bluuebunny/crossref_metadata_2025 huggingface dataset:
A Case of Sepsis-induced MODS Section in Disseminated Filariasis: Cause or Co-incidence
Authors: Bargali Arun , Mishra Rashmi , Mathews Sharon T , Kumar Naresh , Rohatgi Ishan
Published: February 2024

Filariasis, an affliction caused by thread-like filarial worms, poses a formidable health challenge in India, with diverse regional endemicities. It manifests in two distinct forms: lymphatic and extralymphatic. The former induces agonising limb swelling, while the latter, often overlooked due to its atypical presentation, can affect various organs. Here we, present a noteworthy case involving a 25-year-old woman who succumbed to septic shock, displaying Multiple Organ Dysfunction Syndrome (MODS). The patient exhibited bicytopaenia, leukocytosis, and progressively deteriorating liver and kidney functions, culminating in Acute Respiratory Distress Syndrome (ARDS). Postmortem examinations, conducted with proper consent, revealed sheathed microfilaria in liver and bone marrow tissues. This rare multisystem involvement in filariasis, leading to a fulminant course, raises questions about potential immunosuppression triggered by disseminated filarial dissemination. The hypothesis centres on the notion that the systemic spread of filaria might underlie the severe and rapid deterioration observed in this unique case, shedding light on the intricate dynamics of this parasitic disease and its implications for immune function.
Role of Audio Visual Aids to Impart Garden-Based Nutrition Education for Preschoolers
Authors: Abhina B.  , Beela G. K.
Published: February 2024

Introduction: One of the most critical period in human life is the preschool years. In order to develop healthy food habits nutrition education need to be imparted at this age. There is a novel strategy to deliver nutrition education to children namely Garden-Based Nutrition Education (GBNE). Utilization of nutrition education tools can be an effective way for the delivery of GBNE.

Aim: To develop PowerPoint presentation on the importance of fruits and vegetables converts to video form and a child friendly gardening video for preschool children and assess the feasibility and acceptability.

Materials and Methods: Audio visual aids like power point presentation and videos were developed. Power point presentation on importance of fruits and vegetables was developed in such a way that it can reach the respondents and convey the intended message for preschool children with a total of 13 slides.

A documentary child friendly gardening video was constructed having a duration of nearly seven minutes with the title “Garden Based Nutrition Education” with the intention to inculcate gardening skills among children from their early childhood years. Both the tools were developed using standardized procedures and was subjected to pre study. In order to assess the feasibility and acceptability of the developed GBNE tools it was subjected to preschool teachers/anganwadi workers and parents of preschool children. The sample consisted of 75 parents and 75 preschool teachers which was randomly selected from Kollam and Thiruvananthapuram districts of Kerala.

Results: The study reveals that, both parents and teachers finds child friendly gardening video as the most feasible and acceptable tool to impart garden-based nutrition education.

Discussion: Preschool children loves gardening ad watering. Child friendly gardening video is most involving and interesting in nature when compared to power point video.

Conclusion: Therefore it can be concluded that power point video on importance of fruits and vegetables and child friendly gardening video can be used as effective GBNE tool to teach the significance of fruits and vegetables through gardening activities.
Modelling the Relationships of Psychosocial Hazard and Workplace Safety Outcomes among Construction Workers in Rivers State, Nigeria
Authors: Ekeke Kelechi D. , Nwaogazie Ify L. , Nnadede K. S.
Published: February 2024

This research was carried out to investigate the relationship between psychosocial hazards and safety outcomes among workers engaged in a range of industrial construction occupations in Rivers State. Questionnaires were adapted from various studies and were distributed. Two-hundred and ninty-five (295) respondents had a complete and usable questionnaire. A conceptual model was posited for this study, the model comprises of equipment and environment, work schedule, role organisation, social aspect, organisational culture, and work life balance as the workplace psychosocial hazards and near miss, accident, absenteeism, and job performance as the safety outcomes on the study. Structural equation modelling was then used to test the conceptual model and test the hypotheses using SPSS AMOS software. The result from the study shows that all six workplace psychosocial hazards used in the study had direct significant relationship with the accident safety outcome at p-value (< 0.05). The result also shows that environment and equipment, role in the organization, social aspect and work-life balance showed significant relationships with near miss safety outcome at p-value .05. The study also inferred that equipment and environment, work schedule, role organisation, social aspect, and organisational culture are factors in the workplace that may be associated with absenteeism. The impact of psychosocial hazards experienced by construction workers is an area of growing research as this study has shown, which is yielding results that suggest overall work safety on the construction site should consider psychosocial aspects of work.
Study on Rachis Characters of Different Cultivars of Banana
Authors: Karmakar Mihir , Mondal Tanmoy , Mohanta Rajdeep , Mandi Gouri , Mahato Subrata , Bauri Fatik Kumar
Published: February 2024

Banana is one of the most important staple food around tropics. Bananas can be eaten as green when it is starchy. These crops are the most important components for food security around world by providing income to the farming community through local trade. This experiment was conducted to study the rachis behaviour and male bud characteristics of ABB genomic group and AAB genomic group banana cultivars. Here 5 cultivars under ABB genomic group (Behula, Bara Beglo, Bluggoe, Green Bombay, Pantharaj) and 5 cultivars of AAB genomic group (Dudhsagar, Martaman, Manohar, Desi Malbhog, Kalibhog) were observed. All of these 10 cultivars showed different characteristics in case of male bud, like male bud shape, male bud size, colour of the bract (external face), male bract lifting, wax on the bract, male flower behaviour, compound tepal basic colour, anther colour, stigma colour, ovary shape and dominant colour of male flower, all these were explained in details in this study.
Development of Pink Pigmented Facultative Methylotrophs’ (PPFMs) Consortium Formulation and Its Efficacy on Chilli (Capsicum annuum)
Authors: Solanki J. P.  , Vyas R. V.  , Jhala Y. K  , Patel H. K.
Published: February 2024

This research aims to investigate the potential effect of Pink Pigmented Facultative Methylotrophs (PPFMs) as foliar application to enhance growth parameters of chiili crop. The laboratory and pot studies were conducted at Department of Agricultural Microbiology, Anand Agricultural University, Anand. The PPFMs were isolated from the phyllosphere of solanaceous crop (Chilli, Brinjal, Potato, Tomato and Tobacco) and five out of thirty isolates were selected based on their methanol consuming and plant growth promoting traits. Consortium of isolates (Methylobacterium populi AAU PPFM C-7, M. radiotolerans AAU PPFM C-17, M. populi AAU PPFM C-19, M. populi AAU PPFM T-2 and M. radiotolerans B-2) were prepared after studying their compatibility. Pot study was laid out in net house using completely randomized design with four replications on Chilli crop. The results of the study showed significant effect of PPFMs consortium on growth parameters of chilli (viz. shoot length, root length, shoot weight, root weight, number of branches per plant) that could be result of the plant growth promoting traits of PPFMs.
On Projection Properties of Monotone Integrable Functions
Authors: Olwamba Levi Otanga
Published: February 2024

This research formulates an \((i-1, i)\) - dimensional structure of \(\mu_{|f|^p}^{(i-1, i)}\)-vector measure integrable functions for \(i=1,2, \ldots n\). Fixed point projection properties of a vector measure are appplied to determine the measurability of sets in the domain of integrable functions. Measurable sets of the form \(\Pi_i A_{i-1}^{(i, i+1)}\) are partitioned into disjoint sets \(\Pi_i A_{i-1}^i\) of finite measure.The obtained results demonstrate utility of concepts of vector measure duality, continuity from below of a measure and monotonicity of a vector measure in integrating functions.
Statistical Investigations on Relationship of Intraocular Pressure with Environmental Factors
Authors: Pedro Lata , Ana Lazaro , María Lopez José , Beatriz Palma , Cristina Sanchez , Carmelo Baños , Irene Sanchez
Published: February 2024

Clinical relevance: Intraocular pressure (IOP) has a significant role in glaucoma pathophysiology. There are factors that influence in the IOP value, such as central corneal thickness or the biomechanical properties of the cornea. However, other less studied factors may influence the IOP, such as environmental pollution.

Background: The increase in air pollution is related to acute respiratory pathologies. Regarding the eyes, is related to conjunctivitis or dry eye disease. The purpose was to analyse the correlation of environmental factors (atmospheric pressure, temperature, O3, NO2, PM10 and PM2.5 concentrations) with intraocular pressure in young healthy patients.

Methods: A cross-sectional study was carried out on patients treated at General Optica centres in Spain and Portugal in collaboration with the University of Valladolid. This study included healthy patients (between 18 and 40 years old). IOP measurements were taken with different air tonometers (CT-80, CT-800, NCT-200, NT-510 and NT-530) for one week and correlated with environmental factors (atmospheric pressure, temperature, O3, NO2, PM10 and PM2.5 concentrations). Correlation (Spearman’s Rho) analyses were performed between IOP and the different environmental parameters. Moreover, groupings were performed as a function of the values for healthy exposure levels recommended by the WHO. Different comparisons were performed using the Mann‒Whitney U test.

Results: Statistically significant correlations were found (p < .04) between IOP and temperature (r = 0.37), atmospheric pressure (r = 0.20), NO2 (r = 0.14), PM10 (r = 0.21), O3 (r = 0.16) and PM2.5 concentrations (r = 0.16). Regarding the IOP values of people who were exposed to unhealthy concentrations (AQI > 20) versus those who were not, higher IOP values were only found in people exposed to PM2.5.

Conclusion: Slight correlations were found between higher temperature, atmospheric pressure and concentrations of pollutant gases and increased IOP. More clinical studies are needed to understand the role that these environmental factors play in the aqueous humour flow and the value of IOP to know if and to what extent these factors may be risk of glaucoma.
Relationship of single measures of cardiorespiratory fitness and obesity in young schoolchildren
Authors: Mota Jorge , Flores Luana , Flores Luís , Ribeiro José C. , Santos Maria P.
Published: April 2006

The purpose of this study was to examine differences of cardiorespiratory fitness (CRF) among weight groups, and the associations of CRF with obesity (body mass index) in a sample of young children. Anthropometric data (height, body mass, and two skinfolds) were collected for 255 healthy children aged 8–10 years (127 boys and 128 girls). Children were placed in three groups (nonobese, overweight, and obese), using body mass index (BMI) sex‐ and age‐specific cutoff points. Cardiorespiratory fitness was assessed with a 1‐mile run test. Participants were separated into two groups: fit and unfit, according to age‐ and sex‐specific scores defined by FITNESSGRAM. The prevalence of overweight (30.5% vs. 29.1%) and obesity (13.2% vs. 12.6%) was at the same magnitude for boys and girls. Overall, 109 children (42.7%) were overweight and obese. Sums of skinfolds, weight, and BMI were significantly lower (P < 0.05) in lean boys and girls compared to their overweight and obese counterparts. Regarding height, no significant differences were found in girls, while in boys, significant differences were only found between nonobese and obese. No differences were found in obesity groups according to CRF in boys, while significant differences were found for girls (P < 0.01). Logistic regression analysis showed that girls who were overweight (odds ratio = 0.05, P = 0.000) or obese (odds ratio = 0.09, P = 0.001) were likely to be unfit. No significant results were found in boys. Overweight and obese children presented higher sums of skinfolds and weight compared with their lean counterparts. Increased BMI was significantly associated with lower CRF in girls. Thus, our data clearly showed potential gender differences of body composition in CRF, which would be of great clinical significance. Therefore, even at young ages, at least for girls, the beneficial impact of low BMI values on CRF is shown with important clinical and public health implications. Am. J. Hum. Biol. 18:335–341, 2006. © 2006 Wiley‐Liss, Inc.
The Mine Safety and Health Administration's criterion threshold value policy increases miners' risk of pneumoconiosis
Authors: Weeks James L.
Published: April 2006

Background

The Mine Safety and Health Administration (MSHA) proposes to issue citations for non‐compliance with the exposure limit for respirable coal mine dust when measured exposure exceeds the exposure limit with a “high degree of confidence.” This criterion threshold value (CTV) is derived from the sampling and analytical error of the measurement method.

Conceptual Framework

This policy is based on a combination of statistical and legal reasoning: the one‐tailed 95% confidence limit of the sampling method, the apparent principle of due process and a standard of proof analogous to “beyond a reasonable doubt.”

Critique

This policy raises the effective exposure limit, it is contrary to the precautionary principle, it is not a fair sharing of the burden of uncertainty, and it employs an inappropriate standard of proof. Its own advisory committee and NIOSH have advised against this policy. For longwall mining sections, it results in a failure to issue citations for approximately 36% of the measured values that exceed the statutory exposure limit.

Discussion

Citations for non‐compliance with the respirable dust standard should be issued for any measure exposure that exceeds the exposure limit. Am. J. Ind. Med. © 2006 Wiley‐Liss, Inc.
Osteoporosis in a population from medieval Norway
Authors: Mays S. , Turner‐Walker G. , Syversen U.
Published: April 2006

Modern populations from Norway and England differ in their experience of osteoporosis, the former showing lower bone mineral density (BMD) and a higher fragility fracture rate. The aim of the present work was to investigate whether this was also the case during the Middle Ages. Age‐dependent loss of BMD in the proximal femur was assessed using dual X‐ray absorptiometry (DXA) in male and female adult skeletons from a cemetery in the medieval town of Trondheim, Norway. Fracture prevalence was also investigated. Results were compared with those previously reported for a skeletal series from Wharram Percy, a deserted medieval village in England. Results indicate that peak BMD and patterns of age‐related loss of BMD in the Norwegian and the English group were similar. Among females, the prevalence of osteoporotic fractures was greater in the Norwegian than in the English population. The BMD results suggest that differences in BMD between English and Norwegians are of recent origin, although given the fairly modest sample sizes, further work is needed to confirm this. Reasons for the greater prevalence of osteoporotic fractures in women in the Norwegian skeletal series are unclear, but the colder climate and greater frequency of hard surfaces may have meant that falls were more frequent, and when they occurred, were more likely to result in fractures than in the rural English group. Am J Phys Anthropol, 2006. © 2006 Wiley‐Liss, Inc.
Spondylolysis, spondylolisthesis, and lumbo‐sacral morphology in a medieval English skeletal population
Authors: Mays S.
Published: April 2006

The prevalence of spondylolysis and spondylolisthesis was studied in an adult skeletal series from a rural English medieval archaeological site. Attempts were made to evaluate the association of three aspects of lumbo‐sacral skeletal morphology (pelvic incidence (a measure of the anterior inclination of the sacral table), lumbar transverse process width, and the presence of lumbo‐sacral spina bifida occulta) with spondylolysis and spondylolisthesis. Results indicated a high prevalence of spondylolysis compared with a modern reference population, but few cases of spondylolisthesis were identified. Analysis of prevalence with respect to age suggests that in the study population, pars interarticularis defects generally formed late in the growth period or early in adult life. The study group showed a high mean pelvic incidence compared with modern Western Europeans, indicating a more steeply inclined sacral table, which may have elevated the risk of developing pars interarticularis defects. However, no statistically valid association could be demonstrated between the presence/absence of spondylolysis and pelvic incidence in the study material. There was no evidence for a link between lumbar transverse process index or lumbo‐sacral spina bifida occulta and spondylolysis/spondylolisthesis. It is concluded that the potential role of lumbo‐sacral morphology, as well as of activity regimes, should be considered when interpreting spondylolysis in paleopathological studies. If the frequency of spondylolysis is to some extent an indicator of past activity regimes, it may reflect lifestyle in younger individuals rather than in mature adults. Further work investigating the link between spondylolysis and lumbo‐sacral morphological variables in premodern populations would be of value. Am J Phys Anthropol, 2006. © 2006 Wiley‐Liss, Inc.
Magnetic Properties and Interstitial Atom Effects in the Ln(Fe,M)12 Compounds
Authors: Yang Jinbo , Yang Yingchang
Published: April 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
The Oxa‐Pictet—Spengler Cyclization: Synthesis of Isochromans and Related Pyran‐Type Heterocycles
Authors: Larghi Enrique L. , Kaufman Teodoro S.
Published: April 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Asymptotic stability of the relativistic Maxwellian
Authors: Hsiao Ling , Yu Hongjun
Published: April 2006

Global classical solutions near the relativistic Maxwellian are constructed for the relativistic Boltzmann equation in both a periodic box and the whole space. For both cases, we are able to get the non‐negativity of the global solution under less restriction than in (Publ. Res. Inst. Math. Sci. 1993; 29:301–347) on the scattering kernel. Copyright © 2006 John Wiley & Sons, Ltd.
Non‐linear stability for convection with quadratic temperature dependent viscosity
Authors: Vaidya Ashwin , Wulandana Rachmadian
Published: April 2006

In this paper, we study the non‐linear stability of convection for a Newtonian fluid heated from below, where the viscosity of the fluid depends upon temperature. We are able to show that for Rayleigh numbers below a certain critical value, Rac, the rest state of the fluid and the steady temperature distribution remains non‐linearly stable, using the calculations of Diaz and Straughan (Continuum Mech. Thermodyn. 2004; 16:347–352). The central contribution of this paper lies in a simpler proof of non‐linear stability, than the ones in the current literature, by use of a suitable maximum principle argument. Copyright © 2006 John Wiley & Sons, Ltd.
Tracking pedestrians using multiple single‐row laser range scanners and its reliability evaluation
Authors: Nakamura Katsuyuki , Zhao Hujing , Shibasaki Ryosuke , Sakamoto Kiyoshi , Ohga Tomowo , Suzukawa Naoki
Published: April 2006

In this paper the authors propose a method for pedestrian tracking using multiple laser range scanners and describe verification experiments in a railway station. The proposed method involves synchronizing multiple laser scanners using a network and tracking pedestrians based on range data for foot cross‐sections. The tracking algorithm consists of the following functions: detection of foot candidates using range data clustering; detection of pedestrian candidates using grouping of foot candidates; detection of movement vectors for pedestrian candidates; extended processing of existing tracings using an extended Kalman filter based on a walking model. The results of using the proposed method in a station concourse in Tokyo Station found that at a maximum 150 people could be tracked at the same time. The tracking precision exceeded 80% during commuter rush hour. Applications to high‐precision crowd observations in wide areas can be expected. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(7): 1–11, 2006; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/scj.20578
Larval distribution and growth of the rockfish, Sebastes capensis (Sebastidae, Pisces), in the fjords of southern Chile
Authors: Landaeta Mauricio F. , Castro Leonardo R.
Published: April 2006

The distribution and the growth of larval rockfish Sebastes capensis were studied during two oceanographic cruises carried out in a sector of the Chilean fjords (43°30′S–46°S) during spring 2002 (November) and winter 2003 (August). Abundance (up to 600 per 10 m2) of pre- and post-flexion larvae was higher during the austral spring than in winter (20 per 10 m2). Larvae were smaller principally above the halocline in the first 50 m of the water column throughout the channels and fjords; in contrast, post-flexion larvae were more abundant seawards and were totally absent in the freshest waters. Analysis of the otoliths indicated that larvae between 3.3 and 12.2-mm standard length collected during November grew 0.15 mm d−1. Additionally, it showed that older larvae from the outer part of the channels and over the shelf laid down wider otolith increments than larvae found in the interior waters, coinciding with the area of greatest abundance of larger calanoid copepods. Ontogenetic differences in distributions suggest that different habitats are utilized during the early life stages of S. capensis, and that they seem to be shared with several other Sebastes species. However, the mechanisms for transport in different areas vary widely, making the question of the evolutionary forces driving these ontogenetic changes in distribution even more intriguing.
The role of wave-induced pressure fluctuations in the transfer processes across an air–water interface
Authors: Papadimitrakis Yiannis Alex , Hsu En Yun , Street Robert L.
Published: April 2006

The structure of the pressure and velocity fields in the air above mechanically generated water waves was investigated in order to evaluate their contribution to the transfer of momentum and energy from wind to water waves. The measurements were taken in a transformed Eulerian wave-following frame of reference, in a wind-wave research facility at Stanford University.

The organized component of the fluctuating static pressure at the channel roof was found to contain contributions from both the sound field and the reflected water wave. The acoustic contributions were accounted for by appropriately correcting the pressure amplitude and phase (relative to the wave) and its contribution to the momentum and energy exchange. The wave-induced pressure coefficient at the fundamental mode shows in general an exponential decay behaviour with height, but the rate of decay is different from that predicted by potential-flow theory. The wave-induced pressure phase relative to the wave remains fairly constant throughout the boundary layer, except when the ratio of the wave speed to the freestream velocity, c/Uδ0 = 0.78 and 0.68. This phase difference was found to be about 130° during active wave generation, with the pressure lagging the wave. The momentum and energy transfer rates supported by the waves were found to be dominated by the wave-induced pressure, but the transfer of the corresponding total quantities to both waves and currents may or may not be so dominated, depending on the ratio c/Uδ0. The direct contribution of the wave-induced Reynolds stresses to the transfer processes is negligible.
Large-scale flow in turbulent convection: a mathematical model
Authors: Howard L. N. , Krishnamurti R.
Published: April 2006

A mathematical model of convection, obtained by truncation from the two-dimensional Boussinesq equations, is shown to exhibit a bifurcation from symmetrical cells to tilted non-symmetrical ones. A subsequent bifurcation leads to time-dependent flow with similarly tilted transient plumes and a large-scale Lagrangian mean flow. This change of symmetry is similar to that occurring with the advent of a large-scale flow and transient tilted plumes seen in laboratory experiments on turbulent convection at high Rayleigh number. Though not intended as a description of turbulent convection, the model does bring out in a theoretically tractable context the possibility of the spontaneous change of symmetry suggested by the experiments.

Further bifurcations of the model lead to stable chaotic phenomena as well. These are numerically found to occur in association with heteroclinic orbits. Some mathematical results clarifying this association are also presented.
On the existence of localized rotational disturbances which propagate without change of structure in an inviscid fluid
Authors: Moffatt H. K.
Published: April 2006

A wide class of solutions of the steady Euler equations, representing localized rotational disturbances imbedded in a uniform stream U0 is inferred by considering the process of magnetic relaxation to analogous magnetostatic equilibria. These solutions, which may be regarded as generalizations of vortex rings, are characterized by their streamline topology, distinct topologies giving rise to distinct solutions.

Particular attention is paid to the class of axisymmetric solutions described by Stokes stream function ψ(s, z). It is argued that the appropriate topological ‘invariant’ characterizing the flow is the function Vψ representing the volume inside toroidal surfaces ψ = const, in the region of closed streamlines where ψ > 0. This function is described as the ‘signature’ of the flow, and it is shown that in a certain sense, flows with different signatures are topologically distinct. The approach yields a method by which flows of arbitrary signature V(ψ) may in principle be found, and the corresponding vorticity ωφ = sFψ calculated.
Anisotropy of the temperature dissipation in a turbulent wake
Authors: Antonia R. A. , Browne L. W. B.
Published: April 2006

Measurements by Freymuth & Uberoi (1971) of the terms in the transport equation for the temperature variance in a plane turbulent wake indicated approximate equality for the three components of the temperature dissipation, thus indicating isotropy for that quantity. This result was in sufficient disagreement with the results obtained in several other turbulent shear flows to warrant further measurements of the temperature dissipation in the wake. The present measurements indicate that the dissipation is larger than the isotropic value by about 50 % near the wake centreline and nearly 100 % near the region of maximum production. The magnitude of this ratio is similar to that obtained in other turbulent shear flows. The present measured ratio of total dissipation to isotropic dissipation leads to a satisfactory closure of the temperature variance budget for our experiments and also for the plane-wake measurements of Fabris (1974). It is concluded that the temperature dissipation is not isotropic.
Nonlinear waves in compacting media
Authors: Barcilon Victor , Richter Frank M.
Published: April 2006

An investigation of the mathematical model of a compacting medium proposed by McKenzie (1984) for the purpose of understanding the migration and segregation of melts in the Earth is presented. The numerical observation that the governing equations admit solutions in the form of nonlinear one-dimensional waves of permanent shape is confirmed analytically. The properties of these solitary waves are presented, namely phase speed as a function of melt content, nonlinear interaction and conservation quantities. The information at hand suggests that these waves are not solitons.
Oscillatory instabilities of convection rolls at intermediate Prandtl numbers
Authors: Bolton E. W. , Busse F. H. , Clever R. M.
Published: April 2006

The analysis of the instabilities of convection rolls in a fluid layer heated from below with no-slip boundaries exhibits a close competition between various oscillatory modes in the range 2 [lsim ] P [lsim ] 12 of the Prandtl number P. In addition to the even-oscillatory instability known from earlier work two new instabilities have been found, each of which is responsible for a small section of the stability boundary of steady rolls. The most interesting property of the new instabilities is their close relationship to the hot-blob oscillations known from experimental studies of convection. In the lower half of the Prandtl-number range considered the B02-mode dominates, which is characterized by two blobs each of slightly hotter and colder fluid circulating around in the convection roll in a spatially and time-periodic fashion. At higher Prandtl numbers the BE 1-mode dominates, which possesses one hot blob (and one cold blob) circulating with the convection velocity. Just outside the stability boundary there exist other growing modes exhibiting three or four blobs which may be observable in experiments.
The rapid expansion of a supersonic turbulent flow: role of bulk dilatation
Authors: Dussauge J. P. , Gaviglio J.
Published: April 2006

The rapid expansion of a turbulent boundary layer in supersonic flow is studied analytically and experimentally. Emphasis is placed on the effect of bulk dilatation on turbulent fluctuations. The hypotheses made in the analysis are similar to those in the rapid distortion theory and are used to simplify second-order closures. By assuming that the fluctuating velocity is solenoidal an extension of classical subsonic models is proposed. A new variable is defined, which takes into account the mean density variations, and behaves like the Reynolds stress tensor in subsonic flows with weak inhomogeneities and a weak dissipation rate. The results of the analysis are compared with turbulence measurements performed in a supersonic boundary layer subjected to an expansion fan. The proposed approximations describe correctly the evolution of turbulence intensities: bulk dilatation contributes predominantly to the Reynolds stress evolution. The boundary layer is ‘relaminarized’ by the expansion. Downstream of the latter, the layer returns to equilibrium. Measurements show that the turbulence decays slowly in the outer layer and increases rapidly in the inner layer.
Large-scale vortex structures in turbulent wakes behind bluff bodies. Part 2. Far-wake structures
Authors: Steiner T. R. , Perry A. E.
Published: April 2006

An investigation of a selection of high-Reynolds-number bluff-body flows was conducted. Here in Part 2 phase-averaged velocity-field results will be presented for several far-wake flows generated by nominally two-dimensional and three-dimensional bodies. In these far-wake flows the shed vortices have approached a nearly constant convection velocity. Some mean velocity and phase-averaged and global Reynoldsstress measurements are also presented. The turbulent wake of a lift-producing three-dimensional body has been examined. Also included are the phase-averaged wake patterns behind a flapping flag and a windmill. The topological structure of these patterns is discussed and a preliminary classification of wake patterns is presented.
On the ability of drops to stick to surfaces of solids. Part 3. The influences of the motion of the surrounding fluid on dislodging drops
Authors: Dussan V. E. B.
Published: April 2006

The ability of a drop to stick to a solid surface is investigated when the surrounding fluid is in motion. The specific problem analysed consists of a small drop on a planar surface immersed in a second immiscible fluid which is flowing parallel to the solid surface at a constant rate of strain. An expression is obtained, in terms of experimentally measurable quantities, for the value of the rate of strain beyond which the drop cannot maintain contact with a fixed position on the solid. The most limiting restrictions assumed in the analysis are that both the advancing contact angle and the contact angle hysteresis must be small.
Vortex-driven acoustically coupled combustion instabilities
Authors: Poinsot Thierry J. , Trouve Arnaud C. , Veynante Denis P. , Candel Sebastien M. , Esposito Emile J.
Published: April 2006

Combustion instability is investigated in the case of a multiple inlet combustor with dump. It is shown that low-frequency instabilities are acoustically coupled and occur at the eigenfrequencies of the system. Using spark-schlieren and a special phase-average imaging of the C2-radical emission, the fluid-mechanical processes involved in a vortex-driven mode of instability are investigated. The phase-average images provide maps of the local non-steady heat release. From the data collected on the combustor the processes of vortex shedding, growth, interactions and burning are described. The phases between the pressure, velocity and heat-release fluctuations are determined. The implications of the global Rayleigh criterion are verified and a mechanism for low-frequency vortex-driven instabilities is proposed.
The propagation of short surface waves on longer gravity waves
Authors: Longuet-Higgins M. S.
Published: April 2006

To understand the imaging of the sea surface by radar, it is useful to know the theoretical variations in the wavelength and steepness of short gravity waves propagated over the surface of a train of longer gravity waves of finite amplitude. Such variations may be calculated once the orbital accelerations and surface velocities in the longer waves have been accurately determined – a non-trivial computational task.

The results show that the linearized theory used previously for the longer waves is generally inadequate. The fully nonlinear theory used here indicates that for longer waves having a steepness parameter AK = 0.4, for example, the short-wave steepness can be increased at the crests of the longer waves by a factor of order 8, compared with its value at the mean level. (Linear theory gives a factor less than 2.)

The calculations so far reported are for free, irrotational gravity waves travelling in the same or directly opposite sense to the longer waves. However, the method of calculation could be extended without essential difficulty so as to include effects of surface tension, energy dissipation due to short-wave breaking, surface wind-drift currents, and to arbitrary angles of wave propagation.
The response of a stratified rapidly rotating flow to a pulsating topography
Authors: Brown S. N. , Cheng H. K.
Published: April 2006

A theoretical study is made of the disturbance produced by an oscillating, shallow topographical feature in horizontal relative motion in a rapidly rotating, linearly stratified, unbounded fluid. For a sinusoidal surface oscillation, an explicit solution is obtained in terms of wavenumber spectra of the topography. The oscillating far-field behaviour is shown to consist of a large-scale, cyclonic component above the topography and a system of inertial waves behind the caustics, which spreads predominantly in the downstream direction. A significant property of the flow field is its dependence on a frequency threshold familiar from classical works on internal gravity waves in the absence of rotation, determined by the Brunt-Väisälä value. When the frequency is supercritical, a prominent circle of maximum disturbance appears in the far field, which provides the transition boundary between two distinct cyclonic structures and an upstream barrier to the propagating waves ahead of the obstacle. The circle has a radius depending on the relative magnitude of the pulsating frequency and the Brunt-Väisälä value, and is distinctly marked also by a phase jump in pressure and velocities. These features are substantiated by numerical examples of the full solution at a large but finite distance above the obstacle at supercritical frequencies. The circle of maximum disturbance signifies a preferential direction for energy propagation unaccounted for by group velocity. Its relation to the classical result of Görtler in the homogeneous case and that in the classical internal-gravity-wave theory are examined.
On the reflection of a train of finite-amplitude internal waves from a uniform slope
Authors: Thorpe S. A. , Thorpe S. A. , Haines A. P.
Published: April 2006

The reflection of a train of two-dimensional finite-amplitude internal waves propagating at an angle β to the horizontal in an inviscid fluid of constant buoyancy frequency and incident on a uniform slope of inclination α is examined, specifically when β > α. Expressions for the stream function and density perturbation are derived to third order by a standard iterative process. Exact solutions of the equations of motion are chosen for the incident and reflected first-order waves. Whilst these individually generate no harmonics, their interaction does force additional components. In addition to the singularity at α = β when the reflected wave propagates in a direction parallel to the slope, singularities occur for values of α and β at which the incident-wave and reflected-wave components are in resonance; strong nonlinearity is found at adjacent values of α and β. When the waves are travelling in a vertical plane normal to the slope, resonance is possible at second order only for α < 8.4° and β < 30°. At third order the incident wave is itself modified by interaction with reflected components. Third-order resonances are only possible for α < 11.8° and, at a given α, the width of the β-domain in which nonlinearities connected to these resonances is important is much less than at second order. The effect of nonlinearity is to reduce the steepness of the incident wave at which the vertical density gradient in the wave field first becomes zero, and to promote local regions of low static stability remote from the slope. The importance of nonlinearity in the boundary reflection of oceanic internal waves is discussed.

In an Appendix some results of an experimental study of internal waves are described. The boundary layer on the slope is found to have a three-dimensional structure.
Compressible flow past a contour and stationary vortices
Authors: Barsony-Nagy A. , Er-El J. , Yungster S.
Published: April 2006

The Rayleigh-Janzen expansion method is extended to plane and steady flows which contain one or more point vortices interacting with a smooth or sharp-edged obstacle. A uniformly valid approximate solution of the compressible-flow equations is deduced by applying a perturbation method and by using matched asymptotic expansions to solve the resulting singular perturbation problem. The method yields compressibility corrections for the vortex positions and for the velocities. Results are presented for the flow past a circle and a pair of symmetric vortices (Föppl's flow). They show that the compressibility effects are substantial and are consistent with experimental data.
Forces on a slender ship advancing near the critical speed in a wide canal
Authors: Mei Chiang C. , Choi Hang S.
Published: April 2006

Employing matched asymptotics, we extend the recent theory of Mei (1986) to study the phenomenon of upstream influence by a slender ship moving near the critical speed. For a special class of channel width and ship slenderness, it is shown that the response on the sea surface is essentially one-dimensional with the wave crests perpendicular to the ship's axis. In particular, solitons are radiated upstream. The hydrodynamic pressure on the ship, as well as the total sinkage force, wave resistance and trimming moment are calculated. These forces are functions of time despite the constant speed of the ship. The sinkage and trim for a ship model fixed on an advancing carriage are computed and show rapid variations across the critical speed as in the reported experiments of Graff, Kracht & Weinblum (1964). Because of the assumed slenderness of the ship, this theory does not predict two-dimensional waves in the wake. Nevertheless, there is crude agreement in the time-averaged hydrodynamic forces between theory and experiment.
Separation and free-streamline flows in a rotating fluid at low Rossby number
Authors: Page Michael A.
Published: April 2006

The flow past a circular cylinder in a rotating frame is examined when the Rossby number Ro is O(E½), where E is the Ekman number. Previous studies of the configuration have shown that, provided the ratio Ro/E½ is less than a certain critical value, the flow around the cylinder is determined by the classical potential-flow solution. However, once Ro/E½ is greater than that critical value the E1/4 layer on the surface of the cylinder, which is rather like a boundary layer in a high-Reynolds-number non-rotating fluid, can separate from the cylinder and distort the potential flow. In this study the form of the flow once separation has occurred is examined using a method analogous to the Kirchhoff free-streamline theory in a non-rotating fluid. The results are compared with published experimental and numerical data on the flow for various values of Ro/E½.
Shear-flow instability due to a wall and a viscosity discontinuity at the interface
Authors: Hooper A. P. , Boyd W. G. C.
Published: April 2006

Consider the Couette flow of two superposed fluids of different viscosity with the depth of the lower fluid bounded by a wall and the interface while the depth of the upper fluid is unbounded. The linear instability of this flow configuration is studied at all values of flow Reynolds number and disturbance wavelength using both asymptotic and numerical methods. Three distinct forms of instability are found which are dependent on the magnitude of two dimensionless parameters β and (α R)1/3, where β is a dimensionless wavenumber measured on a viscous lengthscale, α is a dimensionless wavenumber measured on the scale of the depth of the lower fluid and R is the Reynolds number of the lower fluid. At large β there is the short-wave instability found previously by Hooper & Boyd (1983). At small β and small (αR)1/3 there is the long-wave instability first discovered by Yih. At small β and large (αR)1/3 there is a new type of instability which arises only if the kinematic viscosity of the lower bounded fluid is less than the kinematic viscosity of the upper fluid.
On the breakdown of the steady and unsteady interacting boundary-layer description
Authors: Henkes R. A. W. M. , Veldman A. E. P.
Published: April 2006

It is known that the classical boundary-layer solution breaks down through the appearance of the Goldstein singularity in a steady solution or Van Dommelen's singularity in an unsteady solution. Interaction between the inviscid flow and the boundary layer removes the Goldstein singularity, until a new critical parameter is reached, corresponding to a marginal separation in the asymptotic triple-deck description. In earlier studies instabilities were encountered in interacting boundary-layer calculations of steady flow along an indented plate, which might be related to the breakdown of the marginal separation. The present study identifies them as numerical. Further, until now it was unknown whether the unsteady interacting boundary-layer approach would remove Van Dommelen's singularity in the classical boundary layer around an impulsively started cylinder. It is shown here that its appearance is at least delayed. The calculations show the experimentally known individualization of a vortex, after which the solution grows without reaching a steady limit; a process that is likely to be related to dynamic stall.
A linear analysis of rotating stratified flow past a circular cylinder on a β-plane
Authors: Merkine Lee-Or
Published: April 2006

A linear analysis of rotating stratified quasi-geostrophic flow past a circular cylinder on a β-plane is performed for moderate stratification, i.e. for σS = O(E½), covering effectively the range $E^{\frac{2}{3}} \ll \sigma \ll 1$, and for strong stratification such that σS = O(1). E [Lt ] 1 is the Ekman number and σS is the product of the Prandtl number and the inverse rotational Froude number. The parameter β measures the importance of the production of relative vorticity by meridional motion. The analysis pivots about a range of β which constrains the interior motion to follow geostrophic contours. For moderate stratification β = O(E1/4), covering effectively the range E½ [Lt ] β [Lt ] E⅛, while for strong stratification E [Lt ] β [Lt ] 1. The dominance of β in the interior is responsible for creating a narrow intense boundary layer along the eastern sector of the cylinder and an extensive blocked flow region surrounded by intense free shear layers west of the cylinder. These narrow regions which channel horizontally O(1) mass flux communicate through corner-like regions centred about the extreme meridional locations of the cylinder. The effect of stratification is to shear the flow vertically and to induce counter-flows laterally. When the stratification is strong the z-dependence is parametric. Nonlinear effects can be ignored when the Rossby number, ε, satisfies the constraints $\epsilon \ll E^{\frac{11}{12}}$ for moderate stratification and $\epsilon \ll \beta^{\frac{1}{7}} E^{\frac{6}{7}}$ for strong stratification. When expressed in terms of the Reynolds number, Re = ε/E, smallness of nonlinear effects can be assured also for high-Reynolds-number flows.
Observations of dispersion of entrained fluid in the self-preserving region of a turbulent jet
Authors: Shlien D. Joseph
Published: April 2006

Ambient fluid of a submerged water jet was continuously tagged with fluorescent dye at a point outside the turbulent region (at 33 jet nozzle diameters from the jet exit). This made it possible to follow the tagged entrained fluid to 73 jet diameters downstream of the exit, a distance unattainable by other methods. The dispersion of the tagged fluid in a plane containing the jet axis and the tagging source was observed and recorded using photography and simple digital image-processing techniques. Most of the entrainment activity appeared to be the result of engulfment by the large-scale structures over an axial distance of ± 1.7B from the source where B is the half-peak velocity radius. The entrained fluid crossed the jet centreline within a downstream distance of Δx = 1.5B.

Downstream of the entrainment region, the spread rate of the tagged entrained fluid was close to that of the turbulent jet fluid. However, the peak mean concentration of the tagged entrained fluid was located near the r/x = 0.1 line closest to the tagging source and shifted very slowly towards the jet centreline. A self-preserving distribution of the mean concentration appears to have been approached after a distance of 6B downstream from the tagging source but further verification is needed owing to experimental uncertainties.

A small fraction of the tagged entrained fluid was found on the side of the jet remote from the tagging source. On rare occurrences, tagged entrained fluid was observed at the interface most remote from the source.