growth equation.
Etiology of sugar maple decline in four Pennsylvania stands
Authors: Kolb T.E. , McCormick L.H.
Published: July 2007

Tree-ring analysis was used to study historical patterns of basal area increment (BAI) by healthy (0–5% dieback) and declined (greater than 30% dieback) overstory sugar maples (Acersaccharum Marsh.) in four stands in Pennsylvania. The objectives were to establish if and when BAI decreased in healthy and declined trees and to identify causal factors associated with decreased BAI. Reduction in BAI of declined compared with healthy trees was first evident following a series of defoliations and summer droughts in the mid-1960s and early 1970s. These stresses were followed by repeated damage by pear thrips (Taeniothripsinconsequens Uzel) in the 1980s and a drought in 1988, during which large reductions in BAI occurred for both declined and healthy trees in all stands. Foliar nutrient analysis of two stands suggested deficiency of Mg and Ca. Other factors hypothesized to be associated with this sugar maple decline as either predisposing or inciting factors include unusually warm winter temperatures in the 1980s and air pollution.
Photoperiod influences dehardening of Chamaecyparisnootkatensis seedlings
Authors: Hawkins B.J. , McDonald S.E.
Published: July 2007

In early January, seedlings of yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) were placed in controlled-environment chambers under constant, increasing, and decreasing photoperiods. Seedlings from all treatments were assessed for frost hardiness at 2-week intervals using the freeze-induced electrolyte leakage method. Seedlings subject to increasing day lengths began to deharden immediately and at a greater rate than seedlings under a constant photoperiod. Seedlings in the decreasing photoperiod treatment maintained maximum hardiness for 42 days and then began to deharden spontaneously, although photoperiod continued to decrease. Once dehardening began in this treatment, it proceeded at the fastest rate of all treatments. These results indicate that photoperiod has a significant influence on the initiation and rate of dehardening in yellow cypress, and maximum hardiness cannot be maintained indefinitely.
Response of woody eastern Canadian forest weeds to fall foliar treatments of glyphosate and triclopyr herbicides
Authors: Pitt D.G. , Thompson D.G. , Payne N.J. , Kettela E.G.
Published: July 2007

Second-season post-treatment efficacy data are presented for a New Brunswick field study comparing three formulations of glyphosate (VISION®, MON14420, and TOUCHDOWN®) and a single formulation of triclopyr (RELEASE®). Five rates of each herbicide were broadcast applied to a 2-year-old clearcut in early September. Two growing seasons after treatment, percent control values (based on total woody crown area) ranged from 21% at glyphosate rates < 0.25 × label maximum to more than 80% at rates ≥ 0.75 × label maximum. Coefficients of variation for percent control values decreased from 104% at the lower glyphosate rates to 9% at the higher rates. Total woody control provided by triclopyr was generally equivalent to that of glyphosate at rates < 0.5 × label maximum. Beyond this rate, percent control values for triclopyr averaged only 59% and coefficients of variation remained high (40%). At the individual-species level, the three glyphosate formulations provided greater crown volume reduction than triclopyr for white ash (Fraxinusamericana L.), beech (Fagusgrandifolia Ehrh.), hazel (Coryluscornuta Marsh.), and sugar maple (Acersaccharum Marsh.). Control of mountain maple (Acerspicatum Lam.) by TOUCHDOWN® was found to be slightly inferior to that of the other two glyphosate formulations. Control of elderberry (Sambucuspubens Michx.) by MON14420 was inferior to that of the other three herbicides. Nonlinear regression curves relating second-season control and herbicide dose are presented as a guide for silvicultural use.
LATTICE BOLTZMANN SIMULATION OF A NON-NEWTONIAN OSCILLATING FLOW IN A HIGH-FREQUENCY LIMIT
Authors: COLOSQUI CARLOS E. , YAKHOT VICTOR
Published: July 2007

The Lattice Boltzmann simulation of a flow generated by an oscillating plate is conducted in a wide range of frequency variation 0 < ωτ < ∞. The theoretically predicted transition from the viscoelastic (ωτ ≪ 1) Newtonian behavior to purely elastic non-Newtonian regime (ωτ ≫ 1) has been demonstrated. The relation of the derived solutions to microfluidics (high-frequency micro-resonators) is shown on an example of a "plane oscillator".
FROM THE BOLTZMANN TO THE LATTICE-BOLTZMANN EQUATION: BEYOND BGK COLLISION MODELS
Authors: PHILIPPI PAULO CESAR , HEGELE LUIZ ADOLFO , SURMAS RODRIGO , SIEBERT DIOGO NARDELLI , DOS SANTOS LUÍS ORLANDO EMERICH
Published: July 2007

In this work, we present a derivation for the lattice-Boltzmann equation directly from the linearized Boltzmann equation, combining the following main features: multiple relaxation times and thermodynamic consistency in the description of non isothermal compressible flows. The method presented here is based on the discretization of increasingly order kinetic models of the Boltzmann equation. Following a Gross-Jackson procedure, the linearized collision term is developed in Hermite polynomial tensors and the resulting infinite series is diagonalized after a chosen integer N, establishing the order of approximation of the collision term. The velocity space is discretized, in accordance with a quadrature method based on prescribed abscissas (Philippi et al., Phys. Rev E 73, 056702, 2006). The problem of describing the energy transfer is discussed, in relation with the order of approximation of a two relaxation-times lattice Boltzmann model. The velocity-step, temperature-step and the shock tube problems are investigated, adopting lattices with 37, 53 and 81 velocities.
LATTICE BOLTZMANN SIMULATIONS OF CONTACT LINE PINNING
Authors: JIA XINLI , MCLAUGHLIN J. B. , AHMADI G. , KONTOMARIS K.
Published: July 2007

Contact angle hysteresis is caused by contact line pinning by geometrical and/or chemical non-uniformities on a solid surface. For small contact angles, theories have been developed for the pinning of contact angles, and an analogy between geometrical and chemical defects has been established. This paper presents LBM results for the interaction of a contact line with a spatially periodic array of chemical defects. The results are for finite contact angles. Qualitative comparisons with existing theories for chemical defects and experimental results for geometrical defects are made for pinned contact lines.
SIMULATING TIME HARMONIC FLOWS WITH THE REGULARIZED L-BGK METHOD
Authors: AXNER LILIT , LATT JONAS , HOEKSTRA ALFONS G. , CHOPARD BASTIEN , SLOOT PETER M. A.
Published: July 2007

A recent improvement of the lattice BGK model, based on a regularization of the precollision distribution function, is applied to three dimensional Womersley flow. The accuracy and the stability of the model are essentially improved by using this regularization. A good agreement with analytical Womersley solution is presented, as well as an improvement of the accuracy over standard L-BGK. Numerical stability of the scheme for a range of Reynolds and Womersley numbers is also presented, demonstrating an enhancement of the stability range of L-BGK for this type of flows.
LATTICE BOLTZMANN MODELING OF THROMBOSIS IN GIANT ANEURYSMS
Authors: CHOPARD B. , OUARED R. , RUEFENACHT D. A. , YILMAZ H.
Published: July 2007

We propose a numerical model of blood flow and blood clotting whose purpose is to describe thrombus formation in cerebral aneurysms. We identify possible mechanisms that can cause occurence of spontaneous thrombosis in unruptured giant intracranial aneurysms. Our main claim is that, under normal conditions, there is a low shear rate threshold below which thrombosis starts and growths. This assumption is supported by several evidences from literature. The proposed mechanisms are incorporated into a Lattice Boltzmann (LB) model for blood flow and platelets adhesion and aggregation. Numerical simulations show that the low shear rate threshold assumption together with aneurysm geometry account well for the observations.
THE EXACT EIGENSTATES OF THE NEUTRINO MASS MATRIX WITHOUT CP-PHASE VIOLATION
Authors: PALCU ADRIAN
Published: July 2007

In this paper we obtain the exact mass-eigenstates of the Majorana physical neutrinos. We start by taking into account a general 3 × 3 mass matrix (ignoring any CP-phase violation). It is then diagonalized by exactly solving an appropriate set of equations. The solution provides straightforwardly the mass eigenvalues depending on the diagonal entries and mixing angles. Finally, the consequences of these analytical expressions are discussed assuming certain restrictions such as the global lepton number L = Le- Lμ- Lτ(rigorously conserved or softly broken) and the μ - τ interchange symmetry. The minimal absolute mass in the neutrino sector is also obtained since the two plausible scenarios invoked above are employed.
AN EMPIRICAL STUDY OF QUERY EFFECTIVENESS IMPROVEMENT VIA MULTIPLE VISUAL FEATURE INTEGRATION
Authors: SHEN JIALIE , SHEPHERD JOHN , NGU ANNE H. H.
Published: July 2007

This article is a comprehensive evaluation of a new framework for indexing image data, called CMVF, which can combine multiple data properties with a hybrid architecture. The goal of this system is to allow straightforward incorporation of multiple visual feature vectors, based on properties such as color, texture and shape, into a single low-dimension vector that is more effective for retrieval than the larger individual feature vectors. Moreover, CMVF is not only constrained to visual properties, but can also incorporate human classification criteria to further strengthen image retrieval process. The controlled study present in this paper concentrates on CMVF's performance on images, examining how the incorporation of extra features into the indexing affects both efficiency and effectiveness. Analysis and empirical evidence suggest that the inclusion of extra visual features can significantly improve system performance. Furthermore, it demonstrated that CMVF's effectiveness is robust against various kinds of common image distortions and initial (random) configuration of neural network.
HETEs enhance IL-1-mediated COX-2 expression via augmentation of message stability in human colonic myofibroblasts
Authors: Di Mari J. F. , Saada J. I. , Mifflin R. C. , Valentich J. D. , Powell D. W.
Published: July 2007

Proinflammatory cytokines and eicosanoids are central players in intestinal inflammation. IL-1, a key cytokine associated with intestinal mucosal inflammation, induces COX-2 expression in human colonic myofibroblasts (CMF) and increased prostaglandin E2secretion is associated with inflammatory bowel disease (IBD) and colorectal cancer (CRC). We have previously demonstrated that IL-1α-induced cyclooxygenase-2 (COX-2) expression is the result of NF-κB- and ERK-mediated transcription, as well as COX-2 message stabilization, which depends on p38, MAPKAPK-2 (MK-2) and human antigen R (HuR) RNA binding protein activation. Lipoxygenase (LOX)-derived hydroxyeicosatetraenoic acids (HETEs) are elevated in IBD and colonic adenomas and “cross talk” has been observed between the COX and LOX pathways. Since COX-2 expression is primarily in CMFs in colonic adenomas, we examined the impact of LOX metabolites, particularly HETEs, on IL-1α-induced COX-2 expression in human CMFs. Although 5(S)-, 12(R)-, and 15(S)-HETEs alone had little to no effect on COX-2 expression, they enhanced IL-1-mediated COX-2 expression 3.6 ± 0.5-fold. Studies utilizing heterogeneous nuclear RNA amplification and 5,6-dichloro-β-d-ribofuranosylbenzimidazole treatment were undertaken to measure COX-2 transcription and message stabilization, respectively. We found that HETEs enhanced IL-1-induced COX-2 mRNA levels in CMF as the result of increased p38, MK-2, and HuR activity, increasing message stability greater than that observed with IL-1 alone. Thus HETEs can act synergistically with IL-1α to induce COX-2 expression in human CMFs. HETEs may play a role in both colonic inflammation and in increasing the risk of CRC in IBD independently and via induction of COX-2-mediated prostaglandin secretion.
PGE2inhibits apoptosis in human adenocarcinoma Caco-2 cell line through Ras-PI3K association and cAMP-dependent kinase A activation
Authors: Leone Vincenza , di Palma Antonella , Ricchi Paolo , Acquaviva Fabio , Giannouli Maria , Di Prisco Anna Maria , Iuliano Francesca , Acquaviva Angela M.
Published: July 2007

PGE2plays a critical role in colorectal carcinogenesis. We have previously shown that COX-2 expression and PGE2synthesis are mediated by IGF-II/IGF-I receptor signaling in the Caco-2 cell line and that the pathway of phosphatidylinositol 3-kinase (PI3K)/Akt protects the cell from apoptosis. In the present study, we demonstrate that PGE2has the ability to increase Ras and PI3K association and decrease the level of apoptosis in the same experimental system. The effect of PGE2on PI3K/Ras association is dependent on the activation of EP4 receptor, the increase of cAMP levels, and the activation of PKA. In fact, treatment of cells with the PKA inhibitor H89 decreases the association of Ras and PI3K and Ras-associated PI3K activity. PKA inhibitor H89 is able to decrease threonine phosphorylation of Akt and to increase serine phosphorylation of Akt by p38 MAPK and counteracts the cytoprotective effect induced by PGE2. In addition, PGE2is able to activate p38 MAPK and the inhibition of p38 MAPK, with SB203580 specific inhibitor or with dominant negative MKK6 kinase, is able to revert the apoptotic effect of H89 and serine phosphorylation of Akt. The effect of PGE2on Caco-2 cell survival through PKA activation is mediated and regulated by the balance of threonine/serine phosphorylation of Akt by p38 kinase and PI3K. In conclusion, our data elucidate a novel mechanism for regulation of colon cancer cell survival and provide evidences for new combinatory treatments of colon cancer.
NFKB1 promoter variation implicates shear-induced NOS3 gene expression and endothelial function in prehypertensives and stage I hypertensives
Authors: Park Joon-Young , Farrance Iain K. G. , Fenty Nicola M. , Hagberg James M. , Roth Stephen M. , Mosser David M. , Wang Min Qi , Jo HanJoong , Okazaki Toshihiko , Brant Steven R. , Brown Michael D.
Published: July 2007

In endothelial cells, NF-κB is an important intracellular signaling molecule by which changes in wall shear stress are transduced into the nucleus to initiate downstream endothelial nitric oxide synthase ( NOS3) gene expression. We investigated whether NF-κ light-chain gene enhancer in B cells 1 (NFKB1) promoter polymorphism (−94 NFKB1 I/D, where I is the insertion allele and D is the deletion allele) was associated with 1) NOS3 gene expression in endothelial cells under physiological levels of unidirectional laminar shear stress (LSS) and 2) endothelial function in prehypertensive and stage I hypertensive individuals before and after a 6-mo supervised endurance exercise intervention. Competitive EMSAs revealed that proteins present in the nuclei of endothelial cells preferentially bound to the I allele NFKB1 promoter compared with the D allele. Reporter gene assays showed that the I allele promoter had significantly higher activity than the D allele. In agreement with these observations, homozygous II genotype cells had higher p50 expression levels than homozygous DD genotype cells. Cells with the homozygous II genotype showed a greater increase in NOS3 protein expression than did homozygous DD genotype cells under LSS. Functional experiments on volunteers confirmed higher baseline reactive hyperemic forearm blood flow, and, furthermore, the subgroup analysis revealed that DD homozygotes were significantly less prevalent in the exercise responder group compared with II and ID genotypes. We conclude that the −94 NFKB1 I/D promoter variation contributes to the modulation of vascular function and adaptability to exercise-induced flow shear stress, most likely due to differences in NFKB1 gene transactivity.
Systemic hemodynamic and regional blood flow changes in response to chronic reductions in uterine perfusion pressure in pregnant rats
Authors: Sholook M. M. , Gilbert J. S. , Sedeek M. H. , Huang M. , Hester R. L. , Granger J. P.
Published: July 2007

Preeclampsia (PE) is associated with increased total peripheral resistance (TPR), reduced cardiac output (CO), and diminished uterine and placental blood flow. We have developed an animal model that employs chronic reductions in uterine perfusion pressure (RUPP) in pregnant rats to generate a “preeclamptic-like” state during late gestation that is characterized by hypertension, proteinuria, and endothelial dysfunction. Although this animal model has many characteristics of human PE, the systemic hemodynamic and regional changes in blood flow that occur in response to chronic RUPP remains unknown. Therefore, we hypothesized that RUPP would decrease uteroplacental blood flow and CO, and increase TPR. Mean arterial pressure (MAP), CO, cardiac index (CI), TPR, and regional blood flow to various tissues were measured using radiolabeled microspheres in the following two groups of conscious rats: normal pregnant rats (NP; n = 8) and RUPP rats ( n = 8). MAP was increased (132 ± 4 vs. 99 ± 3 mmHg) in the RUPP rats compared with the NP dams. The hypertension in RUPP rats was associated with increased TPR (2.15 ± 0.02 vs. 0.98 ± 0.08 mmHg·ml−1·min−1) and decreased CI (246 ± 20 vs. 348 ± 19 ml·min−1·kg−1, P < 0.002) when contrasted with NP dams. Furthermore, uterine (0.16 ± 0.03 vs. 0.38 ± 0.09 ml·min−1·g tissue−1 ) and placental blood flow (0.30 ± 0.08 vs. 0.70 ± 0.10 ml·min−1·g tissue−1) were decreased in RUPP compared with the NP dams. These data demonstrate that the RUPP model of pregnancy-induced hypertension has systemic hemodynamic and regional blood flow alterations that are strikingly similar to those observed in women with PE.
Effect of exercise duration on postprandial hypertriglyceridemia in men with metabolic syndrome
Authors: Zhang John Q. , Ji Lisa L. , Fogt Donovan L. , Fretwell Vicki S.
Published: July 2007

We examined the effect of exercise on postprandial hypertriglyceridemia (PHTG) and insulin resistance in individuals with metabolic syndrome. Subjects were 10 hypertriglyceridemic men with insulin resistance [age = 35.0 ± 1.8 yr, body weight = 90.7 ± 3.3 kg, fasting triglyceride (TG) = 2.6 ± 0.4 mmol/l, peak oxygen consumption (V̇o2peak) = 36.0 ± 1.3 ml−1·kg−1·min−1, and homeostatic model assessment of insulin resistance (HOMA-IR)= 3.1 ± 0.3]. Each participant performed a control trial (Ctr; no exercise) and three exercise trials at 60% of their V̇o2peakfor 30 min (30 min-Ex), 45 min (45 min-Ex) and 60 min (60 min-Ex). All subjects had a fat meal in each trial. In the exercise trials, the subject jogged on a treadmill for a designated duration of 12 h before ingestion of a fat meal. Blood samples were taken at 0 h (before the meal) and at 2, 4, 6, and 8 h after the meal. The plasma TG, area score under TG concentration curve over an 8-h period (TG AUC) after the meal, and HOMA-IR were analyzed. The TG AUC scores in both the 45 min-Ex and 60 min-Ex were 31 and 33% lower, respectively, than Ctr ( P < 0.02). There were no significant differences in TG AUC scores between the 30 min-Ex and the Ctr ( P > 0.05). There were no trial differences in the fasting plasma glucose concentration ( P > 0.05). HOMA-IR values in the 30 min-Ex, 45 min-Ex, and 60 min-Ex trials were lower than the Ctr ( P < 0.03), but no significant differences were found in HOMA-IR among the exercise trials. The results suggest that for physically inactive individuals with metabolic syndrome, exercising at moderate intensity for 45 min effectively attenuates PHTG while exercise for 30 min is sufficient to improve insulin action.
Familial aggregation of nasal conditioning capacity
Authors: Sahin-Yilmaz Asli , Pinto Jayant M. , de Tineo Marcy , Elwany Samy , Naclerio Robert M.
Published: July 2007

In our previous studies on nasal conditioning, we observed a large variability among individuals to condition inspired air. Although we previously investigated various physiological parameters (age, sex, nasal mucosal temperature, heart rate, blood pressure, and nasal volume) that might underlie these differences, we have been unable to explain this variability. Many proteins and molecules, which are under genetic control and could affect nasal conditioning, are involved in water transport,. In this study, we hypothesized that familial factors may contribute to the differences in nasal conditioning capacity (NCC). We performed a prospective study of 47 sibling pairs. Cold dry air was delivered to the nose, and the total water gradient (TWG) was calculated to determine the NCC. We found a highly significant intraclass correlation of 0.53 ( P < 0.0001) between sibling pairs for the TWG. These results suggest that there is a familial basis for nasal conditioning and a large enough genetic component to search for genes explaining the observed correlation.
Postactivation potentiation in a human muscle: effect on the load-velocity relation of tetanic and voluntary shortening contractions
Authors: Baudry Stéphane , Duchateau Jacques
Published: July 2007

Recently it was demonstrated that postactivation potentiation (PAP), which refers to the enhancement of the muscle twitch torque as a result of a prior conditioning contraction, increased the maximal rate of torque development of tetanic and voluntary isometric contractions ( 3 ). In this study, we investigated the effects of PAP and its decay over time on the load-velocity relation. To that purpose, angular velocity of thumb adduction in response to a single electrical stimulus (twitch), a high-frequency train of 15 pulses at 250 Hz (HFT250), and during ballistic voluntary shortening contractions, performed against loads ranging from 10 to 50% of the maximum torque, were recorded before and after a conditioning 6-s maximal voluntary contraction (MVC). The results showed an increase of the peak angular velocity for the different loads tested after the conditioning MVC ( P < 0.001), but the effect was greatest for the twitch (∼182%) compared with the HFT250 or voluntary contractions (∼14% for both contraction types). The maximal potentiation occurred immediately following the conditioning MVC for the twitch, whereas it was reached 1 min later for the tetanic and ballistic voluntary contractions. At that time, the load-velocity relation was significantly shifted upward, and the maximal power of the muscle was increased (∼13%; P < 0.001). Furthermore, the results also indicated that the effect of PAP on shortening contractions was not related to the modality of muscle activation. In conclusion, the findings suggest a functional significance of PAP in human movements by improving muscle performance of voluntary dynamic contractions.
Cardioprotective repair through stem cell-based cardiopoiesis
Authors: Behfar Atta , Terzic Andre
Published: July 2007

Ischemic heart disease continues to progress at pandemic levels despite current preventive and therapeutic interventions. Recent advances in stem cell biology have provided the impetus for a paradigm shift in treatment options, potentially transforming palliative care into curative therapy. Although delivery of stem cells in clinical trials has resulted in a modest functional improvement of myocardial performance in the setting of infarction, ongoing efforts at the bench and bedside are taking place to increase stem cell propensity for engraftment and homing into diseased myocardium. The newest opportunity has arisen with the delivery of stem cells guided to execute the cardiac program. Here, we examine the recent application of genomic and proteomic technology to decipher the process of cardiopoiesis and to recruit cardiopoietic stem cells for cardioprotection and safe myocardial repair.
Hypersensitivity of BK
Ca
to Ca
2+
Sparks Underlies Hyporeactivity of Arterial Smooth Muscle in Shock
Authors: Zhao Guiling , Zhao Yan , Pan Bingxing , Liu Jie , Huang Xuliang , Zhang Xiuqin , Cao Chunmei , Hou Ning , Wu Caihong , Zhao Ke-seng , Cheng Heping
Published: July 2007

Large conductance Ca
2+
-activated K
+
channels (BK
Ca
) play a critical role in blood pressure regulation by tuning the vascular smooth muscle tone, and hyposensitivity of BK
Ca
to Ca
2+
sparks resulting from its altered β1 subunit stoichiometry underlies vasoconstriction in animal models of hypertension. Here we demonstrate hypersensitivity of BK
Ca
to Ca
2+
sparks that contributes to hypotension and blunted vasoreactivity in acute hemorrhagic shock. In arterial smooth muscle cells under voltage-clamp conditions (0 mV), the amplitude and duration, but not the frequency, of spontaneous transient outward currents of BK
Ca
origin were markedly enhanced in hemorrhagic shock, resulting in a 265% greater hyperpolarizing current. Concomitantly, subsurface Ca
2+
spark frequency was either unaltered (at 0 mV) or decreased in hyperpolarized resting cells. Examining the relationship between spark and spontaneous transient outward current amplitudes revealed a hypersensitive BK
Ca
activity to Ca
2+
spark in hemorrhagic shock, whereas the spark–spontaneous transient outward current coupling fidelity was near unity in both groups. Importantly, we found an acute upregulation of the β1 subunit of the channel, and single-channel recording substantiated BK
Ca
hypersensitivity at micromolar Ca
2+
, which promotes the α and β1 subunit interaction. Treatment of shock animals with the BK
Ca
inhibitors iberiotoxin and charybdotoxin partially restored vascular membrane potential and vasoreactivity to norepinephrine and blood reinfusion. Thus, the results underscore a dynamic regulation of the BK
Ca
–Ca
2+
spark coupling and its therapeutic potential in hemorrhagic shock–associated vascular disorders.
Parents View a Brief Violence Prevention Program in Clinic
Authors: Scholer Seth J. , Mukherjee Anamika B. , Gibbs Kirsten I. , Memon Shafia , Jongeward Kathryn L.
Published: July 2007

Participants were parents of 1- to 7-year-old children presenting to a pediatric clinic. The intervention was Play Nicely, 2nd edition, a multimedia educational program that teaches childhood aggression management skills. On average, parents viewed 10 to 15 min in clinic. The average age of the 89 participants was 30 years; 49% were African American, 29% were married, and 12% had a college education. Preintervention, 90% of parents stated that they felt very comfortable managing aggression. Postintervention, 90% of parents planned to change how they discipline their own child. More than 90% had at least one positive comment about the program; there were no negative comments. A brief intervention that addresses childhood aggression is embraced by a relatively diverse group of parents who viewed it during their children's primary care visit. Parents' prior comfort level with managing aggression should not be used to screen who might benefit. The program has implications for violence prevention.
Lymphedema of the Lower Extremity: Is It Genetic or Nongenetic?
Authors: Shinawi Marwan
Published: July 2007

Lymphedema of the lower extremities is a diagnostic challenge. Exclusion of secondary causes of limb swelling and secondary lymphedema is the initial step. Primary lymphedema is classified into idiopathic and familial (hereditary) subgroups. Hereditary lymphedema can be nonsyndromic or associated with congenital anomalies or with abnormal physical findings. A 13-year-old girl presented with unilateral lower extremity lymphedema. Her medical and family history was unremarkable. The physical examination was negative for dysmorphic features and congenital anomalies. Lymphoscintigraphy showed no evidence of lymph flow in the left lower extremity, which persisted at the delayed 2-hour image. A comprehensive clinical and family history that includes a thorough physical examination are the mainstays of the medical assessment of lymphedema in children. Isotopic lymphoscintigraphy is generally considered the gold standard for confirmation of the diagnosis. This article discusses the differential diagnosis, reviews the literature, and suggests a simplified and an updated flowchart for the classification of unilateral limb lymphedema in children.
Guest Satisfaction and Restaurant Performance
Authors: Gupta Sachin , McLaughlin Edward , Gomez Miguel
Published: July 2007

This study demonstrates a methodology to quantify the links between customer satisfaction, repeat-purchase intentions, and restaurant performance. Using data from a national restaurant chain, the authors constructed a series of mathematical models that predict how the level of customer satisfaction with certain attributes of guests' dining experience affects the likelihood that they will come back. In turn, the model shows how guests' “comeback” scores and other variables affect restaurant performance (i.e., sales and entrée counts). Robust and statistically significant, the models showed that restaurants that pay attention to food quality, appropriate cost, and attentive service have the greatest chance to increase guests' intent to return. In turn, that intent to return is a chief driver of increased sales.
Driving Demand for the Quarterdeck
Authors: Kwortnik Robert J. , Vosburgh James
Published: July 2007

The Quarterdeck Beachside Villas and Grill is a small property that faces an all too common set of challenges, most of them stemming from steep seasonality. Located on Nova Scotia's south shore, the Quarterdeck sells out during the summer months but is nearly empty during the winter. This case study examines the Quarterdeck's marketing approach and outlines strategies for driving off-season demand by focusing specifically on identifying guests' needs and desires to develop new product bundles and marketing communications. Although these ideas emerge from the Quarterdeck's particular circumstances, the strategies are applicable to many small hospitality companies that face seasonal demand.
The Effect of Meal Pace on Customer Satisfaction
Authors: Noone Breffni M. , Kimes Sheryl E. , Mattila Anna S. , Wirtz Jochen
Published: July 2007

Restaurant operators who seek to increase table turns during peak periods may want to speed up the meal's pace. However, excessive speed may make customers feel rushed. A survey of 218 respondents found that too fast a pace does affect customer satisfaction with the meal experience, with fine-dining customers more sensitive to pacing issues than customers in casual or upscale casual restaurants. Regardless of restaurant type, too fast a pace during the meal itself diminishes customer satisfaction, but speed during check settlement is often appreciated. The effects on customer satisfaction of the pace of welcome, seating, and taking drink orders depend partly on the type of restaurant and on the meal type. Guests at fine-dining restaurants do not want these preprocess events to be rushed. Additionally, a faster pace during these preprocess events at dinner diminished satisfaction ratings as compared to lunch.
Pseudo-admittance Bilateral Telemanipulation with Guidance Virtual Fixtures
Authors: Abbott Jake J. , Okamura Allison M.
Published: July 2007

Pseudo-admittance is introduced as a novel bilateral telemanipulation system that is designed to mimic proportional-velocity admittance control on systems where the master is an impedance-type robot. The controller generalizes to systems with slave robots of the impedance or admittance type. Pseudo-admittance uses a proxy with admittance dynamics combined with direct force feedback from the slave, resulting in unique properties that mimic admittance control and exhibit tremor attenuation and quasi-static transparency. Pseudo-admittance control has potential benefits for tasks that require better-than-human levels of precision, as well as with systems that are typically run under rate control. The controller can also be modified to include virtual fixtures that provide guidance during task execution, while leaving ultimate control of the system with the operator. Guidance virtual fixtures could be used as macros that increase both speed and precision on structured tasks that require direct human control. The properties of the system are verified through simulations and experiments.
Radiographic Findings in the Shoulder and Elbow of Major League Baseball Pitchers
Authors: Wright Rick W. , Steger-May Karen , Klein Sandra E.
Published: July 2007

Background

Changes in the dominant shoulder and elbow of professional pitchers have been noted on radiographs, magnetic resonance imaging scans, and ultrasound studies. The relationship of these findings to future injury and to time lost from play has not been identified.

Hypothesis

Degenerative changes of the shoulder and elbow are common findings on the radiographs of asymptomatic Major League Baseball pitchers. The changes are cumulative with increased pitching. These findings are not predictive of time on the disabled list.

Study Design

Cohort study (prognosis); Level of evidence, 4.

Methods

Fifty-seven asymptomatic Major League Baseball pitchers participating in the St Louis Cardinals spring training camp underwent routine preseason radiographic screening of their dominant shoulder and elbow between 1986 and 1998. Radiographs were reviewed for osteophytes, cystic changes, joint-space narrowing, and loose bodies. All findings were recorded as present or absent. Public baseball records were reviewed for arm dominance, age, years of professional pitching, professional innings pitched, shoulder or elbow injury or surgery, and time on the disabled list. These factors were statistically evaluated for their possible association with findings seen on preseason radiographs.

Results

Shoulder radiographs were available for 57 pitchers, and elbow radiographs were available for 56 pitchers. Both groups had an average age of 29 years. The average number of radiographic findings was 3 for the shoulder and 7 for the elbow. Comparing pitchers on the disabled list for a shoulder or elbow injury with those not on the disabled list demonstrated no significant difference in the age, number of seasons pitched, or number of innings pitched between the 2 groups. When individual radiographic findings were compared, no single finding was predictive of disabled list status (P > .05 in all cases). The sum of radiographic findings for the shoulder was significantly correlated with the number of innings pitched in professional baseball (Pearson correlation coefficient, 0.46; P = .0004). The elbow data showed a similar correlation (Pearson correlation coefficient, 0.38; P = .003). When select individual radiographic findings were evaluated for an association with the number of innings pitched, the presence of acromioclavicular joint findings in the shoulder and radial head osteophytes and radioulnar joint findings in the elbow increased with an increase in innings pitched (P < .05).

Conclusion

Professional pitchers develop degenerative changes over time in both the shoulder and elbow of their dominant (pitching) arm due to chronic repetitive stresses placed across the joints. These findings do not predict time spent on the Major League Baseball disabled list.
Importance of Tibial Slope for Stability of the Posterior Cruciate Ligament—Deficient Knee
Authors: Giffin J. Robert , Stabile Kathryne J. , Zantop Thore , Vogrin Tracy M. , Woo Savio L-Y. , Harner Christopher D.
Published: July 2007

Background

Previous studies have shown that increasing tibial slope can shift the resting position of the tibia anteriorly. As a result, sagittal osteotomies that alter slope have recently been proposed for treatment of posterior cruciate ligament (PCL) injuries.

Hypotheses

Increasing tibial slope with an osteotomy shifts the resting position anteriorly in a PCL-deficient knee, thereby partially reducing the posterior tibial “sag” associated with PCL injury. This shift in resting position from the increased slope causes a decrease in posterior tibial translation compared with the PCL-deficient knee in response to posterior tibial and axial compressive loads.

Study Design

Controlled laboratory study.

Methods

Three knee conditions were tested with a robotic universal force-moment sensor testing system: intact, PCL-deficient, and PCL-deficient with increased tibial slope. Tibial slope was increased via a 5-mm anterior opening wedge osteotomy. Three external loading conditions were applied to each knee condition at 0°, 30°, 60°, 90°, and 120° of knee flexion: (1) 134-N anterior-posterior (A-P) tibial load, (2) 200-N axial compressive load, and (3) combined 134-N A-P and 200-N axial loads. For each loading condition, kinematics of the intact knee were recorded for the remaining 5 degrees of freedom (ie, A-P, medial-lateral, and proximal-distal translations, internal-external and varus-valgus rotations).

Results

Posterior cruciate ligament deficiency resulted in a posterior shift of the tibial resting position to 8.4 ± 2.6 mm at 90° compared with the intact knee. After osteotomy, tibial slope increased from 9.2° ± 1.0° in the intact knee to 13.8° ± 0.9°. This increase in slope reduced the posterior sag of the PCL-deficient knee, shifting the resting position anteriorly to 4.0 ± 2.0 mm at 90°. Under a 200-N axial compressive load with the osteotomy, an additional increase in anterior tibial translation to 2.7 ± 1.7 mm at 30° was observed. Under a 134-N A-P load, the osteotomy did not significantly affect total A-P translation when compared with the PCL-deficient knee. However, because of the anterior shift in resting position, there was a relative decrease in posterior tibial translation and increase in anterior tibial translation.

Conclusion

Increasing tibial slope in a PCL-deficient knee reduces tibial sag by shifting the resting position of the tibia anteriorly. This sag is even further reduced when the knee is subjected to axial compressive loads.

Clinical Relevance

These data suggest that increasing tibial slope may be beneficial for patients with PCL-deficient knees.
“Do What I Do” and “Do How I Do”: Different Components of Imitative Learning Are Mediated by Different Neural Structures
Authors: Petrosini Laura
Published: July 2007

The involvement of different neural structures in imitative learning was studied in two paradigms. In an experimental paradigm, rats observed actor rats learning spatial procedures in a water maze. After the observational training, the observers underwent a cerebellar lesion, preventing further procedural acquisitions, and then were tested in the water maze previously observed. The cerebellar networks appear to be indispensable for acquiring by imitation the spatial procedures. The procedural sequence was then dissected into the single behavioral units, demonstrating that such units do exist and can be independently acquired. By using repetitive transcranial magnetic stimulation (rTMS), the role of the cerebellum and prefrontal cortex in imitative learning was investigated in humans. Subjects observed an actor detecting a hidden sequence in a matrix and then performed the task detecting either the previously observed sequence or a new one. Cerebellar rTMS applied before the observational training interfered with performance of the new sequence, whereas prefrontal rTMS interfered also with performance of the previously observed one. rTMS delivered after the observational training did not influence task execution. These findings indicate that the cerebellum and prefrontal cortex interact in planning actions, the former by permitting the acquisition by imitation of procedural competencies and the latter by providing flexibility among already acquired solutions. NEUROSCIENTIST 13(4):335—348, 2007. DOI: 10.1177/1073858407300687
Develop A Seamless Individualized Pressure Ulcer Care Plan: Recognize–Understand–Solve
Authors: Spahn James G.
Published: July 2007

The prevalence of pressure ulcers in patients has been recognized as a quality of care indicator. The suffering and expense resulting from this mostly preventable condition requires a more aggressive approach to both the prevention and treatment of pressure ulcers. Government regulations require planning for the next level of care for the at-risk patient in a clinically and financially effective manner.
School-Based HIV/STD Prevention Programs
Authors: Ateka Givans K. , Lairson David R.
Published: July 2007

Objective: To evaluate the City of Houston HIV/STD Prevention program in public high schools using the cost−utility-analysis approach. Methods: The study design was cross-sectional, comparing students who had undertaken the program with those who had not, and was based on a range of variables. Data on reported sexual behavior were used in a model for estimating the probability of HIV infection. The difference between the intervention and comparison group participants in the probability of infection was the basis for estimating program effects in terms of averted HIV infections. Program costs were obtained from the city of Houston Department of Health and Human Services (DHHS). Scenario-based cost−utility-ratios were computed based on costs and effects. Results: The program was cost-saving for female and cost-effective for male participants when ethnicity adjusted HIV prevalence was used with the assumption of best case scenario. It remained cost-effective for female but not for male participants in the base case scenario. Using the unadjusted HIV prevalence, the program was only cost-effective for female participants in the best case scenario. Conclusion: The program achieved significant risk reduction in HIV infection, particularly among female participants, on a relatively low budget.