Classical asperity theories predict, in qualitative agreement with experimental observations, that adhesion is always destroyed by roughness except if the roughness amplitude is extremely small, and ...the materials are particularly soft. This happens for all fractal dimensions. However, these theories are limited due to the geometrical simplification, which may be particularly strong in conditions near full contact. We therefore introduce a simple model for adhesion which aims at being rigorous near full contact, where we postulate there are only small isolated gaps between the two bodies, as an extension of the adhesive-less solution proposed recently by Xu, Jackson, and Marghitu (XJM model) (Xu et al., 2014) 1, using the JKR theory for each gap. The results confirm recent theories in that we find an important effect of the fractal dimension. For D<2.5, the case which includes the vast majority of natural surfaces, there is an expected strong effect of adhesion. Only for large fractal dimensions, D>2.5, it seems that for large enough magnifications a full fractal roughness completely destroys adhesion. These results are partly paradoxical since strong adhesion is not observed in nature except in special cases.
•We introduce a simple model for adhesion rigorous near full contact.•Solution is found postulating constant stress intensity factor on edge of isolated gaps.•Results confirm some previous theories: for fractal dimension D<2.5, strong effect of adhesion.•However strong adhesion is not commonly observed in nature.
The classical Fuller and Tabor theory of rough surface adhesion is reviewed, and its limited applicability noted. New results using an extension of the JKR adhesion theory to include the effect of ...van der Waals adhesion forces are described. These show the influence of the Tabor parameter μ: moderate values of µ (µ<100) lead to increased forces during loading, and so are found to predict much lower hysteresis losses. A further extension is to replace the GW surface roughness model used by Fuller and Tabor by a model based on the Nayak model of a surface as a random field, as in the Bush, Gibson and Thomas (BGT) theory of non-adhesive contact. The results are qualitatively the same, and the differences may well be largely due to the necessary redefinition of the adhesion index using the rms profile curvature in place of the asperity radius of curvature used in the GW model. `
Boron (B) deficiency is an agricultural problem that causes significant yield losses in many countries. B transporters (
BOR
s) are responsible for B uptake and distribution and play important roles ...in yield formation. A comprehensive analysis of the
BOR
family members in common wheat is still lacking. In the present study, to clarify the molecular characterization and response to B status, genome-wide
TaBOR
genes and expression patterns were investigated. Fourteen
TaBOR
genes were identified in common wheat by a homology search. The corresponding phylogenetic tree indicated that 14
TaBOR
genes were separately classified into subfamilies of
TaBOR1
,
TaBOR3
, and
TaBOR4
. All
TaBOR
genes had 12–14 extrons and 11–13 introns. Most
TaBOR
proteins contained 10 conserved motifs, and motifs 1, 2, 3, 4, and 6 constituted the conserved bicarbonate (HCO
3
–
) domain. Fourteen
TaBOR
genes were mapped on 13 chromosomes mainly distributed in the first, third, fifth, and seventh homologous groups. The promoters of
TaBOR
genes consisted of phytohormones, light responses, and stress-related cis-elements. GO analysis indicated that
TaBOR
genes were enriched in terms of transmembrane transport and ion homeostasis.
TaBOR
genes showed diverse expression profiles in different tissues. The members of the
TaBOR1
subfamily showed high expression in grains, leaves, roots, stems, and spikes, but members of the
TaBOR4
subfamily were highly expressed only in spikes and grains. RT–qPCR indicated that
TaBOR1-5A
,
TaBOR1-5B
, and
TaBOR1-5D
were induced by low B concentrations and had much higher expression in roots than in shoots.
TaBOR3-3A
,
TaBOR3-3B
,
TaBOR3-3D
,
TaBOR4-1A
,
TaBOR4-1B
,
TaBOR4-1D
, and
TaBOR3-4B
were induced by low and high B concentrations and had high expression in roots and shoots.
TaBOR3-4D
and
TaBOR3-7B
were upregulated by low and high B concentrations, respectively, but had expression only in roots. Our results provide basic information on the
TaBOR
family, which is beneficial for elucidating the functions of
TaBOR
genes to overcome the problem of B deficiency.
Abstract Background Pelvic floor disorders are a group of disorders affecting the pelvic floor that include clinically definable conditions such as pelvic organ prolapse, urinary incontinence and ...fecal incontinence. These conditions silently affect millions of women worldwide and related problems are not well disclosed by women due to associated social stigma or lack of access to services in developing countries. Thus, the magnitude and related burden of these conditions vary, and little is known about them. This study was conducted to assess the magnitude and associated factors of symptomatic pelvic floor disorders in Debre Tabor town, Northwest, Ethiopia, from May 30-July 30, 2020. Method A community-based cross-sectional study was conducted on child bearing women (> 15 years) who resided in Debre Tabor Town from May 30-July 30, 2020. The participants were selected through multistage systematic random sampling. The data were collected via a structured questionnaire through face-to-face interviews, entered into Epi-info-7.2, and subsequently analyzed using SPSS version 20. The prevalence of pelvic floor disorders was presented along with the 95% CI. Results A total of 402 women participated in this study, 59 (14.7%; 95% CI; 11.4, 18.2) of whom reported one or more types of pelvic floor disorders. The most prevalently reported pelvic floor disorders were pelvic organ prolapse (13.9%; 95% CI: 10.9, 17.4), urinary incontinence (10.9%; 95% CI: 7.4, 9.2) and fecal incontinence (7.7%; 95% CI: 5.2, 10.2). Additionally, aging, multiparity and having early marriage (< 18 yrs.) were identified as potential risk factors associated with pelvic floor disorders. Conclusions The prevalence of symptomatic pelvic floor disorders in the current study was high. Thus, early detection, preventive and treatment strategies should be considered. In addition, it is better to educate the community and women on the association of early marriage and multiparty with PFDs.
Recently Guduru and coworkers have demonstrated with neat theory and experiments that both increase of strength and of toughness are possible in the contact of a rigid sphere with concentric single ...scale of waviness, against a very soft material. The present note tries to answer the question of a multiscale enhancement of adhesion, considering a Weierstrass series to represent the multiscale roughness, and analytical results only are used. It is concluded that the enhancement is bounded for low fractal dimensions but it can happen, and possibly to very high values, whereas it is even unbounded for high fractal dimensions, but it is also much less likely to occur, because of separated contacts.
•Increase of strength and of toughness are possible in the contact of rough bodies.•For multiscale enhancement of adhesion, this paper considers a Weierstrass series.•Enhancement is bounded for low fractal dimensions but it can happen, and possibly to very high values.•Enhancement is even unbounded for high fractal dimensions, but it is also much less likely to occur, because of separated contacts.
The old asperity model of Fuller and Tabor had demonstrated almost 50 years ago surprisingly good correlation with respect to quite a few experiments on the pull-off decay due to roughness of rubber ...spheres against roughened Perspex plates. We revisit here some features of the Fuller and Tabor model in view of the more recent theories and experiments, finding good correlation can be obtained only at intermediate resolutions, as perhaps in stylus profilometers. In general we confirm qualitatively the predictions of the Persson & Tosatti and Bearing Area Model of Ciavarella, as stickiness depends largely on the long wavelength content of roughness, and not the fine features.
•The old asperity model of Fuller and Tabor had demonstrated surprisingly good correlation.•However, asperity models today are believed to be largely ill-conditioned.•Good correlation can be obtained with the Fuller and Tabor model only at intermediate resolutions.•Stickiness depends largely on the long wavelength content of roughness, and not the fine features.•Multi-instruments measurements should hopefully not be needed.
Początki produkcji tramwajów na obszarze Ukrainy to okres międzywojenny, a trolejbusów – koniec lat pięćdziesiątych XX wieku. Jednakże wraz z masowymi dostawami importowanego taboru z Rosji i ...Czechosłowacji produkcję tych środków transportu na Ukrainie wstrzymano. Na początku lat 90. XX wieku – z powodu kryzysu ekonomicznego i problemów finansowych – dostawy zagraniczne uległy znacznemu zmniejszeniu. Sytuacja przedsiębiorstw tramwajowych i trolejbusowych pogorszyła się wraz z rozpadem ZSRR, kiedy to uległy rozerwaniu więzi gospodarcze nie tylko pomiędzy państwami Europy Środkowej i Wschodniej, ale również pomiędzy byłymi sowieckimi republikami. W tych trudnych ekonomicznie warunkach podjęto decyzję o wznowieniu na Ukrainie produkcji tramwajów i trolejbusów. Artykuł ma na celu analizę sytuacji taborowej komunikacji tramwajowej i trolejbusowej na Ukrainie po 25 latach od momentu odzyskania niepodległości, poprzez porównanie dwóch aspektów jej funkcjonowania: ukraińskiego rynku producentów taboru tramwajowego i trolejbusowego oraz sytuacji taborowej przedsiębiorstw. Jako obszar badań przyjęto granice Ukrainy sprzed 2014 roku. Badania mają charakter podstawowy i opierają się w dużej mierze na materiale zebranym przez autorów. W artykule przeanalizowano produkcję taboru na Ukrainie po 1991 roku – nie tylko opisano produkowane marki i modele, ale również przygotowano zestawienia statystyczne dotyczące wielkości produkcji i jej odbiorców. Sytuację na rynku producentów taboru porównano z sytuacją taborową tamtejszych przedsiębiorstw. Badania potwierdziły, że mamy do czynienia z kryzysem systemowym. Komunalne przedsiębiorstwa tramwajowe i trolejbusowe każdego roku generują straty i coraz większe zadłużenie. Nowy tabor kupowany jest nieregularnie i w niewielkich ilościach, co ogranicza liczbę potencjalnych dostawców, a w dodatku przy wyborze najkorzystniejszej oferty preferowany jest rodzimy producent. Tym samym nie musi on być konkurencyjny cenowo, jakościowo i technologicznie, co tylko zwiększa jego dystans rozwojowy w stosunku do czołowych producentów taboru w Europie. A z uwagi na relatywnie niską jakość produktów ze swojego portfolio musi utrzymywać się wyłącznie ze skromnych zleceń krajowych.
Buhe festival is also called Debre Tabor festival. It is one of the most famous intangible cultural heritage events in Ethiopia. It was only a few decades ago that event tourism became established in ...both the tourism industry and in the research community, so that subsequent growth of this sector can only be described as spectacular. The festival is becoming highly celebrated at Debre Tabor town, Ethiopia. However, its potential, value and opportunities haven t been studied so far. Thus, the objective of the study is to explore the practices of safeguarding Buhe festival for event tourism development. The study used descriptive research design and employed a qualitative approach. The target population were religious leaders, culture and tourism experts, the local community and the researchers themselves. Data instruments were interviews, observation and secondary data like document analysis. The collected data were analysed through thematic analysis method. Findings revealed that Buhe festival in Debre Tabor is endowed with immense potential in the form of cultural treasures, Debre Tabor Mountain, traditional songs with awesome poems, local traditional costumes, religious ceremonies, ancient history, religious institutions and others. The main values of the festival are socio-cultural, but also economic, creating a good image of the destination and its historical and religious values. Further opportunities include the use of Gafat Industrial villages and the ancient palace of Emperor Yohannes IV, celebrating the birth date of Menelik the Second and his beloved wife, and increased government attention for event tourism. Generally, tourism and its related stakeholders should work together to explore the potentials of the festival, to use the values of the festival and to strength the opportunities it is endowed with for the sake of event tourism development at the study area.
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