bluuebunny/crossref_metadata_2025 huggingface dataset:
Host selection and responses to forest fragmentation in acorn weevils: inferences from dynamic occupancy models
Authors: Govindan Byju N. , Kéry Marc , Swihart Robert K.
Published: November 2011

Prior studies on species‐specific responses to habitat alteration have demonstrated that niche breadth is positively associated with patch occupancy rates in landscapes fragmented by agriculture. However, these studies generally have focused on vertebrates and relied upon data collected at a single point in time, neglecting dynamic processes that could alter inferences. We studied the effects of host selection and forest fragmentation on population dynamics of acorn weevils Curculio, the primary insect seed predators of oaks in North America. Detection/non‐detection data were collected from 174 red and white oaks in 19 forested fragments from 2005–2008. We used dynamic multi‐season site‐occupancy models within a Bayesian framework to explore variation in patch (tree‐level) occupancy dynamics of three species of weevils that vary in their specialization, i.e. their relative selection of red and white oak as hosts: C. pardalis (white oak specialist), C. sulcatulus (generalist) and C. proboscideus (generalist). Contrary to expectations, the specialist exhibited greater estimated rates of occupancy than generalists. However, red oak trees occupied by the white oak specialist appeared to function as sink populations maintained by frequent colonization following local extinction. Specialists also exhibited greater relative variation in occupancy and relative abundance on their host trees among years. Generalists exhibited lower local extinction and colonization rates than the specialist. Occupancy and vital rates of weevils on a host tree increased with acorn production and were significantly influenced by neighborhood forest density. Our results suggest that across much of their range in the eastern United States acorn weevils exist in fragmented, temporally dynamic landscapes, with generalists occurring on a lower proportion of usable trees but buffered by access to more suitable patches and greater patch‐specific survival. More generally, our results demonstrate that estimates of specialization derived from occupancy data may be misleading in the absence of patch‐specific information on vital rates.
Seed traits, seed‐reserve utilization and offspring performance across pre‐industrial to future CO2 concentrations in a Mediterranean community
Authors: Grünzweig José M. , Dumbur Rita
Published: November 2011

Atmospheric CO2 enrichment can affect plants directly via impacts on their performance, and indirectly, by environment‐specific traits passed down from the mother plant to the offspring. Such maternal effects can significantly alter plant species composition, especially in annual ecosystems where the entire community is recruited from seeds each year. This study assessed impacts of future, high CO2 (440 and 600 ppm) and pre‐industrial, low CO2 (280 ppm) on seed traits and offspring performance in three plant functional groups (grasses, legumes, forbs) comprising 17 annual species of a semi‐arid Mediterranean community. In grasses, seed size and seed‐reserve utilization as expressed by root elongation tended to be higher at high than at low maternal CO2, but total seed protein concentration and protein pool decreased with increasing maternal CO2. The response of seed size to high CO2 increased with increasing leaf‐mass fraction in grasses, and decreased with decreasing concentration of leaf non‐structural carbohydrates in legumes. Offspring development was studied at ambient CO2, and showed reduced emergence success of high‐CO2 progeny compared with low‐CO2 progeny in forbs. Total biomass was lower in high‐CO2 than in low‐CO2 offspring across all functional groups. The biomass response to high maternal CO2 in legume offspring correlated inversely with seed size, resulting in up to 25% lower biomass in large‐seeded species. Under the scenario of maternal effects combined with projected changes in biomass and seed production under direct exposure to high CO2, legumes might gain and forbs and grasses might lose from future CO2 enrichment. Most changes in seed traits and offspring performance were greater between pre‐industrial and near‐future CO2 than between near‐ and remote‐future CO2 concentrations. Hence, maternal effects of increasing CO2 may contribute to current changes in plant productivity and species composition, and they need to be considered when predicting impacts of global change on plant communities.
Testing masting mechanisms of boreal forest species at different stand densities
Authors: Rossi Sergio , Morin Hubert , Laprise Danielle , Gionest François
Published: November 2011

Mast seeding is considered a reproductive trait resulting from several potential evolutionary forces. Although the mechanisms driving reproduction have been thoroughly investigated and discussed, their relative importance and possible coexistence remain an open question. Seed rain abundance and viability of balsam fir Abies balsamea, white spruce Picea glauca, and white birch Betula papyrifera were monitored during 1994–2007 along a chronosequence of developmental stages at different densities represented by four stands in the boreal forest of Quebec, Canada. The aim of the study was to verify whether seeding temporal dynamics and abundance were affected by stand density, and to test the causal relationships between the hypotheses of pollination efficiency and predator satiation. Seed rain abundance varied substantially among years and species, with the highest values being observed in 1994 and 1996, and attaining up to 28.2 × 103 seeds m−2 year−1. However, the annual dynamics of seed production was similar in the three sites with the higher densities. The greater proportions of germinating and dead seeds were observed in white birch, while balsam fir showed an average of 11.2% of damaged seeds, which were infected by larvae. The conifer species had the higher proportions of empty seeds. The causal models tested on balsam fir demonstrated that seed rain abundance influenced the amount of both viable and larval‐infected seeds, although no causal relationship existed between these last two variables. The comparable and synchronous seed rain abundances observed among sites demonstrated that stand density can significantly affect the reproduction of trees, probably by limiting the access to resources, but not the annual dynamics of seeding. Pollination efficiency and predator satiation are important forces in the reproductive effort of trees and could be not mutually exclusive because both these mechanisms of natural selection synergistically coexist in driving the seeding dynamics of balsam fir.
Individually tracked geese follow peaks of temperature acceleration during spring migration
Authors: van Wijk Rien E. , Kölzsch Andrea , Kruckenberg Helmut , Ebbinge Barwolt S. , Müskens Gerhard J. D. M. , Nolet Bart A.
Published: November 2011

Many migratory herbivores seem to follow the flush of plant growth during migration in order to acquire the most nutrient‐rich plants. This has also been hypothesized for arctic‐breeding geese, but so far no test of this so‐called green wave hypothesis has been performed at the individual level. During four years, a total of 30 greater white‐fronted geese Anser albifrons albifrons was tracked using GPS transmitters, of which 13 yielded complete spring migration tracks. From those birds we defined stopover sites and related the date of arrival at each of these stopovers to temperature sum (growing degree days, GDD), snow cover, accumulated photoperiod and latitude. We found that geese arrived at spring stopovers close to the peak in GDD jerk; the ‘jerk’ is the third derivative, or the rate of change in acceleration, and GDD jerk maxima therefore represent the highest acceleration of daily temperature per site. Day of snow melt also correlated well with the observed arrival of the geese. Factors not closely related to onset of spring, i.e. accumulated photoperiod and latitude, yielded poorer fits. A comparison with published data revealed that the GDD jerk occurs 1–2 weeks earlier than the onset of spring derived from NDVI, and probably represents the very start of spring growth. Our data therefore suggest that white‐fronted geese track the front of the green wave in spring.
Phagocytic cell activity and periodontitis in Down syndrome
Authors: Khocht A , Russell B , Cannon JG , Turner B , Janal M
Published: November 2011

Oral Diseases (2012) 18, 346–352

Background:  This study investigated the phagocytic function of peripheral granulocytes and monocytes from adult individuals with Down syndrome (DS) and assessed the relation between phagocytic function and periodontal status.

Methods:  Fifty‐five DS individuals (18–56 years old), 74 mentally retarded individuals, and 88 medically healthy controls (HC) participated in the study. Gingival inflammation index, plaque index, probing depth, periodontal attachment level (AL), and bleeding on probing were taken for each subject. Whole blood was collected for granulocyte/monocyte phagocytosis tests. Phagocytic function was determined by flow cytometry in terms of percentage of cells actively involved in phagocytosis, and phagocytic intensity (magnitude of the bacterial staining per cell).

Results:  Phagocytic intensity of both granulocytes and monocytes was comparable in HC and DS subjects. While AL was directly related to phagocytic intensity of both granulocytes (r = 0.14, P = 0.03) and monocytes (r = 0.2, P = 0.003) in all subjects, this relationship was stronger in DS than in other subjects, even after controlling for known risk factors for periodontitis (P < 0.05). Monocyte phagocytic intensity was the only necessary predictor of AL (P = 0.003), indicating a similar relationship between AL and phagocytic activity in either cell type.

Conclusions:  While granulocyte and monocyte phagocytic intensities are similar in Down and non‐DS individuals, phagocytic intensity was associated with more AL in DS than non‐DS individuals.
Oxytocin in schizophrenia: a review of evidence for its therapeutic effects
Authors: MacDonald Kai , Feifel David
Published: November 2011

Background:The suggestion that the neurohormone oxytocin may have clinical application in the treatment of schizophrenia was first published in 1972. Since then, a considerable body of research on a variety of fronts – including several recent double-blind treatment trials – has buttressed these early reports, providing support for the assertion that the oxytocin system is a promising and novel therapeutic target for this devastating malady. Herein, we review the diverse, convergent lines of evidence supporting the therapeutic potential of oxytocin in psychotic illness.

Methods:We performed a systematic review of preclinical and clinical literature pertaining to oxytocin's role in schizophrenia.

Results:Multiple lines of evidence converge to support the antipsychotic potential of oxytocin. These include several animal models of schizophrenia, pharmacological studies examining the impact of antipsychotics on the oxytocin system, human trials in patients examining the aspects of the oxytocin system and several double-blind, placebo-controlled clinical treatment trials.

Conclusions:There exists considerable, convergent evidence that oxytocin has potential as a novel antipsychotic with a unique mechanism of action. Auspiciously, based on the few chronic trials to date, its safety profile and tolerability appear very good. That said, several critical clinical questions await investigation before widespread use is clinically warranted.
Decompression of large cystic lesions of the jaw: a case series
Authors: Sammut S. , Morrison A. , Lopes V. , Malden N.
Published: November 2011

Aim:  To present a series of clinical cases of large odontogenic cysts of the jaw treated with surgical decompression and insertion of a drainage stent.

Materials and methods:  Fourteen patients with jaw cysts of odontogenic origin were followed up from time of presentation until there was clinical and radiographic resolution of the cystic lesion. The cysts were all treated with surgical decompression and insertion of a stent.

Results:  In all cases, there was radiographic evidence of bony infill and complete resolution of the radiolucent area. In those cysts associated with an unerupted tooth, there was also evidence of spontaneous eruption. None of the patients suffered any serious post‐operative consequences.

Conclusions:  Decompression is a viable alternative to more aggressive techniques in the management of large cysts of the jaw. There is minimal post‐operative morbidity, and the technique may reduce the need for general anaesthesia.
An evaluation of a novel instrument for measuring macular pigment optical density: the MPS 9000
Authors: Loughman James , Scanlon Grainne , Nolan John M. , O’Dwyer Veronica , Beatty Stephen
Published: November 2011

Purpose:  Of the antioxidants found in the human retina, only the macular carotenoid quantities can be estimated noninvasively (albeit in a collective fashion), thus facilitating study of their role in that tissue. The aim of this study was to evaluate concordance between macular pigment optical density (MPOD) values recorded on a commercially available instrument, the MPS 9000, with those of an already validated heterochromatic flicker photometry instrument. Also, we assessed and compared test–retest variability for each instrument.

Methods:  Macular pigment optical density at 0.5 retinal eccentricity was measured using two different heterochromatic flicker photometers, the MPS 9000 and the Macular DensitometerTM, in 39 healthy subjects. Test–retest variability was evaluated separately for each instrument by taking three readings over a 1‐week period in 25 subjects.

Results:  There was a moderate positive correlation for MPOD at 0.5° of retinal eccentricity between the MPS 9000 and the Macular Densitometer described by the linear equation y = 0.763x + 0.172 (r = 0.68, p < 0.001, r2 = 0.46); however, a paired‐samples t‐test showed a significant difference in terms of mean values, with a bias of lower MPOD values being yielded by the MPS 9000 (t = −4.103, p < 0.001). Bland–Altman analysis indicated only moderate agreement between the two instruments, reflected in 95% limits of agreement of 0.1 ± 0.27. Inter‐sessional repeatability, expressed as a coefficient of repeatability, ranged from 0.18 to 0.21 [mean (±SD): 0.19 (0.02)] for the MPS 9000 and from 0.11 to 0.12 [mean (±SD): 0.12 (0.01)] for the Macular Densitometer.

Conclusion:  The results demonstrate that the MPS 9000 consistently yields MPOD readings, which are lower than that found with the Macular Densitometer, and exhibits substantial test–retest variability.
Effect of Discontinuation of Tamsulosin in Korean Men with Benign Prostatic Hyperplasia Taking Tamsulosin and Dutasteride: An Open‐Label, Prospective, Randomized Pilot Study
Authors: LEE Joo Yong , KANG Dong Hyuk , PARK Sung Yul , LEE Seung Wook , KIM Yong Tae , CHOI Hong Yong , MOON Hong Sang
Published: November 2011

Objective: This study was conducted to examine the effect of discontinuing tamsulosin in patients with benign prostatic hyperplasia who had been receiving combination therapy with tamsulosin and dutasteride.

Methods: The study sample consisted of 108 men with benign prostatic hyperplasia and lower urinary tract symptoms who visited our urology clinics between April 2008 and December 2010. All were assessed using the International Prostate Symptom Score (IPSS). The patients had IPSS of 8–19 and prostate volumes ≥25 mL by transrectal ultrasonography. They were put on tamsulosin and dutasteride, and the efficacy of this regimen was assessed every 12 weeks. After 48 weeks, patients were divided at random into a group continuing to take the same drug combination (group 1) and a group taking only dutasteride 0.5 mg (group 2).

Results: Sixty‐nine of the original 108 patients completed the study, 36 (52%) in group 1 and 33 (48%) in group 2. The mean age of all patients was 67.96 ± 7.88 years and mean prostatic volume was 40.45 ± 12.81 mL. Mean prostate‐specific antigen was 3.31 (0.4–9.9) ng/mL at the outset. The IPSS scores of the two groups at first visit, 48 and 72 weeks were, respectively, 14.69 versus 15.85 (P = 0.322), 12.08 versus 12.85 (P = 0.582) and 10.89 versus 11.06 (P = 0.897.) There was a statistically significant difference between the baseline and 72‐week IPSS scores in both groups (group 1: P < 0.001, group 2: P < 0.001).

Conclusion: In patients with moderate IPSS, discontinuing tamsulosin after 48 weeks of combined tamsulosin and dutasteride therapy has no significant effect on outcome.
Augmented reduction of islet β‐cell mass in Goto‐Kakizaki rats fed high‐fat diet and its suppression by pitavastatin treatment
Authors: Mizukami Hiroki , Inaba Wataru , Takahashi Kazunori , Inoue Keisuke , Sawanobori Kimio , Yagihashi Soroku
Published: November 2011

Aims/Introduction:  High fat diet (HFD) is known to be a risk for development of type 2 diabetes. It is unclear, however, how it affects the glucose tolerance or the islet structure in type 2 diabetes. The aim of this study is: (i) to examine the effects of HFD on the islet in GK rats, non‐obese type 2 diabetic model; and (ii) to explore if pitavastatin treatment influences the change.

Materials and Methods:  To see the effects of HFD on islet changes in type 2 diabetes, 4‐week old male GK and Wistar rats were fed HFD for 16 weeks and subjected to glucose tolerance tests and pathological studies of the islet. The effects of pitavastatin (3 mg/kg/day for 16 weeks, oral), one of the lipophilc statins, were also examined in both GK and Wistrar rats fed with or without HFD.

Results:  The HFD induced hyperlipidemia and aggravated glucose intolerance in both GK and Wistar rats. Pitavastatin treatment did not influence the glucose tolerance in HFD‐fed animals. HFD caused an increase in hepatic lipid contents in all the animals, which was partially suppressed by pitavastatin treatment. GK rats showed reduced β‐cell mass, and fibrosis and macrophage migration in the islets. HFD feeding in GK rats augmented these changes which were associated with enhanced expression of 8‐hydroxydeoxyguanosine and an increase in apoptotic cells. Pitavastatin treatment improved the HFD‐induced islet pathology, and pancreatic insulin contents paralleled the structural changes.

Conclusions:  HFD feeding worsened the islet pathology in GK rats which was suppressed by pitavastatin treatment. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00173.x, 2011)
Is acupressure an effective and low‐cost self‐administered treatment for dysmenorrhoea?
Authors: Melchart D , Eustachi A
Published: November 2011

Bazarganipour F, Lamyian M, Heshmat R, Abadi MA, Taghavi A.

A randomized clinical trial of the efficacy of applying a simple acupressure protocol to the Taichong point in relieving dysmenorrhea.

Int J Gynaecol Obstet 2010; 111: 105–9.
Efficacy and limitations of homeopathic and antibiotic treatments for bovine clinical mastitis
Authors: Terry R
Published: November 2011

Werner C, Sobiraj A, Sundrum A.

Efficacy of homeopathic and antibiotic treatment strategies in cases of mild and moderate bovine clinical mastitis.

J Dairy Res 2010; 77: 460–7.
Home Medicines Reviews: a quantitative study of the views of recipients and eligible non-recipients
Authors: Carter Stephen R , Chen Timothy F , White Lesle
Published: November 2011

Objective

There is a lack of knowledge regarding recipients' experiences with, perceptions of, and willingness to reuse the Home Medicines Review (HMR) programme in Australia. In addition, little is known about eligible non-recipients' awareness of and willingness to use the HMR service. The aim of the study was therefore to explore perceptions of, and willingness to use, HMRs.

Methods

A cross-sectional questionnaire was conducted with recipients and eligible non-recipients of HMRs. Eligible non-recipients were defined as those who had not had an HMR and were at risk of medication misadventure. The questionnaire was distributed by 264 practising pharmacists throughout Australia.

Results

A total of 595 out of 1893 (31%) HMR recipients and 293 out of 1829 (16%) eligible non-recipients completed the questionnaires. Overall, 91% of recipients were satisfied with the service. Compared with eligible non-recipients, recipients were more willing to have an HMR if their general practitioner (GP) suggested it (91% versus 71%, P < 0.001) and more willing to ask for an HMR if they were having concerns about their medicines (82% versus 63%, P < 0.001). Among eligible non-recipients, 23% were aware of HMRs. Predominantly pharmacists (68%) and GPs (36%) provided awareness of HMRs, which was associated with increased willingness to have an HMR if their GP suggested it (83% versus 67%, P < 0.014).

Conclusions

An overwhelming majority of patients were satisfied with the HMR programme. Experience with HMR, and to a lesser extent, prior awareness, increased willingness to use HMR. Therefore, pharmacists and GPs who introduce HMR to eligible non-recipients may increase their willingness to use this service.
Brain glycogen supercompensation following exhaustive exercise
Authors: Matsui Takashi , Ishikawa Taro , Ito Hitoshi , Okamoto Masahiro , Inoue Koshiro , Lee Min‐chul , Fujikawa Takahiko , Ichitani Yukio , Kawanaka Kentaro , Soya Hideaki
Published: November 2011

Non‐technical summary Exercise training elicits an increase in the basal level of muscular glycogen. This happens when glycogen recovers to above its basal level (supercompensation) after it decreases with acute exercise. Although untested, it is hypothesized that, similar to that of skeletal muscle, brain glycogen supercompensation occurs after acute exhaustive exercise. We provide evidence that exhaustive exercise induces glycogen supercompensation not only in skeletal muscles, but also in the brain. Furthermore, we observed exercise training‐induced increases in basal glycogen levels in the cortex and hippocampus, which are involved in motor control and cognitive function. This suggests that, like skeletal muscles, the brain adapts metabolically, probably to meet the increased energy demands of exercise training.
Very-Short-Time, Very-High-Temperature Creep Rupture of Type 347 Stainless Steel and Correlation of Data
Authors: Lundin C. D. , Aronson A. H. , Jackman L. A. , Clough W. R.
Published: November 2011

Available equipment initially developed for welding research studies was used to investigate the creep-rupture behavior of AISI type 347 stainless steel in a very-high-temperature range from 62 to 86 percent of the solidus. Stress applications from 900 to 28,000 psi gave rupture times from a fraction of a second to several hundred seconds with thousandfold variations of minimum creep rate. Results could be presented by conventional means. Data scatter on a Monkman-Grant plot was typical. Correlation and extrapolation procedures developed by Larson-Miller, Manson-Haferd, Dorn, Korchynsky, and Conrad for conventional long-time results were found to be applicable, with preference being given to the Manson-Haferd procedures.
Thermal Entry for Low Reynolds Number Turbulent Flow
Authors: Reynolds H. C. , Swearingen T. B. , McEligot D. M.
Published: November 2011

The thermal entrance problem for low Reynolds number, turbulent flow of gases in circular tubes is solved analytically by the method of Sparrow, Hallman, and Siegel. Fluid properties are considered constant. The solution is based on a Reynolds-number-dependent velocity profile developed, in a companion paper, by modifying Reichardt’s wall and middle law eddy diffusivity expressions. Tabular values of the eigenvalues and normalized Nusselt numbers are presented for a range of Reynolds numbers from 3,000 to 50,000. The axial variation of Nusselt number is found to be correlated by NuNu∞=1+0.8(1+70,000Re−3/2)xD−1 to within ±5 percent for x/D ≥ 2. The fully developed value agrees with the Dittus-Boelter correlation. For the eigenvalues, λn2, and the associated constants, An, correlations of the form λn2=a1,nRe−b1,n+c1,nRe−d1,nAn=a2,nRe−b2,n+c2,nRe−d2,n are obtained. Heat transfer data are presented, primarily for helium, for the conditions of the analysis. In the low Reynolds number turbulent regime, these data clearly support the present analytical solution.
A New Approach to the Solution of Linear Optimal Control Problems
Authors: Rugh W. J. , Murphy G. J.
Published: November 2011

A simplified approach to the solution of linear optimal control problems with quadratic performance indexes is described in this paper. The phase-variable canonical form is used to develop a new type of optimal system equivalence. This concept leads to a substantial simplification of the matrix Riccati equation. The simplified matrix Riccati equation is of the same form for any problem of a given order, say, n, and contains only n nonzero forcing functions. That is, it always corresponds to a set of constant-coefficient scalar differential equations; in various nth-order problems the n nonzero forcing functions and the terminal conditions simply assume different forms. In a very strong sense, this simplified matrix Riccati equation is the simplest possible Riccati equation arising from optimization problems. The method is developed for general time-varying systems with finite terminal time. It is developed also for the important special case of time-invariant systems with infinite terminal time.
Invariant Imbedding and Sequential Interpolating Filters for Nonlinear Processes
Authors: Kagiwada H. H. , Kalaba R. E. , Schumitzky A. , Sridhar R.
Published: November 2011

Suppose imprecise observations are made on imprecisely defined nonlinear processes, and one wishes to estimate the state of the process at certain fixed instants of time lying within the interval of observation. Furthermore, assume that it is required to update these estimates as additional observations become available. This is precisely the problem of sequential interpolation. The equations of the sequential interpolating filter, when a least-squares estimation criterion is used, are obtained in this paper. The interpolation problem is first shown to be equivalent to a two-point boundary-value problem. The two-point boundary-value problem is converted to an initial-value problem using invariant imbedding. The initial-value problem leads directly to a sequential filter.
The Performance of Pressure-Exchanger Dividers and Equalizers
Authors: Kentfield J. A. C.
Published: November 2011

Tests are reported which were carried out to establish the performance of pressure-exchanger dividers and equalizers using air as the working fluid. The effects of varying rotor speed, port geometry, and port pressure ratios were explored. It was concluded that, at low pressure ratios, pressure-exchanger dividers and equalizers are comparable in performance with their turbomachine counterparts.
One-Way Air Chambers for Pumping Plants
Authors: Kephart J. T.
Published: November 2011

The one-way air chamber for suppressing water-column separation is described. Operation of the one-way air chamber during a power failure transient is explained. A typical problem solution is shown. The one-way air chamber is compared with the one-way surge tank and the normal air chamber.
Cavitation Tests on Hydrofoils Designed for Accelerating Flow Cascade; Report 4—Three Profiles Designed for High Head Kaplan Turbine
Authors: Numachi F.
Published: November 2011

In pursuit of the studies previously reported [1–3], three profiles suited for application in the main blade elements of high head Kaplan turbines—two intended for sections near boss and one for sections around midway or two thirds along the blade arm—have been produced, and an account is given of the blade characteristics and performance in cavitation tunnel tests.
Velocity Distribution and Its Effect on the Accuracy of the Gibson Method of Water Measurement
Authors: Johnson G. Dugan
Published: November 2011

The author demonstrates that significant basic errors are introduced into the Gibson method of measuring water flow rates, even in uniform straight pipes, by failure to take account of velocity distribution in calculating results. Dr. Thoma’s 1926 analysis of the method is quoted extensively, including his conclusion that long straight lengths of pipe upstream and downstream from straight differential-diagram test sections would eliminate the effects of accessory motions and his recommendations for establishing an experimental installation to determine the effects of various disturbed flow conditions. The need for these correction factors or “meter coefficients” in order to avoid consistent errors of approximately 2 percent is emphasized.
Factors Influencing the Plane-Strain Crack Toughness Values of a Structural Steel
Authors: Shoemaker A. K.
Published: November 2011

An investigation was conducted to determine the effects of the variables; temperature, strain rate, and precracking fatigue-stress level, on plane-strain crack toughness values of a rate and temperature-sensitive steel. The crack toughness behavior of a 3/4-in-thick structural steel plate, which had a static room-temperature yield stress of 45,000 psi, was examined over the temperature range from −280 to 0 deg F for strain rates of 8 × 10−5/sec, 3 × 103/sec, and 1.5/sec. Crack toughness data, which were obtained from notched bend and single-edge-notched specimens, are presented for precracking conditions obtained at a maximum nominal fatigue stress of 25 percent and 50 percent of the room-temperature yield stress. The plane-strain crack toughness, KIc-values showed only a small sensitivity to changes in temperature and no effect due to changes in strain rate. The beginning of the transition from plane-strain to plane-stress conditions occurred at successive increases in temperature for increasing strain rate. The requirement of B > 2.5 × (KIc/σys)2 for plane-strain behavior of high-strength steels was also valid for this material when the yield stress was evaluated at the test temperature and strain rate. Increasing the fatigue-cracking stress level from 25 to 50 percent of the room-temperature nominal yield stress increased the apparent KIc-values. The data showed that a necessary condition for obtaining valid KIc-values is that the plastic-zone size which develops during fatigue cracking at room temperature must be less than that which occurs at the low temperatures and elevated strain rates of the KIc tests.
Corrosion Fatigue in Surgical Implants
Authors: Colangelo V. J.
Published: November 2011

Orthopedic appliances of type 316 SMO were examined after removal from human subjects. Fractographic evidence, macroscopic and microscopic, is presented together with the overall incidence of fracture and fatigue for the specimens examined. Bend fatigue tests were conducted in air and in isotonic saline solution (0.9 percent NaCl) and the crack-growth rates determined. Data followed the empirical relationship proposed by Paris [5]: da/dN = C(ΔK)m with m rising from 3.23 in air to 4.16 for isotonic saline. A distinct change in the appearance of the fracture surface was noted on the specimens broken in the saline environment. The specimens broken in air were bright, while the specimens fatigued in 0.9 percent NaCl were darkened with corrosion products.
Electrodynamic Oscillating Compressors: Part 2—Evaluation of Specific Designs for Gas Loads
Authors: Cadman R. V. , Cohen R.
Published: November 2011

In Part 1, electrodynamic drivers are designed for a single, linearized load. In this part, a digital computer simulation program is described. This program more accurately models the nonlinearities of the actual gas load, and can be used to check the performance of candidate designs over the expected range of loading conditions. Two selected designs, a laboratory research compressor and a commercial electrodynamic compressor, were discussed in Part 1. Simulation results for the former are discussed and compared to experimentally measured data. For the latter, a comparable design, also presented in Part 1, is simulated and the results are discussed.
Small-Amplitude Frequency Behavior of Fluid Lines With Turbulent Flow
Authors: Brown F. T. , Margolis D. L. , Shah R. P.
Published: November 2011

The results of semiempirical analytical and experimental studies of the acoustic frequency response of circular tubes with a mean turbulent flow are given. For the frequency range tested, it is seen that the hypothesis of a time-invariant eddy viscosity profile across the tube predicts the behavior well. For lower frequencies a simple lag in the turbulence profile from its equilibrium values is hypothesized which should be of moderate importance in acoustic behavior and of great importance in large-amplitude behavior. The lag is estimated using the steady-flow results of Goldberg.
Strictly Sinusoidal Flow Around a Stationary Cylinder
Authors: Ward E. G. , Dalton C.
Published: November 2011

The forces exerted upon a cylinder subjected to a purely sinusoidal flow (no mean flow) are analyzed. The analysis considers flows in which symmetrically located vortex pairs are formed and shed from the cylinder. The flow field is described using potential flow theory and the lumped-vortex model is incorporated to handle the growth of the vortices. The instantaneous locations and strengths of the vortices are calculated. This information is used with the extended Blasius theorem in order to determine the forces acting upon the cylinder. The vortex growth behavior is compared to that obtained by experiments in which similar flows are observed.
Effect of Axial Compression on Low-Cycle Fatigue of Metals in Torsion
Authors: Mazelsky B. , Lin T. H. , Lin S. R. , Yu C. K.
Published: November 2011

Thin-walled tubular specimens of aluminum alloy 2024-T351, stainless steel 347, and beryllium copper 25 under static axial compressive stresses were tested in low-cycle fatigue in torsion. The data obtained indicates that compressive stress increases the low-cycle fatigue life of all these materials. This effect is similar to the effect of hydrostatic pressure which improves the fatigue behavior of metals under torsion as reported by previous investigators. Cyclic torsion tests with no axial stress were also conducted on these metals. The results of these cyclic torsion tests without axial stress can be well approximated by the empirical low-cycle fatigue relation proposed by Coffin [1]2 and Manson [2].
An Experimental Investigation of Fracture Criteria for Combined Extension and Bending
Authors: Wynn R. H. , Smith C. W.
Published: November 2011

Experiments were performed on cracked plates loaded in combined extension and approximately cylindrical bending. A fracture criterion was developed from the Sih-Hartranft bending theory, which, when modified to account for precatastrophic crack extension, agreed well with the experiments in regions where the crack remained open at fracture and appeared to provide a lower bound in the region where crack closure occurred.
Bubble Trajectories and Equilibrium Levels in Vibrated Liquid Columns
Authors: Foster J. M. , Botts J. A. , Barbin A. R. , Vachon R. I.
Published: November 2011

An analysis of bubble behavior in a vertically vibrated liquid column and experimental results of equilibrium level determinations are presented. The analysis avoids the usual approximation of small bubble pulsation and predicts a nonharmonic volume pulsation; it can be used to predict bubble trajectories and equilibrium levels. The vibrational amplitude affects the bubble motion indirectly through its effect on the thermodynamic behavior of the bubble. The experimental results compare favorably with the analysis.
A Study of the Notch Effect and of Specimen Design and Loading on the Fatigue Properties of Cast Steel
Authors: Wallace J. F. , Vishnevsky C. , Briggs C. W.
Published: November 2011

Scope of the research report: The purpose of the research included in this report is to extend the knowledge on the fatigue properties of cast steel by presenting a study of the effect of notches on fatigue properties and the effect of specimen design and the method of loading on the fatigue properties of cast steel. Summary of the research report conclusions: (a) Notch Effect—A severe notch (0.015-in. radius) in fatigue testing of cast steel results in a 36 percent reduction in endurance limit based on unnotched specimens. An extremely severe notch (0.001 in. radius) results in a 42 to 53 percent reduction in the endurance limit. The fatigue strength reduction factor Kf for extreme notched specimens is appreciably higher for cast steel in the quenched and tempered condition. (b) Specimen Design and Loading—Cast steel exhibits better endurance properties in reversed torsion than reversed bending. Bending fatigue tests of cast steel tested at 1800 rpm result in lower endurance properties than rotating beam tests at 10,000 rpm. The difference is greater at the higher tensile strength level.
Speed Regulation Study for Bay D’Espoir Hydroelectric Generating Station
Authors: Newey R. A.
Published: November 2011

An island-wide power network has recently been built in Newfoundland, linking together the various local power systems for the first time. Power for this network will be provided from Bay d’Espoir powerhouse. Since most of the power stations already in operation are small and have slow governor times, it was important that the Bay d’Espoir units be able to respond quickly to major changes of load. A detailed study was therefore carried out using a computer to optimize the design parameters, the results obtained providing a detailed picture of the frequency changes resulting from various load changes on the system, and the corresponding water hammer and surge tank level fluctuations. A second study, now under way for the next stage of the project, shows the effect of increased load changes on the larger system.
The Split, Layered, Cup-and-Cone Tensile Fracture
Authors: Hrubec R. J. , Jackman L. A. , Clough W. R.
Published: November 2011

Quenched and tempered plate steel is capable of modified cup-and-cone fractures involving one or more longitudinal cracks “parallel” to the flat plate surfaces. The occurrence was verified by tensile testing of three steels at a variety of temperatures. Electron fractography revealed that quasi-cleavage, shear lips, tearing, and normal rupture were active, being identified by modified river patterns and by elongated and equiaxed dimples resulting from the coalescence of microvoids. The brittle longitudinal cracks are formed shortly before final rupture. Application of the Bridgman plasticity solution for necked tensile specimens shows that the split, layered, fracture occurs under unique stress conditions.
The Stability of a Simple Surge Tank
Authors: Duggins R. K.
Published: November 2011

An equation is derived to describe small oscillations in a simple surge tank for a wider range of operating conditions than hitherto considered. It is presented in a new non-dimensional form which facilitates an immediate prediction of surge phenomena when small disturbances are imposed on any given set of steady-state conditions. A characteristic of general form is assumed for conduit friction, and the effect is considered of deviation from the condition of constant hydraulic power delivered to the turbine. Some experiments have been carried out with a laboratory model simulating a variety of steady-state operating conditions, and surge measurements are presented for comparison with the calculated behavior.
Computerized Method of Characteristics Calculations for Unsteady Pneumatic Line Flows
Authors: Manning J. R.
Published: November 2011

Prior to development of high-speed digital computers, the method of characteristics has not been readily available for pneumatic system design. The traditional organization of computations on a free-running grid is not ideal for machine work. In a 1953 paper, Hartree developed the mathematical foundation for method of characteristics computations on a rectangular grid of predetermined dimensions. The present paper develops in detail a rectangular grid scheme for pneumatic line analysis. An approximate method for tapered lines is presented. Line termination computations are discussed for the general case, together with examples developed in connection with recent resonance tube research conducted by the author. Some computed results for constant area and tapered resonance tube simulations are presented.
On the Stresses Near an Oblique Elliptical Aperture in a Large Plate
Authors: Francis P. H. , Gormley J. F.
Published: November 2011

An experiment was performed to determine the nature of the elastic stress system in the vicinity of an elliptical aperture in a plate subjected to uniform in-plane uniaxial tension, when the aperture is oblique to the plate midsurface. It was found that the maximum circumferential stress is somewhat higher than predicted by the Inglis solution for the “corresponding” plane problem. The possible relevance of these findings to elastic fracture mechanics is discussed.
Ductile Creep Rupture of Shells With Strain Hardening and Time-Dependent Loading
Authors: Reese C. D. , Bert C. W.
Published: November 2011

This paper presents an analysis of the tensile instability phenomenon in a thin-walled membrane shell of revolution undergoing creep while subjected to a time-dependent internal pressure. Time-independent plastic deformation due to biaxial stress, including strain hardening and biaxial-stress creep, are included. The theory is applied to an example of a typical closed-end cylindrical pressure vessel to emphasize the importance of considering both plastic and creep deformations due to biaxial stress in calculations of ductile creep rupture.
Water-Column Separation at Two Pumping Plants
Authors: Brown R. J.
Published: November 2011

Results of field measurement of transients in two pump discharge lines show that the pressures were greater than had been predicted during design, and a theory and method of analysis are developed which explains the time-history of the transients measured. The field measurements were undertaken because of the complexity of the phenomena and because very little measured data were available. Results are presented graphically along with analytical solutions. Conclusions drawn were: (a) The inherent difficulty of prediction of water-column separation effects is further complicated by the uncertainty about complete pump operating characteristics and actual moment of inertia of pumps and motors; (b) the effects of air and gases entrained in solution in the water must be considered in the analytical solution; and (c) entrained air can have a detrimental effect on the water-hammer transient, i.e., larger pressure surges in the discharge line and higher reverse speeds of the pumps can be caused by its presence.
A Suction Scheme Applied to Flow Through Sudden Enlargement
Authors: Heskestad G.
Published: November 2011

This paper describes an experimental study of the incompressible flow through a step expansion in a circular pipe as affected by suction through an annular gap lining the convex corner of the step. A uniform inlet flow with thin boundary layer is considered. Application of suction at a rate greater than some critical value caused the flow to expand rapidly into the larger diameter (basic effect previously termed an “edge suction effect”), the degree of expansion greatly dependent on gap orientation and size. Critical suction rates have been determined and other data collected to evaluate the configuration as a (short) diffuser.
The Formation of a Shock Wave in a Blade Passage of a Partial Admission Turbine
Authors: Woods W. A. , Chu F. Kuo-Hua , Mann R. W.
Published: November 2011

The problem of unsteady flow in the blade passage of a partial admission impulse turbine with supersonic nozzle flow is introduced. Previous work carried out at M.I.T. revealed the presence of a shock wave at the entrance to the blade passages and this report sets out to predict the formation of such a shock wave using a one-dimensional theory. The one-dimensional theory is discussed in some detail and a novel method for dealing with the inflow boundary conditions is developed. Details of a characteristic calculation are given, and this is matched with a shock wave analysis to predict the formation of the shock wave. The implications of the theoretical work are discussed and experimental results obtained from a hydraulic analogy are presented which confirm the analysis.
Experiments on Laminar Flow Development in Rectangular Ducts
Authors: Sparrow E. M. , Hixon C. W. , Shavit G.
Published: November 2011

The development of the laminar velocity and pressure fields in the hydrodynamic entrance region of rectangular ducts has been explored experimentally. Duct cross sections having aspect ratios of 5:1 and 2:1 were employed in the investigation; air was the working fluid. It was found that the development of the pressure field is much more rapid than that of the velocity field. The entrance length, relative to pressure development, is representable as (z/De)/Re = 0.02 for both ducts. The incremental pressure drop due to the development of the flow was deduced from the experimental data as being approximately equal to one velocity head. The axial development of the velocity field is illustrated by a sequence of velocity profiles measured along the symmetry lines of the cross section. The flow development in the 5:1 duct is found to be somewhat more rapid than in the 2:1 duct. Comparisons of the experimental results are made with available predictions of analysis, all of which are based on approximate models of the flow field. In general, the analyses over predict the incremental pressure drop due to flow development. The development of the velocity field appears to be reasonably well described by analysis.
Detailed Damage Characteristics in a Cavitating Venturi
Authors: Robinson M. J. , Hammitt F. G.
Published: November 2011

Detailed observations of cavitation pitting and the accompanying flow regime in cavitating venturis using water and mercury have been made. From these it is tentatively concluded that microjet impingement is the most important damaging mechanism for this type of flow, which is generally typical of much fluid flow machinery. Effects of grain size on damage rate are measured as is the surface-hardening due to cavitation attack. Correlations of limited generality are presented between accumulated damage and material mechanical properties, leading to the tentative conclusion that no such general correlation is possible.
Effect of Shear Flows on the Outlet Angle in Axial Compressor Cascades—Methods of Prediction and Correlation With Experiments
Authors: Lakshminarayana B. , Horlock J. H.
Published: November 2011

A theory is presented for accurate prediction of the spanwise variation of outlet angle in axial compressor cascades, taking into account the effects of secondary flow, Bernoulli surface rotation, and spanwise flow displacement due to tangential vorticity and viscosity. The values of outlet angle predicted by this method are compared with experimental results obtained in various cascades (Louis [13], Soderberg [16], and Lakshminarayana [7]) in which the approach velocity was varied artificially in the spanwise direction by creation of a wake. The strength of secondary vorticity is reduced substantially by viscous effects and to a small extent by Bernoulli surface rotation. Conventional secondary flow theories which ignore these effects tend to overestimate the spanwise variation in outlet angle. An accurate estimate of the kinetic energy of the secondary flow is made.
Fatigue Crack Propagation in Low-Alloy Heat-Treated Steels
Authors: Brothers A. J. , Yukawa S.
Published: November 2011

The rates of fatigue crack propagation in several heat-treated steels were determined for several alloy steels heat-treated to yield strengths in the range 70,000 to 125,000 psi. For one steel crack growth rates were determined for both a thick notch bend specimen and for thin notched plate specimens. It is observed that the concepts of Griffith-Irwin fracture mechanics successfully correlate crack growth rates in the various geometry and thicknesses employed. However, the specific relationship is dependent on yield strength level. Microscopic examination suggests in some instances that inclusion segregates act effectively to locally accelerate crack growth rates.