Half Turn Research Articles

Studying the rotational dynamics of a meter stick using the Arduino board and 3D printed parts

We present a low-cost experimental apparatus designed for studying the rotational dynamics of a meter stick. This apparatus uses everyday laboratory supplies, 3D printed parts, and an Arduino board for data acquisition. It consists of a common bearing fixed to a vertical axle, connected to the meter stick through a 3D printed spindle adapter. A thread attached to a hanging weight and winded around the spindle applies a constant external torque to the stick. The moment of inertia of the apparatus may be changed by incorporating weights into the apparatus through 3D printed adapters. An Arduino board records the time interval between consecutive half turns of the stick, allowing the calculation of the angular displacement over time. The data collected from experiments is compared with theoretical models. Among others, the effect of the applied torque, air resistance and moment of inertia of the stick is studied. This experimental apparatus is particularly suitable for undergraduate students enrolled in a classical mechanics course, offering them a practical, hand-on experience while remaining cost-effective.

Nudging visitors into pro-environmental behaviour: Assessing the use of a tidal information pillar for effective dynamic zoning

In the past few years, more human-wildlife conflicts have occurred as a result of increased human visitations, particularly in areas where space is scarce and functions need to co-exist. Nature organisations are increasingly challenged to improve nature protection on the one hand, while offering visitors high quality nature experiences on the other hand. To encourage both go hand in hand, nudging has recently received more attention. Nudging is a tool to subtly change human behaviour without imposing strict rules. It is, however, hardly applied in nature areas. Currently, experiments are taking place in the Dutch part of the Wadden Sea with alternating signage (nudging message based on real-time data of the area) aided by a tidal information pillar to encourage dynamic zoning. At low tide the signage indicates: freely accessible, at high tide the advice: ‘do not enter’. The purpose is to address visitors' sense of responsibility, nudge pro-environmental behaviour and reduce human-wildlife conflicts by limiting access. This article assesses the effectiveness of the alternating nudging signage, and especially the effectiveness of the signage ‘high tide – do not enter’. The results show that the signage on the pillar is most effective when visitors stop at the pillar and read the advice. Among these visitors, about half turn around. Among the visitors who do not encounter the signage and the pillar, the majority goes on to access the area. With this study, we aim to contribute to the knowledge on nudging as a tool to promote pro-environmental behaviour in nature areas.

Pathogenic residue insertion in neuronal nicotinic receptor alters intra- and inter-subunit interactions that tune channel gating

We describe molecular-level functional changes in the α4β2 nicotinic acetylcholine receptor (nAChR) by a leucine residue insertion in the M2 transmembrane domain of the α4 subunit associated with sleep-related hyperkinetic epilepsy. Measurements of agonist-elicited single channel currents reveal the primary effect is to stabilize the open channel state while the secondary effect is to promote reopening of the channel. These dual effects prolong the durations of bursts of channel openings equally for the two major stoichiometric forms of the receptor, (α4)2(β2)3 and (α4)3(β2)2, indicating the functional impact is independent of mutant copy number per receptor. Altering the location of the residue insertion within M2 shows that functionally pivotal structures are confined to a half turn of the M2 α-helix. Residue substitutions within M2 and surrounding α-helices reveal that both intra- and inter-subunit interactions mediate the increase in burst duration. These interactions impacting burst duration depend linearly on the size and hydrophobicity of the substituting residue. Together the results reveal a novel structural region of the α4β2 nAChR in which inter-helical interactions tune the stability of the open channel state.

Sect, Sectarian, Sectarianism: The Birth, Death, and Resurrection of an Analytical Category in the Study of Western Religions

Abstract This article charts the changing uses of the interconnected terms sect, sectarian, sectarianist, and sectarianism in the academic study of Judaism, Christianity, and Islam. Following a review of the term sect’s early roots in Greco-Roman antiquity and its distinctly Christian transformation, three main steps are analyzed in the genealogy of the category in modern scholarship: (1) deployments by Weber and his early followers; (2) an influential sociological turn in the latter half of the twentieth century; and (3) a sharp decline in the years around the turn of the century in the popularity of sect as a category, followed by a redefinition of its derivative terms (sectarian, etc.) in recent years. Toward the end of the article, lessons are drawn from this genealogy for the future use of the category within scholarship.

3D Finite Element Model of Human Ear with 3-Chamber Spiral Cochlea for Blast Wave Transmission from the Ear Canal to Cochlea

Blast-induced auditory trauma is a common injury in military service members and veterans that leads to hearing loss. While the inner ear response to blast exposure is difficult to characterize experimentally, computational models have advanced to predict blast wave transmission from the ear canal to the cochlea; however, published models have either straight or spiral cochlea with fluid-filled two chambers. In this paper, we report the recently developed 3D finite element (FE) model of the human ear mimicking the anatomical structure of the 3-chambered cochlea. The model consists of the ear canal, middle ear, and two and a half turns of the cochlea with three chambers separated by the Reissner's membrane (RM) and the basilar membrane (BM). The blast overpressure measured from human temporal bone experiments was applied at the ear canal entrance and the Fluent/Mechanical coupled fluid-structure interaction analysis was conducted in ANSYS software. The FE model-derived results include the pressure in the canal near the tympanic membrane (TM) and the intracochlear pressure at scala vestibuli, the TM displacement, and the stapes footplate (SFP) displacement, which were compared with experimentally measured data in human temporal bones. The validated model was used to predict the biomechanical response of the ear to blast overpressure: distributions of the maximum strain and stress within the TM, the BM displacement variation from the base to apex, and the energy flux or total energy entering the cochlea. The comparison of intracochlear pressure and BM displacement with those from the FE model of 2-chambered cochlea indicated that the 3-chamber cochlea model with the RM and scala media chamber improved our understanding of cochlea mechanics. This most comprehensive FE model of the human ear has shown its capability to predict the middle ear and cochlea responses to blast overpressure which will advance our understanding of auditory blast injury.

Nucleosome chaperone activity of LEDGF and HDGF2 characterized with single molecule force spectroscopy.

The nucleosome, two turns of DNA wrapped around a histone octamer, is the fundamental structure of DNA organization in eukaryotic cells. Lens epithelium-derived growth factor (LEDGF) and hepatoma-derived growth factor 2 (HDGF2) are recently discovered proteins that facilitate transcription without ATP hydrolysis, suggesting roles as nucleosome chaperones during the integration of lentiviral DNA, including HIV-1 DNA, into infected cell genomes. Both proteins have methyl-lysine reading PWWP domains that can recognize H3K36me2/3 marks. To better understand these activities, we used optical tweezers to stretch reconstituted DNA nucleosome arrays containing twelve Widom 601 positioning sequences with unmodified (WT) and methylated histones (mimicking the H3K36me2/3 modifications), in the presence of LEDGF and HDGF2. To test the function of these nucleosome chaperone proteins during HIV-1 DNA integration, we exposed the modified nucleosomes to HIV-1 integrase (IN) together with equal concentrations of LEDGF and HDGF2. Analysis of force-extension data showed that while some destabilization of the inner wrapping of nucleosomes occurs due to histone methylation, exposure to chaperones results in further destabilization. Notably, the outer half turn unwrapping of nucleosomes that typically occurs at lower forces disappears with chaperone binding. Kinetic analysis of histone-DNA interactions in the presence of these chaperones via survival probability and confocal fluorescence measurements indicates that LEDGF not only facilitates nucleosome unwrapping but also moderately promotes nucleosome reassembly. These results offer insight into the functions of LEDGF and HDGF2 as nucleosome chaperone proteins and their effect on IN binding to the nucleosome array.

Method to estimate the basal turn length in inner ear malformation types

The mathematical equations to estimate cochlear duct length (CDL) using cochlear parameters such as basal turn diameter (A-value) and width (B-value) are currently applied for cochleae with two and a half turns of normal development. Most of the inner ear malformation (IEM) types have either less than two and a half cochlear turns or have a cystic apex, making the current available CDL equations unsuitable for cochleae with abnormal anatomies. Therefore, this study aimed to estimate the basal turn length (BTL) from the cochlear parameters of different anatomical types, including normal anatomy; enlarged vestibular aqueduct; incomplete partition types I, II, and III; and cochlear hypoplasia. The lateral wall was manually tracked for 360° of the angular depth, along with the A and B values in the oblique coronal view for all anatomical types. A strong positive linear correlation was observed between BTL and the A- (r2 = 0.74) and B-values (r2 = 0.84). The multiple linear regression model to predict the BTL from the A-and B-values resulted in the following equation (estimated BTL = [A × 1.04] + [B × 1.89] − 0.92). The manually measured and estimated BTL differed by 1.12%. The proposed equation could be beneficial in adequately selecting an electrode that covers the basal turn in deformed cochleae.

The human pre-replication complex is an open complex

In eukaryotes, DNA replication initiation requires assembly and activation of the minichromosome maintenance (MCM) 2-7 double hexamer (DH) to melt origin DNA strands. However, the mechanism for this initial melting is unknown. Here, we report a 2.59-Å cryo-electron microscopy structure of the human MCM-DH (hMCM-DH), also known as the pre-replication complex. In this structure, the hMCM-DH with a constricted central channel untwists and stretches the DNA strands such that almost a half turn of the bound duplex DNA is distorted with 1 base pair completely separated, generating an initial open structure (IOS) at the hexamer junction. Disturbing the IOS inhibits DH formation and replication initiation. Mapping of hMCM-DH footprints indicates that IOSs are distributed across the genome in large clusters aligning well with initiation zones designed for stochastic origin firing. This work unravels an intrinsic mechanism that couples DH formation with initial DNA melting to license replication initiation in human cells.

A Geometry Optimization of Spiral Grain Selector During Directional Solidification of Nickel‐Based Superalloy

A spiral grain selector with excellent geometric parameters can ensure qualified single-crystal (SX) is selected while decreasing lesser thermal gradient (G) during casting of SX nickel-based superalloy . In this paper, three configurations of spiral grain selectors with different height of starter block (H = 18, 25, 35 mm) and same spiral passage are adopted. Based on the quantitative analysis of orientation distribution of grains in starter block, it is found that the deviation of <001> oriented grains in the projection zone of spiral passage inlet (circle with a diameter of 4 mm) are smaller than grains of overall cross-section (circle with a diameter of 10 mm), which verify that starter block with smaller diameter have better optimization effect of grain orientation. Moreover, the average deviation of <001> oriented grains decreases to a range of 6.6–10.8° when the height of starter block is 18–27 mm, and SX selection is completed on the position of less than half turn in spiral passage regardless of the number of grains in the inlet position. Finally, a modified spiral grain selector is designed from the perspective of practical production, of which total height is reduced by at least 15 mm, and can decrease lesser G at some extent during casting .

Analysis and mitigation of the bending deformation in girth-welded slender pipes with numerical modelling and experimental measurement

Girth welded pipes are extensively used in the components of energy and chemical industries. The welding deformation modes depend on various influential factors, such as process schemes and geometric dimensions. The objective of this study is to investigate the characteristics and mechanism of the bending deformation generated in the girth welded slender pipes, and to develop mitigation schemes. Firstly, several 304-type stainless steel pipes were girth welded using four different welding schemes, and the 3D shape measuring system was employed to capture the basic welding deformation modes. Numerical models were developed to simulate the corresponding welding processes with experimental verification. And the mechanism of bending deformation was further clarified based on inherent strain theory. The results show that obvious bending was observed in the pipe of continuous full turn welding due to the non-uniform distribution of the axial residual plastic strain on the circumference. Welding of half turn tends to generate a bending from the weld starting position to the finish position besides the bending toward the weld side, which brings about the mutual elimination of the bending deformation with same direction half-turns and the superposition with reverse direction half-turns. Furthermore, a dual-torch scheme was proposed for girth welding of slender pipes and presented a great potential to mitigate the bending deformation with an improved welding efficiency.

2D DNA lattices assembled from DX-coupled tiles

HypothesisFormation of coupled double crossovers (DXs) in a circular 106-mer oligonucleotide (c106nt) could generate stable tiles with the tile core span of 10 half turns. The large-span tiles with complicated curvatures and mechanics could assemble 2D lattices under different environments. Hence, 2D DNA lattice structures based on tile types and sequences, tile packing modes of corrugation and non-corrugation, and assembly media of solution and the substrate-solution interface are yet to be explored. ExperimentsTwo c106nt scaffold strands with different sequences were synthesized. Four types of tiles, two rectilinear and two triangular tiles, were designed and their 2D assemblies were examined by atomic force microscopy (AFM). FindingsThe DX-coupled tiles provided fair strength and rigidity to assemble 2D lattices. Due to the complicated curvature and mechanics of tiles, the two-tile assemblies in solution displayed a few ripe lattices of ribbons, tubes, or polycrystalline aggregates as the minor products and tile oligomers as the major products; whereas the one-tile assemblies via substrate mediation exhibited well-organized monolayer lattices covering the whole mica disk. The herringbone packing patterns were first observed in DNA nanostructures. Based on the lattice constants and the surface coverages of lattices, we estimated the lattice yields for the substrate-mediated assemblies.

Three-Dimensional Finite Element Modeling of Blast Wave Transmission From the External Ear to a Spiral Cochlea.

Blast-induced injuries affect the health of veterans, in which the auditory system is often damaged, and blast-induced auditory damage to the cochlea is difficult to quantify. A recent study modeled blast overpressure (BOP) transmission throughout the ear utilizing a straight, two-chambered cochlea, but the spiral cochlea's response to blast exposure has yet to be investigated. In this study, we utilized a human ear finite element (FE) model with a spiraled, two-chambered cochlea to simulate the response of the anatomical structural cochlea to BOP exposure. The FE model included an ear canal, middle ear, and two and half turns of two-chambered cochlea and simulated a BOP from the ear canal entrance to the spiral cochlea in a transient analysis utilizing fluid-structure interfaces. The model's middle ear was validated with experimental pressure measurements from the outer and middle ear of human temporal bones. The results showed high stapes footplate (SFP) displacements up to 28.5 μm resulting in high intracochlear pressures and basilar membrane (BM) displacements up to 43.2 μm from a BOP input of 30.7 kPa. The cochlea's spiral shape caused asymmetric pressure distributions as high as 4 kPa across the cochlea's width and higher BM transverse motion than that observed in a similar straight cochlea model. The developed spiral cochlea model provides an advancement from the straight cochlea model to increase the understanding of cochlear mechanics during blast and progresses toward a model able to predict potential hearing loss after blast.

Symptom: Unilateral Hearing Loss

Symptom: Unilateral Hearing Loss

Morpho-molecular description of a new HAB species, Pseudocochlodinium profundisulcus gen. et sp. nov., and its LSU rRNA gene based genetic diversity and geographical distribution

Harmful algal blooms (HABs) caused by an unknown dinoflagellate species have frequently occurred in the Pearl River Estuary, China Since 2006. These blooms were associated with severe water discoloration and economic losses, ranging from several km2 to 300 km2 with the maximum recorded cell density being 2.77 × 107 cells⋅L−1. This unknown dinoflagellate species was initially identified as Cochlodinium geminatum and subsequently reclassified as Polykrikos geminatus. However, after reviewing the original descriptions for Cochlodinium geminatum sensu Schütt (1895) and the genus Polykrikos, we considered this species is incongruent with their original descriptions. Further morphological examinations and particularly phylogenetic analyses based on the SSU and partial LSU rRNA genes of isolates and resting cysts from China and Japan prompted us to consider it a new species of a new genus. This new species was proposed to be Pseudocochlodinium profundisulcus gen. et sp. nov., based on its open comma-shaped apical structure complex (ASC), cingulum encircling the cell less than one and a half turns, a deep sulcus with a torsion of a half turn, either single cell or cell chain consisting of two cells with the same number of nuclei and zooids, the resting cyst bearing lobed ornaments, and the evolutionary distances from Polykrikos (and others) on the phylogenetic trees constructed using the concatenated SSU and partial LSU rRNA gene sequences. Metabarcoding investigation of surface sediment samples collected in China revealed that the species to be widely present along the entire Chinese coast with the highest abundance in the South China Sea. Further re-analysis of the Tara Oceans metabarcoding dataset targeting the SSU rRNA gene V9 domain suggested a global distribution of this new genus. Phylogenetic analyses on 46 OTUs (average length: ∼552 bases) of its LSU rRNA gene sequences (mainly D1-D2 domains) obtained from surface sediment samples revealed intraspecific genetic diversity of this species. Interestingly, based on the different distributions and the abundance of these OTUs along the coast of China, this species appeared to have expanded its distribution from the South China Sea to the northern Yellow Sea, or preferred a warm water habitat. We consider that the present work improves the taxonomy and provides important insights into the biogeography of Pseudocochlodinium profundisulcus.⋅

Surgeries of the Gieseking hyperbolic ideal simplex manifold

In our Novi Sad conference paper (1999) we described Dehn type surgeries of the famous Gieseking (1912) hyperbolic ideal simplex manifold $\mathcal{S}$, leading to compact fundamental domain $\mathcal{S}(k)$, $k = 2, 3, \dots$ with singularity geodesics of rotation order $k$, but as later turned out with cone angle $2(k-1)/k$. We computed also the volume of $S(k)$, tending to zero if $k$ goes to infinity. That time we naively thought that we obtained orbifolds with the above surprising property. As the reviewer of Math. Rev., Kevin P. Scannell (MR1770996 (2001g:57030)) rightly remarked, is in conflict with the well-known theorem of D. A. Kazhdan and G. A. Margulis (1968) and with the work of Thurston, describing the geometric convergence of orbifolds under large Dehn fillings. In this paper we refresh our previous publication. Correctly, we obtained cone manifolds (for $k > 2$), as A. D. Mednykh and V. S. Petrov (2006) kindly pointed out. We complete our discussion and derive the above cone manifold series (Gies.1 and Gies.2) in two geometrically equivalent form, by the half turn symmetry of any ideal simplex. Moreover we obtain a second orbifold series (Gies.3 and 4), tending to the regular ideal simplex as the original Gieseking manifold.

Structural adaption of the nasal conchae of Eurasian common moorhen (Gallinula chloropus chloropus, Linnaeus, 1758)-Histomorphological study.

In the current study, the nasal conchae of the Eurasian common moorhen were grossly and histologically examined for 20 healthy adult birds. Rostral (RC), middle (MC), and caudal (CC) conchae in each side of the nasal cavity were observed. The anatomical cross sections revealed that, the RC was noncurved in its rostral and middle parts, and one half turn in its caudal part. The MC was one half turn in its rostral part, one turn in its middle part, and one and one half turns in its caudal part. The CC was like a pouch from the lateral wall of the nasal cavity. Histologically, the distribution of the mucous glands was different among the three conchae; In RC, the ducts of these glands were intraepithelial, while the acini were located in the propria-submucosa toward the convex surface of the concha and absent toward its concave surface. In MC, they were intraepithelial and opened directly on the surface epithelium of the convex and concave surfaces. In CC, they were intraepithelial in few number near the convex surface of the concha and with abundant number in the propria-submucosa and absent near the concave surface. The RC was richer in the vascularity than the other two conchae. The nasal conchae were functioning for conditioning of the inspired air and entrapping the antigens presented in it.

A rare case report of ovarian torsion in first trimester at tertiary care centre

Torsion of the ovary is the total or partial rotation of the adnexa around its vascular axis or pedicle. Although the exact Etiology is unknown, common predisposing factors include moderate size cyst, free mobility and long pedicle. Torsion of ovarian tumours occurred predominantly in the reproductive age group. The majority of the cases presented in pregnant (22.7%) than in non-pregnant (6.1%) women 3. Here we present a case report of an ovarian torsion in 1st trimester of pregnancy. Who conceived after infertility treatment, patient underwent exploratory laparotomy using a pfannensteil incision, Right ovarian pedicle torsion present two and a half turns, released. Right oophorectomy done. Post-operatively patient continued the pregnancy. Ovarian torsion is an urgent gynaecological surgery and can occur during pregnancy. Diagnosis can usually be made on the basis of the characteristic clinical presentation in conjunction with ultrasound evidence of a unilaterally enlarged adnexal mass. Treatment options are limited to surgery, either by laparoscopy or laparotomy should be considered in the development of the adnexal torsion regardless of the gestational age.

Exploring Motifs In Towe Songke, Manggaraian Ethnic Woven Fabric, In Mathematics Perspective

Connection between mathematical content and the cultures of learnersin mathematics education should be acknowledged and explored. Thisresearch, conducted using a qualitative research approach, withethnographic methods, explored the relationship between formalmathematics especially geometric patterns and Motifs of ManggaraiEthnic Woven Fabric, known as Towe Songke in Cibal, ManggaraiRegency, a rural area in East Nusa Tenggara Indonesia. Total 3weavers of the age ranging from 20 to 40 selected based on theirweaving knowledge and communication skills. Data were obtainedthrough interviews, observations, field notes, and documentations.The research resulted in how mathematics learning on subjects such as geometry and geometry transformation was associated with the local cultural context of Manggarai. This study identified the line symmetry and the effect of geometric transformations (translations,reflections, rotation, and reflection) of several motifs in Towe Songke. Most of motifs which are found in Towe Songke forms Frieze Pattern F7 because these motifs can be seen as translation, horizontal reflection, vertical reflection and half turn rotation symmetry.

How Is Helicity (and Twist) Partitioned in Magnetohydrodynamic Simulations of Reconnecting Magnetic Flux Tubes?

Abstract Magnetic helicity conservation provides a convenient way to analyze specific properties (namely, the linkage and twist) of reconnecting flux tubes and yield additional insight into the pre- and post-reconnection states of magnetic structures in the solar atmosphere. A previous study considered two flux tubes with footpoints anchored in two parallel planes. They showed that reconnection would add self-helicity equivalent to a half turn of twist to each flux tube. We address a related and fundamental question here: if two flux tubes anchored in a single plane reconnect, what are the resulting twists imparted to each of the reconnected tubes? Are they equal and do they have a simple exact value independent of footpoint location? To do this, we employ a new (computationally efficient) method which subdivides each flux tube into distinct elements and calculates the mutual helicity of many elemental pairs, the sum of which determines the self-helicity of the overall flux tube. Having tested the method using a simple analytical model, we apply the technique to a magnetohydrodynamic simulation where initially untwisted magnetic flux tubes are sheared and allowed to reconnect (based on a previous reconnection model). We recover values of self-helicity and twist in the final end state of the simulations which show excellent agreement with theoretical predictions.

Unmasking communism: Ayi Kwei Armah, black Marxism, and the cultural turn, 1967-1984

ABSTRACT Can the repudiation of Eurocentric Marxism and embrace of Afrocentrism in Ayi Kwei Armah’s essays explain his shift from writing realist to historical novels? Contextualizing Armah’s work in relation to the global cultural turn in the second half of the twentieth century, this article understands his critique of racial capitalism and program of re-Africanization as a black Marxism. It then explains Armah’s embrace of the form of the historical novel in Two Thousand Seasons via a reading of Fragments, which allegorizes a key political and aesthetic contradiction: the changes in culture and consciousness requisite for decolonization cannot occur within the established structures of representation. Reading Armah’s historical novels through the black Marxism of his essays indicates the horizons of his work for Marxist approaches to African literature today and remains important for understanding the legacy of revolutionary Fanonism.