Smooth Body Research Articles

The support of mixed area measures involving a new class of convex bodies

Mixed volumes in n-dimensional Euclidean space are functionals of n-tuples of convex bodies K,L,C1,…,Cn−2. The Alexandrov–Fenchel inequalities are fundamental inequalities between mixed volumes of convex bodies. As very special cases they cover or imply many important inequalities between basic geometric functionals. A complete characterization of the equality cases in the Alexandrov–Fenchel inequality remains a challenging open problem. Major recent progress was made by Yair Shenfeld and Ramon van Handel [13,14], in particular they resolved the problem in the cases where C1,…,Cn−2 are polytopes, zonoids or smooth bodies (under some dimensional restriction). In [6] we introduced the class of polyoids, which are defined as limits of finite Minkowski sums of polytopes having a bounded number vertices. Polyoids encompass polytopes, zonoids and triangle bodies, and they can be characterized by means of generating measures. Based on this characterization and Shenfeld and van Handel's contribution (and under a dimensional restriction), we extended their result to polyoids (or smooth bodies). Our previous result was stated in terms of the support of the mixed area measure associated with the unit ball Bn and C1,…,Cn−2. This characterization result is completed in the present work which more generally provides a geometric description of the support of the mixed area measure of an arbitrary (n−1)-tuple of polyoids (or smooth bodies). The result thus (partially) confirms a long-standing conjecture by Rolf Schneider in the case of polyoids, and hence in particular it covers the case of zonoids and triangle bodies.

Volumetric Reconstruction Of Stagnated Wake Structures In Adverse Pressure Gradient

To gather insights about turbulent structures of a wake in adverse pressure gradient, a wind tunnel model is investigated with PIV methods. A flat plate of L = 1.058 m at zero angle of attack is placed in the MUB wind tunnel at TU Braunschweig. The wake convects downstream into a carefully designed diffuser, where it undergoes a pressure increase of ∆c p = +0.6. Wakes, with the common example of a cylinder shedding van-Karman vortices, are generally prone to instability. The wake instability of the sharp-edged plate is attenuated by the adverse pressure gradient, manifesting in large coherent structures that carry up to 37 % of the turbulent kinetic energy. While the primary shedding motion is effectively a quasi-2D motion, a secondary mode of is also observed: Over the span S = 1.3 m of the wake, it organizes in three distinct cells. Their motion is similar to "owl-eyes", that are known to appear on separated flow over smooth 2D bodies. The presence of these modes reduces the average flow velocity in the wake centre up to stagnation in the mean sense. Because stagnation and shedding does occur far away from any solid surfaces, this test case offers excellent observability of the phenomenon with PIV methods. RANS results of this setup cannot predict the flow stagnation accurately. Because the shedding frequency is low compared to freestream velocity, scale and time resolving IDDES results need to run many convective time units until the observed instability develops. While the original goal of observing small scale turbulent wake structures is compromised by the large shedding modes, the observation gives an insight on wake-bursting phenomena that occur on multi-element high-lift devices. The mode shedding and consequent wake stagnation is sensitive to the Reynolds-number (Re = [1.6 ... 3.2] · 10 6 ) as well as to the initial boundary layer thickness of the flat plate.

The effect of a textured surface in the form of triangular prisms on the occurrence and development of cavitation behind the cylinder in microchannels

Cavitation flow in a microchannel behind a cylinder with a smooth and textured surface is investigated using mathematical modeling methods. The textured cylinder has 72 triangular prisms on its surface. The height of the prism, normal to the surface of the bluff body, was 100 nm. Profiles of the flow velocity and volume fraction of vapor are constructed. The monitoring of the velocity and pressure at five points behind both the smooth and the textured cylinder was carried out, while the inlet pressure changed up to 30 bars. It is shown that there is no restructuring of the vortex street to a symmetrical form at quite high-pressure values at the inlet to the channel for a rough cylinder. Namely, roughness prevents the flow stabilization. A pressure jump in the microchannel is observed when a cavity appears with a uniform increase in the flow rate. Two pulsation frequencies are determined for each of the flow modes. The first pulsation frequency ranges from 480 to 2200 Hz and is associated with the formation of cavitation. The second pulsation frequency is associated with the hydrodynamic flow around the cylinder and its values range from 26 to 95 kHz. An increase in surface roughness leads to a growth of the cavitation pulsation frequency and intensifies cavitation. At that, the velocity pulsations in the flow before the onset of cavitation increase, and the frequency of hydrodynamic pulsations after its onset decrease. The paper provides an analysis of the drag coefficient of a hydraulic section with rough and smooth cylindrical bluff bodies. The effect of roughness on the change in the hydrodynamic characteristics of the flow is described.

Variational Worn Stones

We introduce an evolution model à la Firey for a convex stone which tumbles on a beach and undertakes an erosion process depending on some variational energy, such as torsional rigidity, a principal Dirichlet Laplacian eigenvalue, or Newtonian capacity. Relying on the assumption of the existence of a solution to the corresponding parabolic flow, we prove that the stone tends to become asymptotically spherical. Indeed, we identify an ultimate shape of these flows with a smooth convex body whose ground state satisfies an additional boundary condition, and we prove symmetry results for the corresponding overdetermined elliptic problems. Moreover, we extend the analysis to arbitrary convex bodies: we introduce new notions of cone variational measures and we prove that, if such a measure is absolutely continuous with constant density, the underlying body is a ball.

Pathologies in the Asymptotics of low-Froude Free-surface Waves Over Smooth Bodies

In the study of low-speed or low-Froude flows of a potential gravity-driven fluid past a wave-generating object, the traditional asymptotic expansion in powers of the Froude number predicts a waveless free-surface at every order. This is due to the fact that the waves are, in fact, exponentially small and beyond-all-orders of the naive expansion. The theory of exponential asymptotics indicates that such exponentially-small water waves are switched-on across so-called Stokes lines—these curves partition the fluid-domain into wave-free regions and regions with waves. In prior studies, Stokes lines are associated with singularities in the flow field, such as stagnation points, or corners of submerged objects or rough beds. In this work, we present a smoothed geometry that was recently highlighted by Pethiyagoda et al. [Int. J. Numer. Meth. Fluids. 2018; 86:607–624] as capable of producing waves, yet paradoxically exhibiting no obvious Stokes line according to conventional exponential asymptotics theory. In this work, we demonstrate that the Stokes line for this smooth geometry originates from an essential singularity at infinity in the analytic continuation of free-surface quantities. We discuss some of the difficulties in extending the typical methodology of exponential asymptotics to general wave-structure interaction problems with smooth geometries.

Two new ant species of the genus Leptogenys (Hymenoptera, Formicidae) from Hainan, China, with a key to the known Chinese species.

Two new species of ponerine ants from Hainan Province, China, Leptogenyshainanensissp. nov. and L.zhouisp. nov., are delineated and depicted based on the worker caste. Leptogenyshainanensissp. nov. belongs to the L.leleji species group, with mandibles elongate, slender and curved, lacking a distinct masticatory margin. On the other hand, L.zhouisp. nov. belongs to the L.crassicornis species group, distinguished by its square head, smooth body, mandibles with a dentate masticatory margin, and short antennae. A key to workers for the known species of Leptogenys in China are provided and a map is provided for the newly described species.

Endoscopic Removal of Gastric Foreign Bodies with a Bottle Liner in 12 Dogs (2020-2023).

Endoscopy is widely used to remove gastric foreign bodies using grasping forceps and loop snares to manipulate and retrieve the foreign material. However, as not all foreign bodies can be removed using conventional endoscopic techniques, this case series describes the use of bottle liners for the removal of gastric foreign bodies in 12 dogs between 2020 and 2023. A 4 oz bottle liner (Drop-Ins) was placed at the end of the endoscope and pushed into the stomach. With the help of forceps introduced into the operating channel, the foreign body was pushed into the bottle liner. The bottle liner containing the foreign body was then extracted with the help of traction threads. The technique was used as the initial retrieval method in 5 dogs because of smooth (i.e., difficult to grasp) or sharp (i.e., that may damage the digestive tract mucosa during removal) foreign bodies and as a rescue procedure in 7 dogs. Foreign body retrieval was successful in all 12 dogs, with minor complications reported in 5 dogs (erosions and bleeding of the gastroesophageal sphincter). The use of a bottle liner represents an affordable alternative to gastrotomy when foreign bodies cannot be grasped with forceps or snares.

An examination of the status, contexts of anatomical body donation, and perspectives in China

Body donation is a valuable resource in medical education, research, clinical diagnosis, and treatment. Consequently, donors are honored as “Silent Mentors” in Chinese medical schools. This article briefly reviews the history, current status, and strategies to promote body donation in China (excluding data from Hong Kong, Macao, and Taiwan regions) and discusses the problems encountered in body donation work in China. After establishing the People’s Republic of China in 1949, the central government issued regulations on the use of dissected bodies. In 2001, the “Shanghai Regulations on Body Donation” were officially implemented and became China’s first local legislative regulation on body donation. Subsequently, local legislative regulations and rules on body donation were issued in various regions to promote smooth and orderly body donation. There has been tremendous development in body donation in China for more than 40 years; however, the progress of this partial work has been uneven in various areas owing to the influence of traditional ethical concepts. It is, therefore, imperative to legislate body donations at a national level. Raising the public’s scientific literacy and changing the traditional concept of funerals can create a positive social atmosphere for body donation, thus increasing the public’s awareness and willingness to donate their bodies. Donating the body at the end of life contributes to life science and medical causes and is a noble act worthy of praise.

Prediction of Oil Production in a Tight Sandstone Reservoir: Triassic Chang 9 Member, Jiyuan Area, Ordos Basin, NW China

Tight sandstone oil reservoirs in the Upper Triassic Yanchang Formation of the Ordos Basin are the most promising exploration and development fields owing to their huge production potential. Even though they have received considerable attention in recent years, common productivity prediction methods were not well applied during pre-development owing to their strong internal heterogeneity. In this study, the factors influencing oil production of the Chang 9 Member in the Jiyuan area were investigated and summarized based on drill cores, such as sediment characteristic analysis, lithofacies analysis, other analytical tests, and conventional logging curves. The findings show that fine-sandstone reservoirs with smooth sand body architectures are the main types of tight sandstone commercial oil reservoirs. Furthermore, having high porosity and oil content are prerequisites for commercial oil reservoirs, and the cumulative thickness of effective reservoirs serves as a crucial resource base for them. Through the analysis of logging curves, the relative center of gravity, deviation root of variance, petrophysical index, effective reservoir thickness, and evaluation indicator were used to predict daily oil production, thereby establishing the identification criteria for the ranking of tight sandstone oil reservoirs using logging. Then, the productivity of each reservoir in a single well was predicted by processing the log data from each well using the proposed method, and the productivity prediction results agreed well with the tested results of the perforated interval. This approach highlights the integrated influence of geological factors, physical properties, and the thickness scale of an effective reservoir, thereby improving the predictive capacity of logging curves. Additionally, the proposed methods significantly reduce the need for reservoir parameters better than previous ones, streamline operations, and improve practical applications.

Two new species of Hyalella (Amphipoda, Dogielinotidae) from the Humid Chaco ecoregion of Paraguay.

The freshwater amphipod genus Hyalella Smith, 1874 is widely distributed in the Neotropics, with several biogeographically restricted species and a high cryptic diversity throughout South America. Tens of species of Hyalella have been documented from nearby Brazil and Argentina, but no systematic record of the genus exists for Paraguay. Here we describe two new species of Hyalella: H.mboituisp. nov. and H.juliasp. nov. from the Ñeembucú wetlands of southwestern Paraguay. Hyalellamboituisp. nov. and H.juliasp. nov. are characterised by a dorsally smooth body, pigmented eyes, uropod 1 endopod with a curved seta, the dorsal margin of uropod 3 ramus without setae, and uropod 3 peduncle longer than wide and with six setae apically. The two species are distinguished by their diagnostic mouthparts, with a median serrated edge on the lacinia mobilis in H.mboituisp. nov. and two elongated lateral denticles with a serrated edge in H.juliasp. nov., and by the presence of a pronounced cup for the dactylus on gnathopod 2 in H.mboituisp. nov. In addition, they show differences in the number of articles on antennae 1 and 2, in the relative length of the pereiopods, and in the numbers and types of setae on their gnathopods and uropods 1-3. Hyalellamboituisp. nov. and H.juliasp. nov. represent the first taxonomically documented occurrence of Paraguayan freshwater amphipods. These new taxa attest to the largely unmapped species richness of freshwater invertebrates in the Humid Chaco of Paraguay. This potential biodiversity hotspot is currently under threat from land conversion, highlighting the need for more systematic studies and effective conservation of the local invertebrate biodiversity.

Description of one species of freshwater amphipod Hyalella (Crustacea, Peracarida, Hyalellidae) from the northwest region of the state of Rio Grande do Sul, Southern Brazil.

In this study, a new species of Hyalella is described from southern region of Brazil. Hyalella jaboticabensis n. sp. was recorded in the municipality of Jaboticaba, northwest region of state of the Rio Grande do Sul, southern Brazil. This species is characterized by showing smooth body surface, epimeral plates not acuminated, inner face of the gnathopod 1 with nine or ten serrate setae and some simple setae (six to eight), inner ramus of uropod 1 of males with one short curved seta, peduncle of the uropod 3 with six cuspidate setae with an accessory seta and two or three cuspidate setae on the rami, telson as long as wide (square) with six to eight short and long cuspidate setae with an accessory seta. This new description increases the Brazilian known diversity of species of Hyalella to 42 (25 to southern Brazilian region) and 108 species in the Americas. It is noting that it is crucial to know the complete diversity of Hyalella genus, and to consider conservation measures to protect species like H. jaboticabensis n. sp., endemic to two single small streams.

Cassidinidea andamanensis sp. nov., a new species of intertidal Sphaeromatidae (Crustacea: Isopoda) from the Andaman Islands, northern Indian Ocean.

Cassidinidea andamanensis sp. nov. was collected from intertidal habitats on the coast of South Andaman, Andaman Islands, India and is described and illustrated in detail. Cassidinidea andamanensis sp. nov. the second definitive record of the genus from India, is characterized by: smooth body surface, prominently convex epistome anterior margin, pleotelson dorsal smooth surface and the posterior margin is subtruncate and weakly convex with small setae, the appendix masculina posterior margin is narrowly rounded.

A new freshwater amphipod (Amphipoda, Gammaridae) from the Fakıllı Cave, Düzce Türkiye: Gammarus kunti sp. nov.

Aquatic species (such as fish, amphipods, isopods, hirudineans etc.) adapted to environmental conditions can live in caves connected to groundwater. The species of Niphargus and Gammarus are the most commonly encountered amphipods in caves. Türkiye is very rich in terms of karst areas and is home to more than 2000 known caves. Fakıllı Cave, located in Düzce Province in the Western Anatolian Region, has a length of 1071 m. A new amphipod species belonging to the Gammarus genus has been identified from the cave and named as Gammarus kuntisp. nov. Some of the characteristic features of the newly-identified species can be listed as “Medium-large size; smooth body, well-developed and reniform eyes; non-prolonged extremities; antennal gland cone is straight and long; second antenna with setose peduncular and flagellar segments; medial palmar spine present; posterior margin of pereopod 3 densely setose; anterior margins of pereopods 6 and 7 armed with spines only; epimeral plates not pointed”. Although the mentioned features are generally seen in epigean species, the members of this species were sampled from the dark zone of the Fakıllı Cave. The partial sequences of the COI (573 bp) and 28S (914 bp) genes of the newly-described species, Gammarus kuntisp. nov., were generated. The pairwise genetic distances between the new species, Gammarus kunti sp. nov. and other species ranged from a minimum of 16.23% (G. tumaf) to a maximum of 28.27% (G. roeselii) for the COI gene and a minimum of 0.88% (G. tumaf) to a maximum of 6.81% (G. balcanicus) for the 28S gene. Phylogenies generated by the NJ and ML methods, based on the combined data, assigned the new species as an independent lineage with high support values. In addition, the ASAP method identified the new species as a single MOTU independent of other species. G. tumaf and G. baysali are the sister taxa of G. kuntisp. nov. Detailed descriptions and drawings of the extremities of the male holotype and the female allotype are given and the morphology of the newly-identified species is compared with its relatives.

Research on the gel casting process and flexural strength of high-stability alumina ceramics

Gel casting is an advanced wet-forming method for ceramics. In this paper, Isoabm 104 is selected as the dispersant and gelation agent for gel casting. The optimization of gel casting slurry and the preparation of the green and sintered alumina bodies are investigated. TAC reduces the viscosity of the slurry significantly due to electrostatic interaction. Isopropanol alcohol and vacuum tank eliminates the slurry’s air bubbles, thus improving the density of green bodies. A staged drying process is necessary to produce smooth and defect-free green bodies. After optimization of the slurry formulation and gel casting process, alumina ceramics with a Weibull modulus of 11.1 are successfully prepared.

Morphological Characteristics and DNA Barcoding of the Rare Blanket Octopus Tremoctopus violaceus (Cephalopoda: Tremoctopodidae) in the Adriatic Sea

Tremoctopods are epipelagic argonautoid octopods characterized by their expanded dorsal webs and strong sexual size dimorphism, with dwarfed males. The scarcity of taxonomic features attributed to this genus presents a challenge, and there is growing evidence of species misidentification in Tremoctopus genus on a molecular level. In this study, we investigated four female specimens of blanket octopus Tremoctopus violaceus caught by purse seine fishing in the Central Eastern Adriatic Sea in 2019. Individuals had smooth, firm and muscular bodies, dark bluish purple on the dorsal and iridescent silvery on the ventral side, with dorsal mantle lengths of 113, 82, 80 and 78 mm. The constructed phylogenetic trees based on the 16S ribosomal RNA and cytochrome c oxidase subunit I sequences of investigated Adriatic specimens and publicly available sequences showed strong support for the T. violaceus clade, consisting of individuals collected from the Adriatic Sea, Mediterranean Sea and Atlantic Ocean, with the exclusion of Indo-Pacific clade most probably corresponding to T. gracilis. To fully understand the life-history traits of Tremoctopus species, future research should focus on DNA-based methods for correct species identification combined with morphological characters, geographic distribution and ecological information.

The remarkable Ponto-Caspian amphipod diversity of the lower Durso River (SW Caucasus) with the description of Litorogammarus dursi gen. et sp. nov.

The first insight into the unexpectedly diverse amphipod assemblage of the Durso River (Novorossiysk area) in the SW mountainous pre-Caucasian area is presented. The presence of six species is revealed, including three new records for the area and one species new to science. The phylogenetic relationships of all studied species and their relatives were examined based on the divergence of the COI mtDNA gene marker (barcoding). The conducted research clearly showed that the coastal part of the Black Sea and the adjacent pre-Caucasian river/land areas harbors a significant undescribed diversity, and that the transitional sea/river brackish biotopes are important reservoirs of the endemicity. A new genus, Litorogammarus gen. nov. is proposed for native pebble-dwelling species, namely Echinogammarus karadagiensis Grintsov, 2009, Echinogammarus mazestiensis Marin & Palatov, 2021 and the newly discovered Litorogammarus dursi sp. nov., from the lower (estuarine) part of the Durso River and adjacent coastal areas. These three species form a strongly supported molecular clade and share a number of characters such as smooth body without carinae and setae, antenna II armed with dense curled setae, lacking calceoli, pereopods III-VII with sparse, short setation, epimeral plates armed with spines only, telson lobes longer than broad, gradually tapering, bearing only spines. Pectenogammarus oliviiformis (Greze, 1985) comb. nov. is also discovered in the area and is re-described herein. Although this is probably one of the most abundant and common coastal pebble-dwelling species along the northeastern coasts of the Black Sea, it was previously poorly described and thus overlooked by researchers.

The effectiveness of protective layer in reducing fretting wear of Alloy 690TT tubes/ 405 stainless steel plates

Fretting experiments of Alloy 690TT tubes against 405 stainless steel (405 SS) plates were carried out to evaluate the influence of temperature on fretting performance of Alloy 690TT tubes in air. The results indicated that an adhesive and smooth protective third body layer was generated on Alloy 690TT tubes above a certain temperature, between 150 ℃ and 200 ℃ for given conditions. The protective layer was a mixture of oxides and transferred 405 SS, which was directly associated with fretting conditions. Thus, a wear transition map of Alloy 690TT was established. Besides, the results of this work also revealed that the plastic deformation of 285 ℃ was slighter than that of 150 ℃.

Large-Time Behavior of a Rigid Body of Arbitrary Shape in a Viscous Fluid Under the Action of Prescribed Forces and Torques

Let $${\mathcal B}$$ be a sufficiently smooth rigid body (compact set of $${\mathbb R}^3$$ ) of arbitrary shape moving in an unbounded Navier–Stokes liquid under the action of prescribed external force, $$F $$ , and torque, $$M $$ . We show that if the data are suitably regular and small, and $$F $$ and $$M $$ vanish for large times in the $$L^2$$ -sense, there exists at least one global strong solution to the corresponding initial-boundary value problem. Moreover, this solution converges to zero as time approaches infinity. This type of results was known, so far, only when $${\mathcal B}$$ is a ball.

Columnar neurons support saccadic bar tracking in Drosophila.

Tracking visual objects while maintaining stable gaze is complicated by the different computational requirements for figure-ground discrimination, and the distinct behaviors that these computations coordinate. Drosophila melanogaster uses smooth optomotor head and body movements to stabilize gaze, and impulsive saccades to pursue elongated vertical bars. Directionally selective motion detectors T4 and T5 cells provide inputs to large-field neurons in the lobula plate, which control optomotor gaze stabilization behavior. Here, we hypothesized that an anatomically parallel pathway represented by T3 cells, which provide inputs to the lobula, drives bar tracking body saccades. We combined physiological and behavioral experiments to show that T3 neurons respond omnidirectionally to the same visual stimuli that elicit bar tracking saccades, silencing T3 reduced the frequency of tracking saccades, and optogenetic manipulation of T3 acted on the saccade rate in a push-pull manner. Manipulating T3 did not affect smooth optomotor responses to large-field motion. Our results show that parallel neural pathways coordinate smooth gaze stabilization and saccadic bar tracking behavior during flight.

Diexanthema hakuhomaruae sp. nov. (Copepoda: Siphonostomatoida: Nicothoidae) from the Hadal Zone in the Northwestern Pacific, with an 18S Molecular Phylogeny.

Diexanthema copepods are ectoparasites on deep-sea isopods. This genus currently contains six species, all reported from the North Atlantic. Our study describes a new species of Diexanthema found on isopods from 7184 to 7186m depth in the Kuril-Kamchatka Trench, northwestern Pacific. We observed the copepod's morphology, made camera-lucida drawings, and compared our species with congeners. We determined partial sequences for its 16S rRNA and 18S rRNA genes and constructed an 18S-based maximum-likelihood copepod tree to place it phylogenetically. We identified the host isopod species through morphology and cytochrome c oxidase subunit I (COI, cox1) and 18S sequences. We described the copepod as Diexanthema hakuhomaruae sp. nov. and identified its host as Eugerdella cf. kurabyssalis Golovan, 2015 (Desmosomatidae). This is the first Diexanthema copepod from the Pacific and also from hadal depths. Diexanthema hakuhomaruae most closely resembles D. bathydiaita Richie, 1975, parasitic on Nannoniscus sp. (Nannoniscidae) in the Atlantic, but differs from the latter in having a smooth body surface and leg 5 in the ventrolateral region of the urosome. In the 18S tree, D. hakuhomaruae was the sister group to the Rhizorhina clade, which is consistent with the morphology-based hypothesis that they are closely related.