Obtuse Angle Research Articles

Optimal design of a fractional order immittance in the second quadrant with wide CPZ

This paper presents a design technique to realize fractional order (FO) immittance in the second quadrant of the impedance plane, using Bruton’s generalized immittance converter (GIC). Design guidelines are developed based on a sub-optimal analysis of phase error resulted by non-ideal op amps. The analysis takes into account finite open-loop dc gain and finite unity-gain frequency of practical op amps and aim to maximize the constant phase zone for a given phase band specification. The fractance of the realized fractor can also be tuned to a desired value by varying one of the GIC resistances. Several simulations and experimental validations are demonstrated. Also, high Q, FO bandpass filter with wide tuning range is presented as an application of the designed obtuse angle fractor.

Icriodus riosi, NUEVA ESPECIE DE CONODONTO EN EL DEVÓNICO INFERIOR DEL PIRINEO CENTRAL ESPAÑOL

Se describe y discute el conodonto Icriodus riosi n. sp. del Devónico Inferior de los Pirineos Centrales Españoles. Esta especie se caracteriza por presentar un cuerpo principal con bordes rectos y un corto proceso posterior externo que forma un ángulo obtuso con el eje principal del elemento, estando ésta probablemente emparentada con las especies del grupo curvicauda-celtibericus. Su rango estratigráfico abarca desde la Zona pireneae (Praguiense tardío), ligeramente por debajo del comienzo de la Zona kitabicus, hasta la parte inferior de la Zona nothoperbonus (Emsiense inferior tardío). La abundante y diversificada asociación de diferentes especies del género en las mismas secciones, como por ejemplo Ic. curvicadua, Ic. celtibericus, Ic. bilatericrescens o Ic. gracilis, sugieren que durante este intervalo temporal se produjo un proceso de radiación evolutiva del grupo, fenómeno que hasta ahora sólo había sido documentado en el género Polygnathus.

Investigations on stainless steel T- and Y-joints in cold-rolled circular hollow sections

With the wide applications of stainless steel structures, stainless steel joints in cold-rolled tubes are increasingly used in building structures. However, the behaviors and the design methods of tubular joints were rarely studied. This study conducted experimental and numerical investigations on austenitic stainless steel T- and Y-joints in cold-rolled circular hollow sections with axial compression in brace. A total of six T-joints and three Y-joints were tested. The effects of the geometric configurations and the preload in the chord on the behaviors of the joint were considered. The material properties, failure modes, joint strengths and load-deformation curves were all reported. Test results showed that the failure mode of T-joints was the plastification failure of the chord on the chord face as well as the chord side wall. The failure mode of Y-joints was similar to that of T-joints while the deformation mainly occurred on the side of chord face with an obtuse angle to brace. Comparisons of the predictions using the CIDECT recommendations and the tests results indicated that the predictions were conservative. Finite element models were developed and validated using the test results. A total of 192 finite element models were analyzed to evaluate the effect of geometric properties and the chord preload on the joint strength. The functions of Qu and Qf in CIDECT for the chord plastification failure were modified based on the parametric analysis results. Comparisons of the predictions and the test results show that the proposed modified equations had a good accuracy.

Dyspnoea from a rapidly growing intrathoracic mass

A 54-year-old man presented with progressive dyspnoea and non-productive cough for 2 months. A physical examination revealed diminished breath sounds and dullness to percussion on the right side. A preoperative...

Experimental and Numerical Study on the Bubble Dynamics near Two-Connected Walls with An Obtuse Angle

This study is concerned with the dynamic characteristics of bubbles near two connected walls (one horizontal and the other inclined with an obtuse angle from the horizontal one). In this study, we set up an experiment system to conduct typical cases, and the boundary element method is employed to explain the bubble behavior and study the effect of relative parameters. Comparing the two mutually perpendicular walls, we find that the liquid jet deviates from the horizontal direction within a much shorter range. On the intersection of the two walls, the motions of bubbles have similar trends. The relatively low pressure between the bubble and walls causes the transition of the bubble, and a local high-pressure zone leads to the formation of a liquid jet. Moreover, there are moments when the two walls are evenly stressed in the first bubble cycle. Through parameter analysis, we find that the jet directions of bubbles perform interesting discrepancies for different buoyancy and distances to walls. Some instructive conclusions are given to serve practical applications.

Pore structure characterization and its effect on methane adsorption in shale kerogen

Pore structure characterization and its effect on methane adsorption on shale kerogen are crucial to understanding the fundamental mechanisms of gas storage, transport, and reserves evaluation. In this study, we use 3D scanning confocal microscopy, scanning electron microscopy (SEM), X-ray nano-computed tomography (nano-CT), and low-pressure N2 adsorption analysis to analyze the pore structures of the shale. Additionally, the adsorption behavior of methane on shales with different pore structures is investigated by molecular simulations. The results show that the SEM image of the shale sample obviously displays four different pore shapes, including slit pore, square pore, triangle pore, and circle pore. The average coordination number is 4.21 and the distribution of coordination numbers demonstrates that pores in the shale have high connectivity. Compared with the adsorption capacity of methane on triangle pores, the adsorption capacity on slit pore, square pore, and circle pore are reduced by 9.86%, 8.55%, and 6.12%, respectively. With increasing pressure, these acute wedges fill in a manner different from the right or obtuse angles in the other pores. This study offers a quantitative understanding of the effect of pore structure on methane adsorption in the shale and provides better insight into the evaluation of gas storage in geologic shale reservoirs.

Are anterior urethral valve and anterior urethral diverticulum two separate entities: A radiological and endoscopic review

Anterior urethral valve (AUV) and anterior urethral diverticulum (AUD) are two rare causes of anterior urethral obstruction with variable presentation and anatomy. Their existence as the same or different entity is still debatable, and management has not yet been standardized. This study is a retrospective review of cases diagnosed with anterior urethral obstruction and correlation of radiological and endoscopic anatomy of AUV and AUD. A retrospective review of cases diagnosed with AUV and AUD, between May 2013 and February 2020 is presented. The presentation, laboratory, radiological and endoscopic anatomy along with the management required was reviewed. A special emphasis has been given on the correlation of radiological and endoscopic anatomy and an attempt has been made to standardize the management. A total of 8 patients with age ranging from 2 months to 9 years were reviewed. Poor urinary stream and recurrent UTI was the commonest presentation. The anatomy of the anterior urethra on VCUG (voiding cystourethrogram) and Urethrocystoscopy was correlated. Two sets of patients were identified. In the first set, five cases on endoscopy had findings of the classical valve-like fold in the anterior urethra with immediate proximal dilation of the urethra giving the appearance of a 'pseudodiverticula' without any definite opening. In three of these cases, endoscopic findings correlated well with radiological findings of 'pseudodiverticula' in which dilated proximal urethra formed an obtuse angle with the ventral floor of the urethra. The other set of four patients had a 'true diverticula' on endoscopy with a well-defined mouth and prominent distal lip, correlating well with radiological findings of a 'true diverticula' forming an acute angle with the ventral floor of the urethra. One case on endoscopy had both an anterior urethral valve with a proximal 'pseudodiverticula and a large wide-mouthed bulbar 'true diverticula'. All the patients with classical valves were successfully treated using a resectoscope while two patients with 'true diverticula' were successfully managed by incising the distal lip. One of the patients previously managed for the posterior urethral valve (PUV) had both classical valves in the anterior urethra with proximal 'pseudodiverticula' and a bulbar 'true diverticula'. The AUV was ablated with a resectoscope while 'true diverticula' required diverticulectomy. All the patients after follow up of 3 months-8 years, were asymptomatic except the one with 'true diverticulum' who remained symptomatic after TUR (Trans-urethral resection) and required vesicostomy. AUV and AUD both can cause obstructive uropathy. The proximal dilatation related to AUV cannot be labeled as a 'true diverticula', which lacks a classical orifice. The distal obstructing lip of 'true diverticula' should not be confused with a classical mucosal valve-like fold seen in AUV. While AUV and small AUD can be treated with endoscopic ablation, large diverticula as a result of wide spongiosal defects require surgical excision. A good understanding of their radiological and endoscopic anatomy is required to differentiate them and decide for appropriate management. Based on our experience, AUV and AUD should be differentiated and should be considered as two separate entities.

Midface Morphology and Growth in Syndromic Craniosynostosis Patients Following Frontofacial Monobloc Distraction.

Facial advancement represents the essence of the surgical treatment of syndromic craniosynostosis. Frontofacial monobloc distraction is an effective surgical approach to correct midface retrusion although someone consider it very hazardous procedure. The authors evaluated a group of patients who underwent frontofacial monobloc distraction with the aim to identify the advancement results performed in immature skeletal regarding the midface morphologic characteristics and its effects on growth. Sixteen patients who underwent frontofacial monobloc distraction with pre- and postsurgical computed tomography (CT) scans were evaluated and compared to a control group of 9 nonsyndromic children with CT scans at 1-year intervals during craniofacial growth. Three-dimensional measurements and superimposition of the CT scans were used to evaluate midface morphologic features and longitudinal changes during the craniofacial growth and following the advancement. Presurgical growth was evaluated in 4 patients and postsurgical growth was evaluated in 9 patients. Syndromic maxillary width and length were reduced and the most obtuse facial angles showed a lack in forward projection of the central portion in these patients. Three-dimensional distances and images superimposition demonstrated the age did not influence the course of abnormal midface growth. The syndromic midface is hypoplastic and the sagittal deficiency is associated to axial facial concavity. The advancement performed in mixed dentition stages allowed the normalization of facial position comparable to nonsyndromic group. However, the procedure was not able to change the abnormal midface architecture and craniofacial growth.

Experimental study of natural heat transfer enhancement in a rectangular finned surface by EHD method

Extended surfaces are widely used in various industries as passive methods for enhancing heat transfer. The thermal boundary layer formed at the heat exchange surfaces is considered as a barrier to heat transfer from the surface and restrains their efficiency. As an active and inexpensive method of enhancing heat transfer, electrohydrodynamics (EHD) can be used to solve this problem and strengthen the heat transfer rate. In the present study, by combining the active and inactive methods of heat transfer enhancement, the effect of electrohydrodynamics on natural heat transfer is examined experimentally on a rectangular surface with vertical fin. The base plate of the fins is subjected to constant heat flux and the temperature of the plate is measured during the test period. The experiments were performed for different angles, including acute and obtuse angles, and by applying different voltages. Based on the obtained results, experimental equations for calculating the electrohydrodynamic Nusselt number at the finned surface are presented as a function of the applied voltage. Experimental results show that the electrostatic field has a significant effect on increasing the heat transfer from this extended surface. Finally, the formed corona wind vortexes between electrodes, caused by applying high voltage electrostatic field is detected.

In Situ Pulmonary Artery Thrombosis: Unrecognized Complication of Radiation Therapy.

OBJECTIVE. The purpose of this study is to evaluate the CT and clinical characteristics of in situ pulmonary artery thrombosis (PAT) associated with radiation therapy (RT). MATERIALS AND METHODS. A database search was performed to identify patients who had PAT develop after receiving RT. The CT characteristics of PAT, including the number, location, and appearance of filling defects as well as the presence of associated lung fibrosis, were recorded. The terminology (in situ thrombosis vs acute or chronic pulmonary embolism) used by the interpreting radiologists to describe PAT, the time between the completion of RT and development of PAT, the change in the size of the PAT, and observation of any new thrombi and emboli on follow-up imaging, were also recorded. RESULTS. Of the 27 patients in the study cohort, 22 (81%) had lung cancer and five (19%) had mesothelioma. Most PATs were solitary (93%) and nonocclusive (96%) and formed an obtuse angle to the vessel wall (89%). All PATs were eccentric within the involved PA and were located within the RT volume. The time from completion of RT to initial diagnosis of PAT on CT ranged from 53 to 2522 days (mean, 675 days). Radiation-induced lung fibrosis was present in the ipsilateral lung in all patients. No evidence of additional PA filling defects that suggested embolization were seen on follow-up images of any of the patients, even those who did not receive anticoagulant therapy. CONCLUSION. In situ PAT associated with RT, which to our knowledge has not previously been described in the English literature, has imaging features different from those of acute pulmonary emboli and does not appear to embolize. Radiologist awareness of PAT can facilitate accurate diagnosis and impact management.

The Influence of Speed on kerf width using PA to Optimize the Quality of 1mm Copper Sheets

Copper is widely used in industry where it has a number of varied applications. Nowadays, various methods are used in productive industries to provide the fastest, cheapest, and most effective solutions in facilitating cutting operations with minimal surface deformation. The study aims to examine the effect of speed on the kerf width to optimize the quality of 1 mm Cu surfaces using Plasma Arc Cutting Machining (PACM). The study used the experimental approach in performing cutting machining a number of 13 specimens with different cutting speeds from lowest to highest and using the same ampere for all experiments. The main objective is to study the effect of speed on the cutting quality. The design of the cutting path included the straight line and the angle resulting from the convergence of the vertical line with the curve of the circle, the obtuse angle, right and acute angle, the curved line and the angle resulting from the convergence of the horizontal line with the curve of the circle. A number of 18 points were assigned and measured and kerf width readings were recorded for all points on the path. The results of the measurement readings for the samples were compared, discussed and represented graphically to determine the speeds that can be used to obtain good cutting quality. Among the most important results of the study, the cutting speed increased at the beginning of the cutting path and resulted in a lower kerf width. This had a clear effect and increased the cutting quality. At the angle resulting from the convergence of the vertical line and the curve of the circle, the cut resulted in a greater kerf width. When the cutting speed decreased, the kerf width increased and the cutting quality decreased. The points on the circumference of the circle on the cutting path also recorded lower width values, lower than the mean values ​​at higher speeds.

The Effect of Age on Fat Distribution in the Neck Using Volumetric Computed Tomography.

Neck fat distribution plays an important role in aging, yet how fat distribution changes with age is largely unknown. This study used volumetric computed tomography in live patients to characterize neck fat volume and distribution in young and elderly women. A retrospective analysis was conducted of head and neck computed tomographic angiographs of 20 young (aged 20 to 35 years) and 20 old (aged 65 to 89 years) women. Fat volume in the supraplatysmal and subplatysmal planes was quantified. Distribution of fat volume was assessed by dividing each supraplatysmal and subplatysmal compartment into upper, middle, and lower thirds. Total supraplatysmal fat volume was greater than subplatysmal in all patients. Young patients had more total supraplatysmal fat than old patients (p < 0.0001). No difference was found between age groups in subplatysmal fat (p > 0.05). No difference was found between upper/middle/lower third supraplatysmal fat volumes in young patients. When comparing supraplatysmal thirds within the elderly population, the middle third fat volume (28.58 ± 20.01 cm3) was greater than both upper (18.93 ± 10.35 cm3) and lower thirds (15.46 ± 11.57 cm3) (p < 0.01). This study suggests that total supraplatysmal fat volume decreases with age. Older patients had more fat volume in the upper and middle thirds compared with the lower third of the supraplatysmal fat compartment, whereas young patients had more evenly distributed fat. These results suggest that fat deposition and redistribution in the neck occur with age and may be a contributing factor to the obtuse cervicomandibular angle of the elderly.

Efficacy of radiofrequency ablation for recurrent thyroid cancer invading the airways.

To evaluate the efficacy of radiofrequency ablation (RFA) in patients with recurrent thyroid cancer invading the airways. We reviewed patients who had undergone RFA for recurrent thyroid cancer in the central compartment after total thyroidectomy between January 2008 and December 2018. All tumors were classified according to their association with the laryngeal structure and trachea. The volume reduction rate (VRR) and complete disappearance rate were calculated, and their differences were determined relative to the association between the tumor and trachea. Complication rates associated with RFA were evaluated. The study population included 119 patients with 172 recurrent tumors. Mean VRR was 81.2% ± 55.7%, with 124 tumors (72.1%) completely disappearing after a mean follow-up of 47.9 ± 35.4 months. The complete disappearance rate of recurrent tumors not in contact with the trachea was highest, followed by tumors forming acute angles, right angles, and obtuse angles with the trachea, and tumors with intraluminal tracheal invasion (p value < 0.001). The overall complication rate was 21.4%. RFA is effective and safe for the local control of recurrent tumors in the central neck compartment after total thyroidectomy, even for tumors invading the airways, and may be considered an alternative to surgical resection. The inverse relationship between RFA efficacy and airway invasion suggests that early RFA may benefit patients with recurrent tumors in the central neck compartment. • RFA achieved a mean VRR of 81.2% ± 55.7% and complete disappearance of 124 tumors (72.1%) after a mean follow-up of 47.9 ± 35.4 months. • The complete disappearance rate of recurrent tumors not in contact with the trachea was the highest, followed by tumors forming acute angles, right angles, and obtuse angles with the trachea, and tumors with intraluminal tracheal invasion. • Stent-assisted RFA may be a good alternative for palliative treatment of recurrent tumors with intraluminal tracheal invasion.

Diagonal Compression Test of Mortar Interlocking Masonry Walls With Various Block Shapes and Different Support Conditions

The collapse of masonry buildings has caused numerous fatalities during past earthquakes. To reduce casualties due to earthquakes, the reinforcement of masonry buildings is necessary. Since masonry buildings are still used due to the low cost of the building materials, cheap reinforcement measures are desirable. Therefore, this study investigates the use and shape of the interlocking blocks instead of the regular rectangular blocks to increase the strength of masonry buildings without using expensive reinforcing materials. First, diagonal compression tests of masonry walls made of interlocking blocks with various shapes under different support conditions were conducted. Regarding the block shapes, two types of I-shaped blocks and two types of hourglass-shaped blocks were compared. For the support conditions, glued and contact conditions were compared. Next, finite element analysis was conducted to understand the mechanism. From the experiment and the finite element analysis, a similar tendency was observed. The walls made of I-shaped blocks with a right angle have less strength than the I-shaped block walls with an obtuse angle and the two hourglass-shaped block walls. It was also found that the support condition has a slight effect on the results of the I-shaped block wall with a right angle but large effect on the results of the other three block walls where the wall under the contact condition has larger strength than the wall under the glued condition. The strain was locally concentrated where the adjacent blocks interlock with each other or the block interlocks with the jig, and failure occurred at the area where the strain was concentrated. Strength can be increased by changing the block shape with less interlocking effect such as the I-shaped block walls with an obtuse angle or hourglass-shaped block walls. However, the displacement increases due to the dislocation and rotation of blocks as the interlocking effect decreases.

Synergistic inhibition effect of walnut green husk extract and sodium lignosulfonate on the corrosion of cold rolled steel in phosphoric acid solution

The synergistic inhibition effect of walnut green husk extract (WGHE) and sodium lignosulfonate (SLS) on the corrosion of cold rolled steel (CRS) in 3.0 M H3PO4 solution was firstly studied by weight loss, electrochemical technique, surface analysis, quantum chemical calculation and molecular dynamics (MD) simulation. Results show that WGHE acts as a moderate inhibitor with a maximum inhibition efficiency of 73.4%, while SLS is poor inhibitor with the maximum inhibition below 40%. Mixing WGHE with SLS produces strong synergistic inhibition effect, and can significantly improve the inhibitive performance with a pleasant maximum inhibition efficiency of 97.2%. The synergism parameter is high than unity, and increases with the inhibitor concentration, but decreases with an increase of temperature. The adsorption of WGHE, SLS or WGHE/SLS obeys Langmuir adsorption isotherm. Individual WGHE or SLS mainly retards cathodic reaction, while WGHE/SLS mixture drastically inhibits both anodic and cathodic reactions simultaneously. The charge transfer resistance is drastically increased for the WGHE/SLS mixture, but the double electric capacitance decreases to more extent. The inhibited CRS surface by WGHE/SLS clearly appears little corrosion from SEM graph, and is of hydrophobic nature with an obtuse contact angle. Two components of naphthoquinone and 2-phenylchromone in WGHE exhibit synergistic inhibition with SLS. Quantum chemical calculations are well accordance with the expected inhibition order of WGHE/SLS > WGHE > SLS. The WGHE/SLS hybrid co-adsorb on Fe (001) and Fe (110) surfaces in the nearly flat manner, and the adsorption energy is more negative comparing with individual WGHE or SLS.

Pattern Directive Sensing Selectivity of Graphene for Wearable Multifunctional Sensors via Femtosecond Laser Fabrication

AbstractGraphene has great potential in wearable sensors. However, the sensing selectivity of graphene‐based sensors is still a big challenge, limiting their application in the multifunctional sensors. Herein, different types and distributions of defects are introduced into graphene by femtosecond laser patterning to realize sensing selectivity for wearable multifunctional sensors. The imperfect graphene with four pattern arrays, circle, square, triangle, and hexagon with none, right, acute, and obtuse angle, is fabricated by laser to control the types and distributions of defects. The graphene with different patterns shows remarkable sensing selectivity, owing to the dangling bonds and vacancies on the edge of patterns. The graphene‐based sensor with the circle pattern array is used to detect the strain variation; the triangle one is for temperature detection; and the hexagon one can collect the information of gas. The gauge factor is demonstrated to be as high as ≈104. The as‐produced sensor with the above‐mentioned four patterns can simultaneously detect body pulse, temperature, and harmful gas by attaching to human body or clothes, offering real‐time health monitoring and protection. The patterned graphene‐based sensors with high sensing selectivity are expected to develop multifunctional sensor platform and versatile artificial electronic skin.

Interaction of the craniofacial complex and velopharyngeal musculature on speech resonance in children with 22q11.2 deletion syndrome: An MRI analysis

There are limited MRI studies of craniofacial and velopharyngeal features in children with 22q11.2 deletion syndrome (22q11.2DS) and to date, none have explored the potential relationship between these features and the speech phenotype. The purpose of this study was to examine the relationship between craniofacial and related velopharyngeal structures in children with 22q11.2DS and to assess their correlation to resonance features using an unsedated MRI protocol. Fifteen children with 22q11.2DS and 15 age- and sex-matched controls with normal velopharyngeal anatomy (ages 4-12 years) successfully completed the study. Analysis of covariance was used to compare differences between the experimental (22q11.2DS) and control (children with normal anatomy) groups. Correlation analyses and regression models were also utilized. The 22q11.2DS group demonstrated significantly shorter nasion-to-sella, sella-to-basion, and basion-to-opisthion distances. The anterior cranial base angle was significantly more obtuse. The levator veli palatini (levator) muscle was significantly thinner and shorter, with an obtuse angle of origin in the 22q11.2DS group. Levator length was significantly correlated with the sella-to-basion measure and hypernasality was correlated with levator origin-to-origin distance. Preliminary results from this study indicate a significant association between hypernasality and levator origin-to-origin distance. Findings from the present study, provide an insight into the pathophysiology of velopharyngeal dysfunction related to this clinically complex population.

Effect of machined surface texture on fretting crack nucleation under radial loading in conformal contact

This paper presented the influence of machined surface texture on fretting cracks behaviors of Titanium alloy Ti–6Al–4V under radial loading in conformal contact. The contacted holes of specimen were machined with combined helical and flank milling before fretting fatigue tests, and a special fretting fatigue test apparatus was proposed to focus on conformal contact fretting fatigue (CCFF) test under radial loading. The test results showed that all the specimens failed at the contact area where characterizes an inner obtuse angle between the material flow direction (or cutting direction) and the direction of the tangential component of the contact force. The area with higher surface skewness and kurtosis values was also prone to nucleate fretting fatigue crack. These results suggested that the corresponding machining conditions in hole-making and surface strengthen processes should be adjusted to guide the production of surface texture properties, in terms of obtaining desirable lower skewness and kurtosis features to relieve nucleation of fretting cracks. Additionally, the debris in conformal contact tended to aggregate towards the partial slip zone (PSZ) due to the conformal geometry and form a compacted layer in the gross slip zone (GSZ) subjected to radial loading. These characteristics exacerbated and alleviated fretting damage in the PSZ and GSZ, respectively. In this research, a set of suitable milling parameters for the hole flank milling process in terms of prolonging fretting fatigue life were also defined.

Archaeogaia macachaae gen. et sp. nov., one of the oldest Notoungulata Roth, 1903 from the early-middle Paleocene Mealla Formation (Central Andes, Argentina) with insights into the Paleocene-Eocene south American biochronology

In this contribution, we report the discovery of Archaeogaia macachaae gen. et sp. nov., one of the oldest notoungulate recovered from the upper section of Mealla Formation in the Tonco Valley (Northwestern Argentina, Salta Province). The new material consists on a left mandibular fragment with damaged m1 and complete m2-3. Archaeogaia macachaae is characterized by the following combination of features: m1 slightly shorter than m2 and both larger than m3; brachydont molars; talonid mesio-distally shorter than trigonid; metaconid slightly taller than protoconid and distally placed; reduced paraconid in m2; metalophid straight in m2–3, but it runs mesially forming a slightly obtuse angle in the labial edge in m2, whereas it is more transverse in m3; transverse entolophid; mesial cingulid extending from the middle to the lingual face of molars; and distal cingulid connecting the hypoconulid with the mesial face of the entoconid on m2–3. We perform a phylogenetic analysis based on a data matrix composed of 147 craniodental characters and 70 taxa. The analysis yields 6104 most parsimonious trees of 423 steps each. In the strict consensus previously well-supported clades collapse into a polytomy; and Archaeogaia is positioned within the order Notoungulata based on two synapomorphies: a) presence of a transverse entolophid, and b) lower cheek teeth with short mesio-distal protolophid, transverse metalophid and mesio-distal hypolophid slightly convex labially. The former character was recovered as a synapomorphy for Notoungulata in several previous studies. According to the reduced consensus, Archaeogaia occupies different positions within the order; these fluctuating locations could be the result of the presence of plesiomorphic features in the holotype, and the absence of the structures that define the notoungulate clades in which the new taxon is located. The paleomagnetic data indicates that the Mealla Formation was deposited during Chron 27r to the base of Chron 26r (latest Danian-earliest Selandian). In this context, we discuss the finding of Archaeogaia, and the age of Mealla Formation in the South American biochronology.

Eksplorasi Etnomatematika Motif Batik Gonggong Tanjungpinang Kepulauan Riau

Batik is a culture of the archipelago in Indonesia, where batik has its own characteristics, one of which is barking batik in Tanjungpinang City, Kepulauan Riau Province. In the batik motif there is an indication of mathematical practice, especially in the batik motif. Mathematical practice in this culture is known as ethnomatematics. This study aims to explore ethnomatemics on the batik motifs of Tanjungpinang, Kepulauan Riau Province . This type of research is qualitative with an ethnographic approach. Research data is done through observation, interviews and documentation. The main instrument of research is the researcher himself. Then the data are analyzed by referring to Van Maanen by reducing data, data presentation and conclusions. The results showed a mathematical practice of the bark batik motifs in the form of the concept of folding symmetry, acute angles, obtuse angles, translational concepts, and circular planes.