Strings Of Beads Research Articles

Interactions of sphingomyelin with biologically crucial side chain-hydroxylated cholesterol derivatives.

Oxysterols are interesting molecules due to their dual nature, reflecting beneficial and harmful effects on the body. An issue that still needs to be solved is how slight modification of their structure owing to the location of the additional polar group in the molecules affects their biological activity. With this in mind, we selected three side chain-hydroxylated oxysterols namely: 20(S)-hydroxycholesterol (20(S)-OH), 24(S)-hydroxycholesterol (24(S)-OH), and 27-hydroxycholesterol (27-OH), and examined their behavior in mixtures with the bioactive sphingolipid - sphingomyelin (SM). Our research was based on the Langmuir monolayer technique supplemented with molecular dynamics (MD) and microscopic observation of the films texture (Brewster angle microscopy, BAM, and atomic force microscopy, AFM). Additionally, since 20(S)-hydroxycholesterol has not been studied so far, we thoroughly characterized this oxysterol in one-component monolayers. Our studies showed differences in the interactions of the studied oxysterols and sphingomyelin. Namely, it was found that 20(S)-OH binds to SM, unlike 24(S)-OH and 27-OH, which both weakly interact with SM. This distinct behavior was interpreted within the molecular dynamics as being due to weak intermolecular interactions between 20(S)-OH molecules, which allowed easy incorporation of SM into the 20(S)-OH monolayer. In contrast, the strong oxysterol-oxysterol interactions occurring in monolayers with 24(S)-OH or 27-OH make this process more difficult. This may be important in the process of bone formation/resorption. Other aspects derived from our study are: (i) the tendency of oxysterols to incorporate into lipid rafts (leading to their modification in structure and function), as well as (ii) the formation of multilayer structures, in which oxysterols are arranged in the characteristic forms of "strings of beads", which may facilitate their transport across the membrane.

De grafheuvel van de bronstijdkrijger van Drouwen: onderzoeksgeschiedenis, hergebruik in de Vroege Middeleeuwen en regionale funeraire context

In 1927, A.E. van Giffen excavated a largely levelled burial mound near the village of Drouwen in the Dutch province of Drenthe. A few years later, Van Giffen published a summary report on the excavation, in which he concentrated on the lavish inventory of the central Sögel warrior burial. In 1985-1989, J.N. Lanting carried out further research at the site of the mound and revealed a large number of soil features from the Bronze Age and early Middle Ages. This second excavation has never been published before. The present article discusses both excavations. After an evaluation of all the excavation data the author zooms in on the warrior: what was his cultural context, and how can we interpret his social status in the region? The article concludes with an analysis of the spatial pattern of which this burial mound is a part. To do so, the author looks at all the prehistoric and protohistoric burial monuments in the area between the villages of Drouwen and Borger.Van Giffen’s profile drawings of the mound section he investigated suggest two construction phases. The oldest structure, a central mound of grey sand (c. 8 m across by c. 0.80 m high), was raised over the remains of a pyre. This first mound probably dates to the Early or early Middle Bronze Age. In the 16th century BC the warrior grave was dug into this mound; posts around the grave suggest the presence of a mortuary house or fence. The mound that was associated with this grave was c. 1.60 m high, possibly elongated (26 by 15 m or less) and surrounded by an oval ditch up to 1.6 m wide, with to the north a c. 3.40-m-wide opening. Whether there were any secondary burials is unknown.In the early Middle Ages, when the surrounding ditch had long since been filled in, the mound and its immediate vicinity became the location of a cemetery with graves arranged in rows (rijengrafveld). Only a small section of this cemetery was excavated (61 graves) so that the full period it was used is uncertain. Most graves were oriented east-west. Of the investigated graves, the majority were fully excavated, and several contained traces of a coffin. The buried individuals were mostly adults. Many did not produce any grave goods, and those items that were found were - in Van Giffen’s words - ‘armelijk’, rather poor. They are mostly iron knives and ‘prikkels’ (‘goads’, iron points, of unknown function, originally attached to a rod), bronze needle cases, keys, and one brooch. Of particular interest are three strings of beads and one isolated bead. To the extent they can be dated, all grave goods are comparatively late and could well be 8th and 9th-century, indicating that the cemetery ended at some point in the 9th century. The only human remains come from a small sub-recent pit close to Grave 29 (GrM-28439: 1244 ± 21 BP, i.e. 680-876 cal AD (2σ)).It is highly unlikely that the ‘Drouwen Warrior’ was anything more than a ‘big man’ whose network extended into northern Germany and possibly even Scandinavia. Whether he actually was a warrior in life is still an open question. When he was buried, at some point in the 16th century BC, several (very) ancient burial monuments already existed nearby. The mound of the warrior may have been part of an old linear alignment of these features. Why this particular mound was chosen in the early medieval period to situate a cemetery will probably always remain a mystery, although it is tempting to think that stories about the dead man buried there 2200 years earlier were still being told in the 7th or 8th century AD. That would tie in with the current archaeological narrative of the Bronze Age warrior as a person who strove after a heroic status after death, a form of immortality, created by the stories, passed on in each generation, of his martial, cosmopolitan and adventurous life.

A Restorable, Variable Stiffness Pneumatic Soft Gripper Based on Jamming of Strings of Beads

A Restorable, Variable Stiffness Pneumatic Soft Gripper Based on Jamming of Strings of Beads

VO Cluster-Stabilized H2O Adsorption on a TiO2 (110) Surface at Room Temperature.

We probe the adsorption of molecular H2O on a TiO2 (110)-(1 × 1) surface decorated with isolated VO clusters using ultrahigh-vacuum scanning tunneling microscopy (UHV-STM) and temperature-programmed desorption (TPD). Our STM images show that preadsorbed VO clusters on the TiO2 (110)-(1 × 1) surface induce the adsorption of H2O molecules at room temperature (RT). The adsorbed H2O molecules form strings of beads of H2O dimers bound to the 5-fold coordinated Ti atom (5c-Ti) rows and are anchored by VO. This RT adsorption is completely reversible and is unique to the VO-decorated TiO2 surface. TPD spectra reveal two new desorption states for VO stabilized H2O at 395 and 445 K, which is in sharp contrast to the desorption of water due to recombination of hydroxyl groups at 490 K from clean TiO2(110)-(1 × 1) surfaces. Density functional theory (DFT) calculations show that the binding energy of molecular H2O to the VO clusters on the TiO2 (110)-(1 × 1) surface is higher than binding to the bare surface by 0.42 eV, and the resulting H2O-VO-TiO2 (110) complex provides the anchor point for adsorption of the string of beads of H2O dimers.

"Orphan" Connexin43 in Plakophilin-2 Deficient Hearts Revealed by Volume Electron Microscopy.

Previous studies revealed an abundance of functional Connexin43 (Cx43) hemichannels consequent to loss of plakophilin-2 (PKP2) expression in adult murine hearts. The increased Cx43-mediated membrane permeability is likely responsible for excess entry of calcium into the cells, leading to an arrhythmogenic/cardiomyopathic phenotype. The latter has translational implications to the molecular mechanisms of inheritable arrhythmogenic right ventricular cardiomyopathy (ARVC). Despite functional evidence, visualization of these “orphan” (i.e., non-paired in a gap junction configuration) Cx43 hemichannels remains lacking. Immuno-electron microscopy (IEM) remains an extremely powerful tool to localize, with nanometric resolution, a protein within its native structural landscape. Yet, challenges for IEM are to preserve the antigenicity of the molecular target and to provide access for antibodies to reach their target, while maintaining the cellular/tissue ultrastructure. Fixation is important for maintaining cell structure, but strong fixation and vigorous dehydration (as it is routine for EM) can alter protein structure, thus impairing antigen-antibody binding. Here, we implemented a method to combine pre-embedding immunolabeling (pre-embedding) with serial block-face scanning electron microscopy (SBF-SEM). We utilized a murine model of cardiomyocyte-specific, Tamoxifen (TAM) activated knockout of PKP2. Adult hearts were harvested 14 days post-TAM, at this time hearts present a phenotype of concealed ARVC (i.e., an arrhythmogenic phenotype but no overt structural disease). Thick (200 µm) vibratome slices were immunolabelled for Cx43 and treated with nanogold or FluoroNanogold, coupled with a silver enhancement. Left or right ventricular free walls were dissected and three-dimensional (3D) localization of Cx43 in cardiac muscle was performed using SBF-SEM. Reconstructed images allowed us to visualize the entire length of gap junction plaques, seen as two parallel, closely packed strings of Cx43-immunoreactive beads at the intercalated disc. In contrast, in PKP2-deficient hearts we observed bulging of the intercellular space, and entire areas where only one of the two strings could be observed, indicating the presence of orphan Cx43. We conclude that pre-embedding and SBF-SEM allowed visualization of cardiac Cx43 plaques in their native environment, providing for the first time a visual complement of functional data indicating the presence of orphan Cx43 hemichannels resulting from loss of desmosomal integrity in the heart.

Meiosis Remodeled: Inclusion of New Parts to Poppit Bead Models Enhances Understanding of Meiosis

A long-standing tradition uses strings of poppit beads of different colors to model meiosis, especially to show how segments of paired homologous chromosomes are recombined. Our use of orthodontic latex bands to model cohesion of sister chromatids, and plastic coffee stirrers as microtubules, extends what can normally be achieved with &lsquo;standard&rsquo; commercial kits of beads, so emphasizing the importance of four key elements of meiosis: (a) the role of chromosome replication before meiosis itself begins; (b) pairing and exchange (chiasma formation) of homologous chromosomes during meiosis I; (c) centromere (kinetochore) attachment and orientation within/on the spindle during meiosis I and meiosis II; and (d) the differential loss of arm and centromere cohesion at onset of anaphase I and anaphase II. These are essential elements of meiosis that students best need to visualize, not just read and think about. Bead modeling leads them in that direction, as our gallery of figures and accompanying text show. <em>Primary image:&nbsp;</em>Unassembled components of &lsquo;PoppitMeiosis&rsquo; &ndash; a poppit bead exercise aimed at student learning of meiosis. Beads are snapped together to model bivalent chromosomes (on the right side), with double-stick tape (top) representing the synaptonemal complex, orthodontic latex bands representing cohesion rings, and coffee stirrers representing microtubule bundles that connect centromeres to the spindle poles.

Of Beads and Burials: A Microwear and Experimental Study of Early Medieval Glass and Amber Beads from the Merovingian Site of Lent-Lentseveld

Across Europe, hundreds of thousands of beads have been found in graves dating to the early medieval Merovingian period of 400-750 AD. Whilst recent studies have used microwear analysis to investigate amber beads, there are no known experimental microwear studies examining glass beads. This study proposes a methodological approach using experimental archaeology to explore the limits of microwear analysis for glass beads. This study examines two strings of beads from Lent-Lentseveld in the Netherlands. As the first experimental programme focused on the replica of use-wear on glass beads, this study includes different setups to test for use-wear development in different conditions. Experiments include a tumbling, string, and handling experiment, as well as the examination of Iron-Age re-enactment beads. Microwear analysis is conducted on 116 beads using a stereomicroscope, with magnifications of up to 160x. Analysis has shown that 100 or 150 hours is not enough for certain traces to develop on the experimental beads, with clear traces forming only from the string experiment. By comparing known traces from the experimental beads with the re-enactment beads and then with the archaeological beads, this study provides a framework for examining microwear traces on archaeological beads, particularly glass. This thesis presents the hypothesised biographies of these beads, with some beads displaying traces indicating higher degrees of wear and other beads displaying low to minimal traces of wear. Some beads are also interpreted as being acquired for the individual, whilst other beads are interpreted as having been heirlooms.

Role of sulfur in catalyzing fluorine atom fast etching of silicon with smooth surface morphology

Chemical reaction probabilities, defined as the number of silicon atoms removed per incident fluorine atom, have been investigated in mixtures of NF3 and SF6 plasmas in an inductively-coupled plasma reactor. Fluorine atom densities were measured by optical emission actinometry, and isotropic etching rates were measured by the degree of undercutting of SiO2-masked silicon by cross-sectional scanning electron microscopy. In addition, atomic force microscopy was used to examine surface morphology of etched Si surfaces. The F atom reaction probabilities derived from isotropic etching rates indicate an ∼30-fold higher reaction probability in SF6 plasmas compared with values in NF3 plasmas. Surfaces etched in SF6 plasmas were much smoother than those etched in NF3 plasmas. The addition of only 10% SF6 to an NF3 plasma produced a much higher reaction probability (∼5-fold) than in a pure NF3 plasma. This surprising enhancement of reaction probabilities for F with Si in SF6 plasmas is further investigated, based on the mechanism of adsorbed sulfur acting as a catalyst to greatly enhance the etching rate of Si. Dilute sulfur solutions in isopropyl alcohol were allowed to evaporate on the masked Si samples, depositing sulfur in relatively high concentrations near mask edges in ∼2 μm diameter periodic “strings of beads.” The sulfur-dosed sample etched several times faster at the center of each bead than a sample not exposed to sulfur that was placed side by side. The catalytic effect of sulfur is ascribed to an enhanced F sticking coefficient and/or decreased desorption rate on a surface covered with sulfur.

Magia ascunsă a unor amulete din Dacia preromană. În legătură cu un pandantiv-căldărușă din sudul Transilvaniei / The hidden magic of some amulets from pre-Roman Dacia. About a bucket-shaped pendant discovered in southern Transylvania

A bucket-shaped pendant was recently discovered by treasure hunters in southern Transylvania, in the Dacian fortresse from Tilişca probably. More than two decades ago, it was noted that among the pendants from pre-Roman Dacia was a category of finds made of bronze or iron which resemble the shape of a miniature bucket. #ese pendants were worn around the neck on strings, sometimes in combination with other items, for example glass beads. Chronologically, such pendants were used in the Dacian environment from the 1st century BC, but they are more numerous in contexts dated to the 1st century AD. Similar ornaments were also used in the following centuries in different cultural areas, for example in the territory of the Przeworsk culture, among the communities belonging to the Carpic culture or in the Sarmatian environment. It can be therefore presumed that the use of the pendants in question had a “supra-regional” character. In pre-Roman Dacia, they are mostly encountered in the areas outside the Carpathians range, mainly in Dacian settlements on the Siret valley, whereas similar finds are quite scarce in Transylvania. More recently, the number of finds has increased due to several archaeological investigations. Some examples are provided by the investigations carried out in the garden of the medieval castle at Hunedoara, in south-western Transylvania, which unearthed a cult place used since the Early Iron Age for various ritual practices, including votive offerings and human cremations and inhumations. Regarding the function of these pendants, Pliny the Elder lists numerous medical or protective remedies based on mineral, vegetal or animal substances. In order to be efficient, these had to get in close contact with the “patient”, so different means were used to keep them attached to the body. #ese included different types of containers which could have been made of organic materials, for example leather or textiles, while others were made of more durable materials, for example metal. One of the better known examples is the bulla, which was used in the Etruscan and Roman environment. #e bucket-shaped pendants more likely had fulfilled a similar role, holding medical and protective remedies of organic origin. Since they were lacking a lid, their contents could have been replaced according to the necessities. #eir presumed apotropaic function is also supported by their association with strings of glass beads and other metal pieces. Aside from these pendants, some bracelets having a split middle or a small middle tube have been identified in pre-Roman Dacia, but also in other cultural areas. #e small tubes were more likely used in the same way as the bucket-shaped pendants mentioned above. Various materials of mineral, vegetal, or animal origin could have been inserted to protect the owners of the respective bracelets (see Pliny the Elder, Nat. Hist. XXVIII. 9 and 47). Both the pendants and the bracelets were worn in a very visible manner, though their content, which aimed to offer protection, remained concealed. In both cases, the magical power of these remedies was augmented by the act of concealing them. Lastly, the widespread circulation of the bucket-shaped pendants was a result of individual mobility across the Dacian cultural area and also in the surrounding regions. #is mobility allowed the circulation across time and space of knowledge and practices that seldom left behind archaeological traces.

Stele și mărgele

The story behind these clothing accessories represented in the Prehistoric Art and in the stars makes that the man to be closer to sky (heaven, deity), the microcosmic Earth merging with the macrocosmic Universe. From the cycle of the clothing’s constellation symbolism we will approach the „Collier-Necklace” constellations. The "necklace (collier)" is meaningful myth-ritualistic clothing accessory and is represented on the sky by cluster of seven (nine) star forming the Pleiades in the constellation Taurus. Denomination of the "Necklace-Collier" is given in Romanian cosmogony for the Lira and Dolphin constellations. Necklace (collar, choker, lei, band, beads) has a rich sacred and ritualistic symbolism, being a sign of belonging to a certain age and social status, symbol of sentimental, or of gratitude and reward civil, or military, sealing the connection between the giver and the receiver. Moreover, it means the order (strings of beads), the respecting of customs, being an element of pomp and display of wealth, some worn daily, others within the sacred ritual ceremonies. Archaeologically, there were identified several statues bearing the "necklace" as "Adonis" from Ruginoasa and the idol of Truşeşti.

Saaremaa sariküllid: kihelkondlikud eripärad ja ajaloolised kandmisviisid / The Saaremaa sariküll: their regional characteristics and the ways they were worn historically

Saaremaa folk costumes are rich in different types of headgear. Women wore scarves, bonnets, woollen caps of various shapes, and, in later periods, hoof-shaped caps (kabimüts). Üll was the term used in Saaremaa for all sheepskin winter caps. These could come in different shapes; the most distinctive of these, however, was the horned women’s üll – sariküll. This black lambskin cap, with its long characteristic horns that give the cap its name, and its red or blue baize crown, has been a significant part of Saaremaa folk costumes.&#x0D; The earliest printed records of sarikülls worn in Saaremaa can be found in August Wilhelm Hupel’s Topographische Nachrichten von Lief- und Ehstland printed in Riga in 1782. Descriptions of sarikülls accompanied by drawings and photos were subsequently presented by Friedrich Carl Hermann Kruse in his Necrolivonica, as well as by Axel Olai Heikel in Die Volkstrachten in den Ostseeprovinzen und in Setukesien and by Ilmari Manninen in his history of Estonian folk costumes.&#x0D; The sariküll was a winter cap worn by both maidens and married women with two horns, which could be long or short, straight or bent. In the 19th century, sarikülls were worn in all of the parishes of Saaremaa as Sunday headgear. The caps were worn to church, but also used in weddings as a bridal headdress. Mourning ülls were also common. Records from Karja, Valjala, and Kihelkonna show that maidens were given a sariküll for confirmation. Sarikülls were not worn by children. All Saaremaa sarikülls preserved in museums today were worn with the horns at the front and back. There are some written records that suggest that horns were worn at the side in some parishes, but these records are not confirmed by the museum items. A scarf was worn on top of the üll.&#x0D; Similar caps were not worn in other regions of Estonia, but they can be found in the Slavic tradition. We can only speculate about how these striking horned caps found their way into the headgear of the Saaremaa women. Submission to Imperial Russian rule and the appearance of distant traders at fairs in Kuressaare may have brought the fashion of horned headgear to Saaremaa.&#x0D; To provide a typology of the sarikülls, I classified the caps by the shape, size, and the location of the horns, as well as the materials used for crafting the sariküll and the ways they were worn. I employed a qualitative approach, measuring and inspecting the sarikülls while studying the crafting techniques. To check how the pattern matched the original, I sewed one üll of each type. Sarikülls found at the Saaremaa Museum were used as models. In the course of gathering materials for my research, I studied sarikülls preserved at different museums: 6 caps from the Saaremaa Museum and 31 from the Estonian National Museum. Using materials found on their websites, I also studied two Saaremaa sarikülls now held by the Hungarian Ethnographic Museum and the National Museum of Finland.&#x0D; All the sarikülls I studied were hand-sewn following a pattern, but the materials used for different types of caps vary. The crown of the sariküll is sewn from either red or blue baize, using blue, black or red piping between the stitches. In some cases, the crown is also decorated with woollen threads and strings of glass beads. The linings of all sarikülls are made from white sheepskin. Variations in design are at their greatest in the horns giving the sariküll its name, and in the straight trimming, puhk, which connects the horns. A variety of materials were used for the horns and the puhk. Mustjala sarikülls are made from black and Eastern Saaremaa caps from grey lambskin. Kihelkonna ülls were made from black baize and Sõrve caps from black woollen fabric.&#x0D; The article contains drawings of all üll patterns; a table providing data on all the studied caps is found at the end of the article.&#x0D; Keywords: folk costumes, folk art, caps, Saare County, handicraft, sewing, leather

Hydrocarbon discovery in the Ordovician dolomite reservoirs in the Maigaiti slope, Southwest Depression of the Tarim Basin, and its exploration implications

A high-yield gas flow is produced from the dolomite reservoirs of the Ordovician Penglaiba Fm in Well Luosi 2 in the Southwest Depression of the Tarim Basin, recording as the most important major oil and gas discovery in the Maigaiti slope in recent 20 years. In this paper, the success and failure of wells drilled into the Ordovician during the exploration in the Maigaiti slope and its periphery were analyzed to clarify the future exploration targets in this area. Then, the distribution characteristics of Ordovician limestone weathered crust and internal dolomite reservoirs were investigated, the relationship between structural traps (e.g. formation and evolution) and hydrocarbon accumulation was analyzed, and the main factors controlling the Ordovician hydrocarbon accumulation in this area were defined. Finally, the relationship between hydrocarbon distribution and Neoproterozoic rift system was discussed. Accordingly, some findings were obtained. First, the Ordovician dolomite reservoirs are more developed than limestone reservoirs. Limestone weathered crust reservoirs of Middle Ordovician Yingshan Fm (upper member) are mainly distributed in fault zones, and their reservoir space is mainly composed of high-angle unfilled fractures. Internal dolomite reservoirs of Lower Ordovician Yingshan Fm (lower member) and Penglaiba Fm are laterally and stably distributed and their reservoir space is mainly composed of small dissolved pores which present “strings of beads” reflection characteristics on seismic profiles. Second, the Ordovician hydrocarbon is mainly discovered in the fault zones and the lithologic traps consisting of Ordovician karst dolomite reservoirs at periclines are the main exploration targets in subsequent operations. Third, the distribution of Cambrian source rocks is the key factor restricting the success rate of Ordovician oil and gas exploration. Under the control of Neoproterozoic rift system in the SW Tarim depression, the middle section of this depression is favorable for oil and gas exploration, and it includes multiple hydrocarbon source–reservoir–caprock assemblages, such as Ordovician–Upper Cambrian dolomites and Carboniferous mudstones, and Lower Cambrian dolomite and Middle Cambrian gypsum salt rocks.

Meroitic beadwork: an overview based on finds from Saï in ancient Nubia

The paper provides a preliminary overview of beads and pendants found on Saï Island at two Meroitic cemeteries, 8-B-5.A and 8-B-52.B. In the Meroitic period, strings of beads and pendants were an easily discerned motif in royal and private iconography, as well as in the arts and crafts, pottery included. The Saï bead and pendant assemblage is characterized by a variety of materials, techniques, and shapes that contribute significantly to a comparative study of Meroitic beadwork bead collections. Alongside objects already identified at other sites, richly imbued with visible Egyptian and Greek influences, the Saï assemblage contributes some new bead types. Moreover, the originally strung objects and their fragments confirm known bead patterns used over a long time between the 1st and 4th centuries AD, the date of the Saï necropolises. Finally, a comparison with other sites enables the tracing of some regional differences in Meroitic beadwork.

Zircon Growth during Progressive Recrystallization of Gabbro to Garnet Amphibolite, Eastern Segment, Sveconorwegian Orogen

The interpretation of whether a dated metamorphic zircon generation grew during the prograde, peak or retrograde stage of a metamorphic cycle is critical to geological interpretation. This study documents a case at Herrestad, in the eastern part of the 1±0 Ga Sveconorwegian Province, involving progressive metamorphic recrystallization of gabbro to garnet amphibolite and associated behaviour of Zr-bearing minerals. In this case, textures show that baddeleyite is by far the main source of Zr for metamorphic zircon growth. The amount of metamorphic zircon formed was primarily controlled by the degree of metamorphic recrystallization, which in turn was controlled by deformation and the presence of a fluid as a transport medium. Zircon in the Herrestad rocks shows a range of morphologies and internal textures at different degrees of metamorphic recrystallization. Igneous zircon occurs together with baddeleyite in coarse-grained olivine-free facies of the gabbro. Metamorphic polycrystalline zircon rims on baddeleyite and minute (<5 μm) bead-like zircon grains at Fe-Ti oxide boundaries characterize the transition to coronitic metagabbro. With increasing metamorphic recrystallization, polycrystalline zircon rims grow at the expense of baddeleyite and the amount of minute bead-like zircon increases, forming strings of zircon beads with increasing distance from Fe-Ti oxide grains. The progressive breakdown of baddeleyite results in polycrystalline zircon aggregates that become denser and finally form single grains in completely recrystallized garnet amphibolite. Late magmatic zircon crystallized at 156765 Ma, whereas metamorphic zircon dates amphibolite-facies metamorphic recrystallization at 97067 Ma. The Herrestad case illustrates a general rule that the bulk Zr budget in originally baddeleyite-bearing rocks will rapidly become locked into metamorphic zircon during the first event of metamorphic recrystallization, when silica and Zr are released from the igneous minerals. Incomplete metamorphic recrystallization and partial preservation of baddeleyite, however, also allows later stages of zircon formation. Thus, in incompletely reacted rocks the final result may be highly complex with microscale zircon of several age generations. (Less)

Optimisation of Weld Overlay Cladding Parameters Using Full-Factorial Design of Experiment

Weld Overlay Cladding (WOC) shares the same scientific principals as conventional welding where there are multiple governing factors that control the process and outcome. The present work employs a Design of Experiment (DoE) approach to optimising process parameters for cladding a nickel superalloy onto low alloy steel with the aim to improve productivity and quality. The arc current, the clad metal heating current were identified as the key process variables for this stage of experimentation. A full-factorial 4-by-2 test was carried out to identify the optimal levels. Results showed that there is a mild positive trend between the height of individual strings of beads and both variables. However no relationship was established with the depth of penetration, nor with the height of single or double layer stacks. The optimal level of the variables was therefore chosen to be the one that has the highest productivity rate as there were no significant differences. Further experimentation has been planned and described in this paper.

Morphology of mitochondrial nucleoids in respiratory-deficient yeast cells varies depending on the unit length of the mitochondrial DNA sequence.

We investigated the morphology of mitochondrial nucleoids (mt-nucleoids) and mitochondria in Saccharomyces cerevisiae rho(+) and rho(-) cells with DAPI staining and mitochondria-targeted GFP. Whereas the mt-nucleoids appeared as strings of beads in wild-type rho(+) cells at log phase, the mt-nucleoids in hypersuppressive rho(-) cells (HS40 rho(-) cells) appeared as distinct punctate structures. In order to elucidate whether the punctate mt-nucleoids are common to other rho(-) cells, we observed the mt-nucleoids in rho(-) strains that retain different unit lengths of the mitochondrial DNA (mtDNA) sequence. As a result, rho(-) cells that have long mtDNA sequences, of more than 30 kb, had mt-nucleoids with a strings-of-beads appearance in tubular mitochondria. In contrast, rho(-) cells that have short mtDNA sequences, of <1 kb, had punctate mt-nucleoids in tubular mitochondria. This indicates that the morphology of mt-nucleoids in rho(-) cells significantly varies depending on the unit length of their mtDNA sequence. Analyses of mt-nucleoids suggest that the punctate mt-nucleoids in HS40 rho(-) cells consist of concatemeric mtDNAs and oligomeric circular mtDNAs associated with Abf2p and other nucleoid proteins.

Simulated binding of transcription factors to active and inactive regions folds human chromosomes into loops, rosettes and topological domains.

Biophysicists are modeling conformations of interphase chromosomes, often basing the strengths of interactions between segments distant on the genetic map on contact frequencies determined experimentally. Here, instead, we develop a fitting-free, minimal model: bivalent or multivalent red and green ‘transcription factors’ bind to cognate sites in strings of beads (‘chromatin’) to form molecular bridges stabilizing loops. In the absence of additional explicit forces, molecular dynamic simulations reveal that bound factors spontaneously cluster—red with red, green with green, but rarely red with green—to give structures reminiscent of transcription factories. Binding of just two transcription factors (or proteins) to active and inactive regions of human chromosomes yields rosettes, topological domains and contact maps much like those seen experimentally. This emergent ‘bridging-induced attraction’ proves to be a robust, simple and generic force able to organize interphase chromosomes at all scales.

Branch merging on continuum trees with applications to regenerative tree growth

We introduce a family of branch merging operations on continuum trees and show that Ford CRTs are distributionally invariant. This operation is new even in the special case of the Brownian CRT, which we explore in more detail. The operations are based on spinal decompositions and a regenerativity preserving merging procedure of $(\alpha, \theta)$-strings of beads, that is, random intervals $[0, L_{\alpha, \theta}]$ equipped with a random discrete measure $dL^{-1}$ arising in the limit of ordered $(\alpha, \theta)$-Chinese restaurant processes as introduced recently by Pitman and Winkel. Indeed, we iterate the branch merging operation recursively and give an alternative approach to the leaf embedding problem on Ford CRTs related to $(\alpha, 2-\alpha)$-regenerative tree growth processes.

Renal artery fibromuscular dysplasia: in vivo optical coherence tomography insights

A 66-year-old woman with long-term essential hypertension presented with poorly controlled blood pressure in spite of six antihypertensive drugs. Percutaneous renal denervation was indicated as a treatment of resistant arterial hypertension. Renal angiography showed ‘strings of beads’ appearance characteristic of fibromuscular dysplasia (FMD) in the mid-segment of the right …

PÉROLAS DA LIBERDADE: JOALHERIA AFRO-BRASILEIRA

The text analyzes the jewelry that emerges from the context of the African diaspora in Brazil , dealing with creole jewelry disseminated primarily from Bahia in the eighteenth and nineteenth centuries , and strings of beads used in African-Brazilian religions , as well as its developments inside the Brazilian culture .