Foot placement modification for a biped humanoid robot with narrow feet.

PubMed

Hashimoto, Kenji; Hattori, Kentaro; Otani, Takuya; Lim, Hun-Ok; Takanishi, Atsuo

2014-01-01

This paper describes a walking stabilization control for a biped humanoid robot with narrow feet. Most humanoid robots have larger feet than human beings to maintain their stability during walking. If robot's feet are as narrow as humans, it is difficult to realize a stable walk by using conventional stabilization controls. The proposed control modifies a foot placement according to the robot's attitude angle. If a robot tends to fall down, a foot angle is modified about the roll axis so that a swing foot contacts the ground horizontally. And a foot-landing point is also changed laterally to inhibit the robot from falling to the outside. To reduce a foot-landing impact, a virtual compliance control is applied to the vertical axis and the roll and pitch axes of the foot. Verification of the proposed method is conducted through experiments with a biped humanoid robot WABIAN-2R. WABIAN-2R realized a knee-bended walking with 30 mm breadth feet. Moreover, WABIAN-2R mounted on a human-like foot mechanism mimicking a human's foot arch structure realized a stable walking with the knee-stretched, heel-contact, and toe-off motion.

Operation analysis of a Chebyshev-Pantograph leg mechanism for a single DOF biped robot

NASA Astrophysics Data System (ADS)

Liang, Conghui; Ceccarelli, Marco; Takeda, Yukio

2012-12-01

In this paper, operation analysis of a Chebyshev-Pantograph leg mechanism is presented for a single degree of freedom (DOF) biped robot. The proposed leg mechanism is composed of a Chebyshev four-bar linkage and a pantograph mechanism. In contrast to general fully actuated anthropomorphic leg mechanisms, the proposed leg mechanism has peculiar features like compactness, low-cost, and easy-operation. Kinematic equations of the proposed leg mechanism are formulated for a computer oriented simulation. Simulation results show the operation performance of the proposed leg mechanism with suitable characteristics. A parametric study has been carried out to evaluate the operation performance as function of design parameters. A prototype of a single DOF biped robot equipped with two proposed leg mechanisms has been built at LARM (Laboratory of Robotics and Mechatronics). Experimental test shows practical feasible walking ability of the prototype, as well as drawbacks are discussed for the mechanical design.

An asymptotic solution to a passive biped walker model

NASA Astrophysics Data System (ADS)

Yudaev, Sergey A.; Rachinskii, Dmitrii; Sobolev, Vladimir A.

2017-02-01

We consider a simple model of a passive dynamic biped robot walker with point feet and legs without knee. The model is a switched system, which includes an inverted double pendulum. Robot’s gait and its stability depend on parameters such as the slope of the ramp, the length of robot’s legs, and the mass distribution along the legs. We present an asymptotic solution of the model. The first correction to the zero order approximation is shown to agree with the numerical solution for a limited parameter range.

Spatio-temporal features for tracking and quadruped/biped discrimination

NASA Astrophysics Data System (ADS)

Rickman, Rick; Copsey, Keith; Bamber, David C.; Page, Scott F.

2012-05-01

Techniques such as SIFT and SURF facilitate efficient and robust image processing operations through the use of sparse and compact spatial feature descriptors and show much potential for defence and security applications. This paper considers the extension of such techniques to include information from the temporal domain, to improve utility in applications involving moving imagery within video data. In particular, the paper demonstrates how spatio-temporal descriptors can be used very effectively as the basis of a target tracking system and as target discriminators which can distinguish between bipeds and quadrupeds. Results using sequences of video imagery of walking humans and dogs are presented, and the relative merits of the approach are discussed.

Generation of the Human Biped Stance by a Neural Controller Able to Compensate Neurological Time Delay

PubMed Central

Jiang, Ping; Chiba, Ryosuke; Takakusaki, Kaoru; Ota, Jun

2016-01-01

The development of a physiologically plausible computational model of a neural controller that can realize a human-like biped stance is important for a large number of potential applications, such as assisting device development and designing robotic control systems. In this paper, we develop a computational model of a neural controller that can maintain a musculoskeletal model in a standing position, while incorporating a 120-ms neurological time delay. Unlike previous studies that have used an inverted pendulum model, a musculoskeletal model with seven joints and 70 muscular-tendon actuators is adopted to represent the human anatomy. Our proposed neural controller is composed of both feed-forward and feedback controls. The feed-forward control corresponds to the constant activation input necessary for the musculoskeletal model to maintain a standing posture. This compensates for gravity and regulates stiffness. The developed neural controller model can replicate two salient features of the human biped stance: (1) physiologically plausible muscle activations for quiet standing; and (2) selection of a low active stiffness for low energy consumption. PMID:27655271

Postural stability of biped robots and the foot-rotation indicator (FRI) point

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goswami, A.

1999-06-01

The focus of this paper is the problem of foot rotation in biped robots during the single-support phase. Foot rotation is an indication of postural instability, which should be carefully treated in a dynamically stable walk and avoided altogether in a statically stable walk. The author introduces the foot-rotation indicator (FRI) point, which is a point on the foot/ground-contact surface where the net ground-reaction force would have to act to keep the foot stationary. To ensure no foot rotation, the FRI point must remain within the convex hull of the foot-support area. In contrast with the ground projection of themore » center of mass (GCoM), which is a static criterion, the FRI point incorporates robot dynamics. As opposed to the center of pressure (CoP) -- better known as the zero-moment point (ZMP) in the robotics literature -- which may not leave the support area, the FRI point may leave the area. In fact, the position of the FRI point outside the footprint indicates the direction of the impending rotation and the magnitude of rotational moment acting on the foot. Owing to these important properties, the FRI point helps not only to monitor the state of postural stability of a biped robot during the entire gait cycle, but indicates the severity of instability of the gait as well. In response to a recent need, the paper also resolves the misconceptions surrounding the CoP/ZMP equivalence.« less

Note: Reconfigurable pelvis mechanism for efficient multi-locomotion: Biped and quadruped walking

NASA Astrophysics Data System (ADS)

Yoon, Byungho; Kim, Soohyun

2017-12-01

A reconfigurable pelvis mechanism that can change its length for multi-locomotion robot is introduced. From the characteristics of animals that walk in a bipedal or quadrupedal manner, we found that the length of the pelvis for each type of locomotion is related to the efficiency and stability of walking. We demonstrated the effectiveness of this mechanism in biped and quadruped walking through comparison of accumulated power of consumption. We also examined the changes of the supporting polygon according to the length of the pelvis during quadruped walking in terms of stability.

Note: Reconfigurable pelvis mechanism for efficient multi-locomotion: Biped and quadruped walking.

PubMed

Yoon, Byungho; Kim, Soohyun

2017-12-01

A reconfigurable pelvis mechanism that can change its length for multi-locomotion robot is introduced. From the characteristics of animals that walk in a bipedal or quadrupedal manner, we found that the length of the pelvis for each type of locomotion is related to the efficiency and stability of walking. We demonstrated the effectiveness of this mechanism in biped and quadruped walking through comparison of accumulated power of consumption. We also examined the changes of the supporting polygon according to the length of the pelvis during quadruped walking in terms of stability.

Pareto Design of State Feedback Tracking Control of a Biped Robot via Multiobjective PSO in Comparison with Sigma Method and Genetic Algorithms: Modified NSGAII and MATLAB's Toolbox

PubMed Central

Mahmoodabadi, M. J.; Taherkhorsandi, M.; Bagheri, A.

2014-01-01

An optimal robust state feedback tracking controller is introduced to control a biped robot. In the literature, the parameters of the controller are usually determined by a tedious trial and error process. To eliminate this process and design the parameters of the proposed controller, the multiobjective evolutionary algorithms, that is, the proposed method, modified NSGAII, Sigma method, and MATLAB's Toolbox MOGA, are employed in this study. Among the used evolutionary optimization algorithms to design the controller for biped robots, the proposed method operates better in the aspect of designing the controller since it provides ample opportunities for designers to choose the most appropriate point based upon the design criteria. Three points are chosen from the nondominated solutions of the obtained Pareto front based on two conflicting objective functions, that is, the normalized summation of angle errors and normalized summation of control effort. Obtained results elucidate the efficiency of the proposed controller in order to control a biped robot. PMID:24616619

Comparison of kinematic and dynamic leg trajectory optimization techniques for biped robot locomotion

NASA Astrophysics Data System (ADS)

Khusainov, R.; Klimchik, A.; Magid, E.

2017-01-01

The paper presents comparison analysis of two approaches in defining leg trajectories for biped locomotion. The first one operates only with kinematic limitations of leg joints and finds the maximum possible locomotion speed for given limits. The second approach defines leg trajectories from the dynamic stability point of view and utilizes ZMP criteria. We show that two methods give different trajectories and demonstrate that trajectories based on pure dynamic optimization cannot be realized due to joint limits. Kinematic optimization provides unstable solution which can be balanced by upper body movement.

Under the radar: mitigating enigmatic ecological impacts.

PubMed

Raiter, Keren G; Possingham, Hugh P; Prober, Suzanne M; Hobbs, Richard J

2014-11-01

Identifying the deleterious ecological effects of developments, such as roads, mining, and urban expansion, is essential for informing development decisions and identifying appropriate mitigation actions. However, there are many types of ecological impacts that slip 'under the radar' of conventional impact evaluations and undermine the potential for successful impact mitigation (including offsets). These 'enigmatic' impacts include those that are small but act cumulatively; those outside of the area directly considered in the evaluation; those not detectable with the methods, paradigms, or spatiotemporal scales used to detect them; those facilitated, but not directly caused, by development; and synergistic impact interactions. Here, we propose a framework for conceptualising enigmatic impacts and discuss ways to address them. Copyright © 2014 Elsevier Ltd. All rights reserved.

The link between rapid enigmatic amphibian decline and the globally emerging chytrid fungus.

PubMed

Lötters, Stefan; Kielgast, Jos; Bielby, Jon; Schmidtlein, Sebastian; Bosch, Jaime; Veith, Michael; Walker, Susan F; Fisher, Matthew C; Rödder, Dennis

2009-09-01

Amphibians are globally declining and approximately one-third of all species are threatened with extinction. Some of the most severe declines have occurred suddenly and for unknown reasons in apparently pristine habitats. It has been hypothesized that these "rapid enigmatic declines" are the result of a panzootic of the disease chytridiomycosis caused by globally emerging amphibian chytrid fungus. In a Species Distribution Model, we identified the potential distribution of this pathogen. Areas and species from which rapid enigmatic decline are known significantly overlap with those of highest environmental suitability to the chytrid fungus. We confirm the plausibility of a link between rapid enigmatic decline in worldwide amphibian species and epizootic chytridiomycosis.

Eta Carinae: Enigmatic Eta Carinae

NASA Astrophysics Data System (ADS)

Pittard, J. M.

2003-02-01

Eta Carinae is perhaps the most massive and luminous star in our galaxy, and is also one of the most enigmatic. Despite over a century and a half of study since an enormous eruption which expelled several solar masses of material into interstellar space, and which guaranteed its infamy, astronomers have struggled to understand its true nature. With a key event in the cycle of this star expected during the summer of 2003, an unprecedented programme of observations has been organized by astronomers around the world. Eta Carinae may at last be about to reveal some of its most fundamental secrets.

Who killed Laius?: On Sophocles' enigmatic message.

PubMed

Priel, Beatriz

2002-04-01

Using Laplanche's basic conceptualisation of the role of the other in unconscious processes, the author proposes a reading of Sophocles' tragedy, Oedipus the King, according to basic principles of dream interpretation. This reading corroborates contemporary literary perspectives suggesting that Sophocles' tragedy may not only convey the myth but also provide a critical analysis of how myths work. Important textual inconsistencies and incoherence, which have been noted through the centuries, suggest the existence of another, repressed story. Moreover, the action of the play points to enigmatic parental messages of infanticide and the silencing of Oedipus's story, as well as their translation into primordial guilt, as the origins of the tragic denouement. Oedipus's self-condemnation of parricide follows these enigmatic codes and is unrelated to, and may even contradict, the evidence offered in the tragedy as to the identity of Laius's murderers. Moreover, Sophocles' text provides a complex intertwining of hermeneutic and deterministic perspectives. Through the use of the mythical deterministic content, the formal characteristics of Sophocles' text, mainly its complex time perspective and extensive use of double meaning, dramatise in the act of reading an acute awareness of interpretation. This reading underscores the fundamental role of the other in the constitution of unconscious processes.

Dimerization deficiency of enigmatic retinitis pigmentosa-linked rhodopsin mutants

PubMed Central

Ploier, Birgit; Caro, Lydia N.; Morizumi, Takefumi; Pandey, Kalpana; Pearring, Jillian N.; Goren, Michael A.; Finnemann, Silvia C.; Graumann, Johannes; Arshavsky, Vadim Y.; Dittman, Jeremy S.; Ernst, Oliver P.; Menon, Anant K.

2016-01-01

Retinitis pigmentosa (RP) is a blinding disease often associated with mutations in rhodopsin, a light-sensing G protein-coupled receptor and phospholipid scramblase. Most RP-associated mutations affect rhodopsin's activity or transport to disc membranes. Intriguingly, some mutations produce apparently normal rhodopsins that nevertheless cause disease. Here we show that three such enigmatic mutations—F45L, V209M and F220C—yield fully functional visual pigments that bind the 11-cis retinal chromophore, activate the G protein transducin, traffic to the light-sensitive photoreceptor compartment and scramble phospholipids. However, tests of scramblase activity show that unlike wild-type rhodopsin that functionally reconstitutes into liposomes as dimers or multimers, F45L, V209M and F220C rhodopsins behave as monomers. This result was confirmed in pull-down experiments. Our data suggest that the photoreceptor pathology associated with expression of these enigmatic RP-associated pigments arises from their unexpected inability to dimerize via transmembrane helices 1 and 5. PMID:27694816

Dimerization deficiency of enigmatic retinitis pigmentosa-linked rhodopsin mutants

NASA Astrophysics Data System (ADS)

Ploier, Birgit; Caro, Lydia N.; Morizumi, Takefumi; Pandey, Kalpana; Pearring, Jillian N.; Goren, Michael A.; Finnemann, Silvia C.; Graumann, Johannes; Arshavsky, Vadim Y.; Dittman, Jeremy S.; Ernst, Oliver P.; Menon, Anant K.

2016-10-01

Retinitis pigmentosa (RP) is a blinding disease often associated with mutations in rhodopsin, a light-sensing G protein-coupled receptor and phospholipid scramblase. Most RP-associated mutations affect rhodopsin's activity or transport to disc membranes. Intriguingly, some mutations produce apparently normal rhodopsins that nevertheless cause disease. Here we show that three such enigmatic mutations--F45L, V209M and F220C--yield fully functional visual pigments that bind the 11-cis retinal chromophore, activate the G protein transducin, traffic to the light-sensitive photoreceptor compartment and scramble phospholipids. However, tests of scramblase activity show that unlike wild-type rhodopsin that functionally reconstitutes into liposomes as dimers or multimers, F45L, V209M and F220C rhodopsins behave as monomers. This result was confirmed in pull-down experiments. Our data suggest that the photoreceptor pathology associated with expression of these enigmatic RP-associated pigments arises from their unexpected inability to dimerize via transmembrane helices 1 and 5.

Optimal foot shape for a passive dynamic biped.

PubMed

Kwan, Maxine; Hubbard, Mont

2007-09-21

Passive walking dynamics describe the motion of a biped that is able to "walk" down a shallow slope without any actuation or control. Instead, the walker relies on gravitational and inertial effects to propel itself forward, exhibiting a gait quite similar to that of humans. These purely passive models depend on potential energy to overcome the energy lost when the foot impacts the ground. Previous research has demonstrated that energy loss at heel-strike can vary widely for a given speed, depending on the nature of the collision. The point of foot contact with the ground (relative to the hip) can have a significant effect: semi-circular (round) feet soften the impact, resulting in much smaller losses than point-foot walkers. Collisional losses are also lower if a single impulse is broken up into a series of smaller impulses that gradually redirect the velocity of the center of mass rather than a single abrupt impulse. Using this principle, a model was created where foot-strike occurs over two impulses, "heel-strike" and "toe-strike," representative of the initial impact of the heel and the following impact as the ball of the foot strikes the ground. Having two collisions with the flat-foot model did improve efficiency over the point-foot model. Representation of the flat-foot walker as a rimless wheel helped to explain the optimal flat-foot shape, driven by symmetry of the virtual spoke angles. The optimal long period foot shape of the simple passive walking model was not very representative of the human foot shape, although a reasonably anthropometric foot shape was predicted by the short period solution.

Real-time physics-based 3D biped character animation using an inverted pendulum model.

PubMed

Tsai, Yao-Yang; Lin, Wen-Chieh; Cheng, Kuangyou B; Lee, Jehee; Lee, Tong-Yee

2010-01-01

We present a physics-based approach to generate 3D biped character animation that can react to dynamical environments in real time. Our approach utilizes an inverted pendulum model to online adjust the desired motion trajectory from the input motion capture data. This online adjustment produces a physically plausible motion trajectory adapted to dynamic environments, which is then used as the desired motion for the motion controllers to track in dynamics simulation. Rather than using Proportional-Derivative controllers whose parameters usually cannot be easily set, our motion tracking adopts a velocity-driven method which computes joint torques based on the desired joint angular velocities. Physically correct full-body motion of the 3D character is computed in dynamics simulation using the computed torques and dynamical model of the character. Our experiments demonstrate that tracking motion capture data with real-time response animation can be achieved easily. In addition, physically plausible motion style editing, automatic motion transition, and motion adaptation to different limb sizes can also be generated without difficulty.

Correction: Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria.

PubMed

Evans, Nathaniel M; Lindner, Alberto; Raikova, Ekaterina V; Collins, Allen G; Cartwright, Paulyn

2009-07-15

Correction to Evans, N.M., Lindner, A., Raikova, E.V., Collins, A.G. and Cartwright, P. Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the phylum Cnidaria. BMC Evol Biol, 2008, 8:139.

Correction: Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria

PubMed Central

2009-01-01

Correction to Evans, N.M., Lindner, A., Raikova, E.V., Collins, A.G. and Cartwright, P. Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the phylum Cnidaria. BMC Evol Biol, 2008, 8:139. PMID:19604374

Lipid-sensors, enigmatic-orphan and orphan nuclear receptors as therapeutic targets in breast-cancer.

PubMed

Garattini, Enrico; Bolis, Marco; Gianni', Maurizio; Paroni, Gabriela; Fratelli, Maddalena; Terao, Mineko

2016-07-05

Breast-cancer is heterogeneous and consists of various groups with different biological characteristics. Innovative pharmacological approaches accounting for this heterogeneity are needed. The forty eight human Nuclear-Hormone-Receptors are ligand-dependent transcription-factors and are classified into Endocrine-Receptors, Adopted-Orphan-Receptors (Lipid-sensors and Enigmatic-Orphans) and Orphan-receptors. Nuclear-Receptors represent ideal targets for the design/synthesis of pharmacological ligands. We provide an overview of the literature available on the expression and potential role played by Lipid-sensors, Enigmatic-Orphans and Orphan-Receptors in breast-cancer. The data are complemented by an analysis of the expression levels of each selected Nuclear-Receptor in the PAM50 breast-cancer groups, following re-elaboration of the data publicly available. The major aim is to support the idea that some of the Nuclear-Receptors represent largely unexploited therapeutic-targets in breast-cancer treatment/chemo-prevention. On the basis of our analysis, we conclude that the Lipid-Sensors, NR1C3, NR1H2 and NR1H3 are likely to be onco-suppressors in breast-cancer. The Enigmatic-Orphans, NR1F1 NR2A1 and NR3B3 as well as the Orphan-Receptors, NR0B1, NR0B2, NR1D1, NR2F1, NR2F2 and NR4A3 exert a similar action. These Nuclear-Receptors represent candidates for the development of therapeutic strategies aimed at increasing their expression or activating them in tumor cells. The group of Nuclear-Receptors endowed with potential oncogenic properties consists of the Lipid-Sensors, NR1C2 and NR1I2, the Enigmatic-Orphans, NR1F3, NR3B1 and NR5A2, as well as the Orphan-Receptors, NR2E1, NR2E3 and NR6A1. These oncogenic Nuclear-Receptors should be targeted with selective antagonists, reverse-agonists or agents/strategies capable of reducing their expression in breast-cancer cells.

Minimal feedback to a rhythm generator improves the robustness to slope variations of a compass biped.

PubMed

Spitz, Jonathan; Evstrachin, Alexandrina; Zacksenhouse, Miriam

2015-08-20

In recent years there has been a growing interest in the field of dynamic walking and bio-inspired robots. However, while walking and running on a flat surface have been studied extensively, walking dynamically over terrains with varying slope remains a challenge. Previously we developed an open loop controller based on a central pattern generator (CPG). The controller applied predefined torque patterns to a compass-gait biped, and achieved stable gaits over a limited range of slopes. In this work, this range is greatly extended by applying a once per cycle feedback to the CPG controller. The terrain's slope is measured and used to modify both the CPG frequency and the torque amplitude once per step. A multi-objective optimization algorithm was used to tune the controller parameters for a simulated CB model. The resulting controller successfully traverses terrains with slopes ranging from +7° to -8°, comparable to most slopes found in human constructed environments. Gait stability was verified by computing the linearized Poincaré Map both numerically and analytically.

The enigmatic fire regime of coast redwood forests and why it matters

Treesearch

J. Morgan Varner; Erik S. Jules

2017-01-01

Of perhaps all forests in North America, the fire regime of coast redwoods (Sequoia sempervirens (D. Don) Endl.) is most enigmatic. Widely considered a temperate rainforest, a large number of fire history studies depict a forest dominated by frequent surface fire regimes. Coast redwood also has a long list of traits that allow it to persist and...

Enigmatic mounds in 'Subglacial Meltwater Corridors' on the Canadian Shield: a record of channelised, subglacial meltwater drainage during Laurentide deglaciation

NASA Astrophysics Data System (ADS)

Haiblen, Anna; Ward, Brent; Normandeau, Philippe; Campbell, Janet

2017-04-01

Esker networks have traditionally been invoked to represent the channelised subglacial drainage system in shield terrains. However, eskers are only one landform found within 'subglacial meltwater corridors' (SMCs) on the Canadian Shield. SMCs are tracts where till has been eroded, bedrock is exposed, and glaciofluvial sediments have been deposited. SMCs are regularly spaced, parallel deglacial ice-flow directions, have undulating longitudinal profiles, and cross modern drainage divides. Our lidar- and field-based mapping near Lac de Gras, Northwest Territories, west of the Keewatin Ice Divide (KID), reveals that eskers are not present in the majority of SMCs. Instead, enigmatic mounds are commonly the dominant landform type. Enigmatic mounds typically occur in groups of 20 to 200. They are commonly composed of sandy diamicton that is coarser grained and better sorted than regional till. This diamicton is occasionally draped with well-sorted, stratified glaciofluvial sediments. Some enigmatic mounds have a single highpoint (individual mounds) while others have a complex, irregular form (complex mounds). Individual mounds have an average long-axis length of 43 m and an average height of < 2 m, however, their size is highly variable: the largest mounds are 170 m long and 15 m high. Complex mounds are typically larger than individual mounds. Our morphometric analysis shows that individual mounds have a mean length-to-width ratio of 1.8. The average mound elongation direction parallels the final ice flow that affected the area. However, where meltwater- and ice-flow directions differ, mound long-axis orientations typically cluster about meltwater flow directions. We have also observed SMCs and enigmatic mounds in the South Rae region of Northwest Territories, 450 km SE of Lac de Gras. Multiple types of enigmatic mounds are present in this area: some are similar to those near Lac de Gras, some are composed of till, and some are composed of sorted and stratified sediments

Cloning and expression characterization of peroxisome proliferator-activated receptors (PPARs) with their agonists, dietary lipids, and ambient salinity in rabbitfish Siganus canaliculatus.

PubMed

You, Cuihong; Jiang, Danli; Zhang, Qinghao; Xie, Dizhi; Wang, Shuqi; Dong, Yewei; Li, Yuanyou

2017-04-01

Rabbitfish Siganus canaliculatus is the first marine teleost reported to have the ability of biosynthesizing C 20-22 long-chain polyunsaturated fatty acids (LC-PUFA) from C 18 precursors, and thus provides a model for studying the regulatory mechanisms of LC-PUFA biosynthesis in teleosts. To investigate the possible roles of peroxisome proliferator-activated receptors (PPARs), critical transcription factors involved in the regulation of lipid metabolism, in the regulation of LC-PUFA biosynthesis in rabbitfish, the PPAR genes were cloned and their expression characterization with PPAR agonists, dietary lipid resource, and ambient salinity were examined. Three cDNA sequences respectively encoding 477, 516 and 519 amino acids of PPARα, PPARβ, and PPARγ isoforms were obtained. PPARα exhibited a wide tissue expression with its highest levels in the heart and brain; PPARβ was predominantly expressed in the gills, while PPARγ was highly expressed in the intestine and gills. In rabbitfish primary hepatocytes, both the PPAR agonists 2-bromopalmitate (2-Bro) and fenofibrate (FF) increased the expression of PPARγ, SREBP1c and Elovl5, whereas FF depressed the expression of Δ6/Δ5 Fad. Moreover, a higher hepatic PPARβ expression was observed in fish fed diets with vegetable oils (VO) than that with fish oil (FO), in the former the expression of PPARα, PPARβ, and PPARγ were increased at the low ambient salinity (10ppt), where an increasing expression of Δ5/Δ6 Fad, Δ4 Fad and Elovl5 genes was previously reported. These results suggest that PPARs might be involved in the upregulation of LC-PUFA biosynthesis with dietary VO and low ambient salinity in rabbitfish. Copyright © 2017 Elsevier Inc. All rights reserved.

The enigmatic fast leaflet rotation in Desmodium motorium

PubMed Central

Lev-Yadun, Simcha

2013-01-01

I propose that the enigmatic leaflet movements in elliptical circles every few minutes of the Indian telegraph (semaphore) plant Desmodium motorium ( = D. gyrans = Hedysarum gyrans = Codariocalyx motorius), which has intrigued scientists for centuries, is a new type of butterfly or general winged arthropod mimicry by this plant. Such leaflet movement may deceive a passing butterfly searching for an un-occupied site suitable to deposit its eggs, that the plant is already occupied. It may also attract insectivorous birds, reptiles or arthropods to the plant because it looks as if it is harboring a potential prey and while they patrol there, they can find insects or other invertebrates that indeed attack the plant. The possibility that diurnal mammalian herbivores may also be deterred by these movements should not be dismissed. PMID:23603964

Adaptive, fast walking in a biped robot under neuronal control and learning.

PubMed

Manoonpong, Poramate; Geng, Tao; Kulvicius, Tomas; Porr, Bernd; Wörgötter, Florentin

2007-07-01

Human walking is a dynamic, partly self-stabilizing process relying on the interaction of the biomechanical design with its neuronal control. The coordination of this process is a very difficult problem, and it has been suggested that it involves a hierarchy of levels, where the lower ones, e.g., interactions between muscles and the spinal cord, are largely autonomous, and where higher level control (e.g., cortical) arises only pointwise, as needed. This requires an architecture of several nested, sensori-motor loops where the walking process provides feedback signals to the walker's sensory systems, which can be used to coordinate its movements. To complicate the situation, at a maximal walking speed of more than four leg-lengths per second, the cycle period available to coordinate all these loops is rather short. In this study we present a planar biped robot, which uses the design principle of nested loops to combine the self-stabilizing properties of its biomechanical design with several levels of neuronal control. Specifically, we show how to adapt control by including online learning mechanisms based on simulated synaptic plasticity. This robot can walk with a high speed (>3.0 leg length/s), self-adapting to minor disturbances, and reacting in a robust way to abruptly induced gait changes. At the same time, it can learn walking on different terrains, requiring only few learning experiences. This study shows that the tight coupling of physical with neuronal control, guided by sensory feedback from the walking pattern itself, combined with synaptic learning may be a way forward to better understand and solve coordination problems in other complex motor tasks.

Cloning and Characterization of Lxr and Srebp1, and Their Potential Roles in Regulation of LC-PUFA Biosynthesis in Rabbitfish Siganus canaliculatus.

PubMed

Zhang, Qinghao; You, Cuihong; Liu, Fang; Zhu, Wendi; Wang, Shuqi; Xie, Dizhi; Monroig, Óscar; Tocher, Douglas R; Li, Yuanyou

2016-09-01

Rabbitfish Siganus canaliculatus was the first marine teleost demonstrated to have the ability to biosynthesize C20-22 long-chain polyunsaturated fatty acid (LC-PUFA) from C18 PUFA precursors, which is generally absent or low in marine teleosts. Thus, understanding the molecular basis of LC-PUFA biosynthesis in rabbitfish will contribute to efforts aimed at optimizing LC-PUFA biosynthesis in teleosts, especially marine species. In the present study, the importance of the transcription factors liver X receptor (Lxr) and sterol regulatory element-binding protein 1 (Srebp1) in regulation of LC-PUFA biosynthesis in rabbitfish was investigated. First, full-length cDNA of Lxr and Srebp1 were cloned and characterized. The Lxr mRNA displayed a ubiquitous tissue expression pattern while Srebp1 was highly expressed in eyes, brain and intestine. In rabbitfish primary hepatocytes treated with Lxr agonist T0901317, the expression of Lxr and Srebp1 was activated, accompanied by elevated mRNA levels of Δ4 and Δ6/Δ5 fatty acyl desaturase (Fad), key enzymes of LC-PUFA biosynthesis, as well as peroxisome proliferator-activated receptor γ (PPARγ). In addition, Srebp1 displayed higher expression levels in liver of rabbitfish fed a vegetable oil diet or reared at 10 ppt salinity, which were conditions reported to increase the liver expression of Δ4 and Δ6/Δ5 Fad and LC-PUFA biosynthetic ability, than fish fed a fish oil diet or reared at 32 ppt, respectively. These results suggested that Lxr and Srebp1 are involved in regulation of LC-PUFA biosynthesis probably by promoting the expression of two Fad in rabbitfish liver, which, to our knowledge, is the first report in marine teleosts.

Using step width to compare locomotor biomechanics between extinct, non-avian theropod dinosaurs and modern obligate bipeds.

PubMed

Bishop, P J; Clemente, C J; Weems, R E; Graham, D F; Lamas, L P; Hutchinson, J R; Rubenson, J; Wilson, R S; Hocknull, S A; Barrett, R S; Lloyd, D G

2017-07-01

How extinct, non-avian theropod dinosaurs locomoted is a subject of considerable interest, as is the manner in which it evolved on the line leading to birds. Fossil footprints provide the most direct evidence for answering these questions. In this study, step width-the mediolateral (transverse) distance between successive footfalls-was investigated with respect to speed (stride length) in non-avian theropod trackways of Late Triassic age. Comparable kinematic data were also collected for humans and 11 species of ground-dwelling birds. Permutation tests of the slope on a plot of step width against stride length showed that step width decreased continuously with increasing speed in the extinct theropods ( p < 0.001), as well as the five tallest bird species studied ( p < 0.01). Humans, by contrast, showed an abrupt decrease in step width at the walk-run transition. In the modern bipeds, these patterns reflect the use of either a discontinuous locomotor repertoire, characterized by distinct gaits (humans), or a continuous locomotor repertoire, where walking smoothly transitions into running (birds). The non-avian theropods are consequently inferred to have had a continuous locomotor repertoire, possibly including grounded running. Thus, features that characterize avian terrestrial locomotion had begun to evolve early in theropod history. © 2017 The Author(s).

Hepatocyte Nuclear Factor 4α (HNF4α) Is a Transcription Factor of Vertebrate Fatty Acyl Desaturase Gene as Identified in Marine Teleost Siganus canaliculatus

PubMed Central

Dong, Yewei; Wang, Shuqi; Chen, Junliang; Zhang, Qinghao; Liu, Yang; You, Cuihong; Monroig, Óscar; Tocher, Douglas R.; Li, Yuanyou

2016-01-01

Rabbitfish Siganus canaliculatus was the first marine teleost demonstrated to have the capability of biosynthesizing long-chain polyunsaturated fatty acids (LC-PUFA) from C18 precursors, and to possess a Δ4 fatty acyl desaturase (Δ4 Fad) which was the first report in vertebrates, and is a good model for studying the regulatory mechanisms of LC-PUFA biosynthesis in teleosts. In order to understand regulatory mechanisms of transcription of Δ4 Fad, the gene promoter was cloned and characterized in the present study. An upstream sequence of 1859 bp from the initiation codon ATG was cloned as the promoter candidate. On the basis of bioinformatic analysis, several binding sites of transcription factors (TF) including GATA binding protein 2 (GATA-2), CCAAT enhancer binding protein (C/EBP), nuclear factor 1 (NF-1), nuclear factor Y (NF-Y), hepatocyte nuclear factor 4α (HNF4α) and sterol regulatory element (SRE), were identified in the promoter by site-directed mutation and functional assays. HNF4α and NF-1 were confirmed to interact with the core promoter of Δ4 Fad by gel shift assay and mass spectrometry. Moreover, over-expression of HNF4α increased promoter activity in HEK 293T cells and mRNA level of Δ4 Fad in rabbitfish primary hepatocytes, respectively. The results indicated that HNF4α is a TF of rabbitfish Δ4 Fad. To our knowledge, this is the first report on promoter structure of a Δ4 Fad, and also the first demonstration of HNF4α as a TF of vertebrate Fad gene involved in transcription regulation of LC-PUFA biosynthesis. PMID:27472219

Enigmatic Sedimentary Deposits Within Partially Exhumed Impact Craters in the Aeolis Dorsa Region, Mars: Evidence for Past Crater Lakes

NASA Astrophysics Data System (ADS)

Peel, S. E.; Burr, D. M.

2018-06-01

We mapped enigmatic sedimentary deposits within five partially exhumed impact craters within the Aeolis Dorsa Region of Mars. Ten units have been identified and are found to be consistent with deposition within and adjacent to lacustrine systems.

A study of the passive gait of a compass-like biped robot: Symmetry and chaos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goswami, A.; Espiau, B.; Thuilot, B.

1998-12-01

The focus of this work is a systematic study of the passive gait of a compass-like planar, biped robot on inclined slopes. The robot is kinematically equivalent to a double pendulum, possessing two kneeless legs with point masses and a third point mass at the hip joint. Three parameters, namely, the ground-slope angle and the normalized mass and length of the robot describe its gait. The authors show that in response to a continuous change in any one of its parameters, the symmetric and steady stable gait of the unpowered robot gradually evolves through a regime of bifurcations characterized bymore » progressively complicated asymmetric gaits, eventually arriving at an apparently chaotic gait where not two steps are identical. The robot can maintain this gait indefinitely. A necessary (but not sufficient) condition for the stability of such gaits is the contraction of the phase-fluid volume. For this frictionless robot, the volume contraction, which the authors compute, is caused by the dissipative effects of the ground-impact model. In the chaotic regime, the fractal dimension of the robot`s strange attractor (2.07) compared to its state-space dimension (4) also reveals strong contraction. The authors present a novel graphical technique based on the first return map that compactly captures the entire evolution of the gait, from symmetry to chaos. Additional passive dissipative elements in the robot joint results in a significant improvement in the stability and the versatility of the gait, and provide a rich repertoire for simple controls laws.« less

Actinous enigma or enigmatic actin

PubMed Central

Povarova, Olga I; Uversky, Vladimir N; Kuznetsova, Irina M; Turoverov, Konstantin K

2014-01-01

Being the most abundant protein of the eukaryotic cell, actin continues to keep its secrets for more than 60 years. Everything about this protein, its structure, functions, and folding, is mysteriously counterintuitive, and this review represents an attempt to solve some of the riddles and conundrums commonly found in the field of actin research. In fact, actin is a promiscuous binder with a wide spectrum of biological activities. It can exist in at least three structural forms, globular, fibrillar, and inactive (G-, F-, and I-actin, respectively). G-actin represents a thermodynamically instable, quasi-stationary state, which is formed in vivo as a result of the energy-intensive, complex posttranslational folding events controlled and driven by cellular folding machinery. The G-actin structure is dependent on the ATP and Mg2+ binding (which in vitro is typically substituted by Ca2+) and protein is easily converted to the I-actin by the removal of metal ions and by action of various denaturing agents (pH, temperature, and chemical denaturants). I-actin cannot be converted back to the G-form. Foldable and “natively folded” forms of actin are always involved in interactions either with the specific protein partners, such as Hsp70 chaperone, prefoldin, and the CCT chaperonin during the actin folding in vivo or with Mg2+ and ATP as it takes place in the G-form. We emphasize that the solutions for the mysteries of actin multifunctionality, multistructurality, and trapped unfolding can be found in the quasi-stationary nature of this enigmatic protein, which clearly possesses many features attributed to both globular and intrinsically disordered proteins. PMID:28232879

Questioning hagfish affinities of the enigmatic Devonian vertebrate Palaeospondylus

NASA Astrophysics Data System (ADS)

Johanson, Zerina; Smith, Moya; Sanchez, Sophie; Senden, Tim; Trinajstic, Kate; Pfaff, Cathrin

2017-07-01

Palaeospondylus gunni Traquair, 1890 is an enigmatic Devonian vertebrate whose taxonomic affinities have been debated since it was first described. Most recently, Palaeospondylus has been identified as a stem-group hagfish (Myxinoidea). However, one character questioning this assignment is the presence of three semicircular canals in the otic region of the cartilaginous skull, a feature of jawed vertebrates. Additionally, new tomographic data reveal that the following characters of crown-group gnathostomes (chondrichthyans + osteichthyans) are present in Palaeospondylus: a longer telencephalic region of the braincase, separation of otic and occipital regions by the otico-occipital fissure, and vertebral centra. As well, a precerebral fontanelle and postorbital articulation of the palatoquadrate are characteristic of certain chondrichthyans. Similarities in the structure of the postorbital process to taxa such as Pucapampella, and possible presence of the ventral cranial fissure, both support a resolution of Pa. gunni as a stem chondrichthyan. The internally mineralized cartilaginous skeleton in Palaeospondylus may represent a stage in the loss of bone characteristic of the Chondrichthyes.

The enigmatic fast leaflet rotation in Desmodium motorium: butterfly mimicry for defense?

PubMed

Lev-Yadun, Simcha

2013-06-01

I propose that the enigmatic leaflet movements in elliptical circles every few minutes of the Indian telegraph (semaphore) plant Desmodium motorium ( = D. gyrans = Hedysarum gyrans = Codariocalyx motorius), which has intrigued scientists for centuries, is a new type of butterfly or general winged arthropod mimicry by this plant. Such leaflet movement may deceive a passing butterfly searching for an un-occupied site suitable to deposit its eggs, that the plant is already occupied. It may also attract insectivorous birds, reptiles or arthropods to the plant because it looks as if it is harboring a potential prey and while they patrol there, they can find insects or other invertebrates that indeed attack the plant. The possibility that diurnal mammalian herbivores may also be deterred by these movements should not be dismissed.

An Enigmatic Death in Farm Chopping Machine: Is This the Perfect Murder?

PubMed

Gioia, Sara; Lancia, Massimo; Bacci, Mauro; Suadoni, Fabio

2015-09-01

Forensic autopsy, like the other sectors in medicine, has benefited from the technological progress and the creation of multidisciplinary teams to unveil more and more finely planned criminal intents.Forensic pathologists, however, can sometimes deal with very enigmatic cases, meeting so with the limits of their own knowledge. Therefore, in these cases, they must not allow themselves to be pressured by inquiring agencies, remaining instead always faithful to empiric observations.With regard to that, we present a peculiar case of death by shredding inside a grinding machinery. The magistrature consequently opened a dossier for willful murder. Lots of figures were appointed to solve the case and among them is the forensic pathologist. However, a great number of obstacles were put in the investigators' inquiries.Was it a perfect murder?

Optimization-based Dynamic Human Walking Prediction

DTIC Science & Technology

2007-01-01

9(1), 1997, p 10-17. 3. Chevallereau, C. and Aousin, Y. Optimal reference trajectories for walking and running of a biped robot. Robotica , v 19...28, 2001, Arlington, Virginia. 13. Mu, XP. and Wu, Q. Synthesis of a complete sagittal gait cycle for a five-link biped robot. Robotica , v 21...gait cycles of a biped robot. Robotica , v 21(2), 2003, p 199-210. 16. Sardain, P. and Bessonnet, G. Forces acting on a biped robot. Center of

Drip tectonics and the enigmatic uplift of the Central Anatolian Plateau.

PubMed

Göğüş, Oğuz H; Pysklywec, Russell N; Şengör, A M C; Gün, Erkan

2017-11-16

Lithospheric drips have been interpreted for various regions around the globe to account for the recycling of the continental lithosphere and rapid plateau uplift. However, the validity of such hypothesis is not well documented in the context of geological, geophysical and petrological observations that are tested against geodynamical models. Here we propose that the folding of the Central Anatolian (Kırşehir) arc led to thickening of the lithosphere and onset of "dripping" of the arc root. Our geodynamic model explains the seismic data showing missing lithosphere and a remnant structure characteristic of a dripping arc root, as well as enigmatic >1 km uplift over the entire plateau, Cappadocia and Galatia volcanism at the southern and northern plateau margins since ~10 Ma, respectively. Models show that arc root removal yields initial surface subsidence that inverts >1 km of uplift as the vertical loading and crustal deformation change during drip evolution.

The mythic species Issus analis Brullé, 1833 (Hemiptera, Fulgoroidea, Issidae): still an enigmatic taxon.

PubMed

Gnezdilov, Vladimir M; Bourgoin, Thierry

2017-01-04

One Issidae specimen stored in Paris museum historical collections is reported as holotype of Issus analis Brullé, 1833. From the original description, which is confirmed by study of this specimen, the species is moved to the genus Zopherisca Emeljanov, 2001 under a new combination Zopherisca analis (Brullé, 1833), comb. n. Date of description is discussed and modified from 1832 to 1833 accordingly. Unfortunately being a female as type specimen, the species remains quite enigmatic until some molecular analsysis could be undertaken on this old material.

A new enigmatic Late Miocene mylodontoid sloth from northern South America

PubMed Central

Rincón, Ascanio D.; McDonald, H. Gregory; Solórzano, Andrés; Flores, Mónica Núñez; Ruiz-Ramoni, Damián

2015-01-01

A new genus and species of sloth (Eionaletherium tanycnemius gen. et sp. nov.) recently collected from the Late Miocene Urumaco Formation, Venezuela (northern South America) is herein described based on a partial skeleton including associated femora and tibiae. In order to make a preliminary analysis of the phylogenetic affinities of this new sloth we performed a discriminate analysis based on several characters of the femur and tibia of selected Mylodontoidea and Megatherioidea sloths. The consensus tree produced indicates that the new sloth, E. tanycnemius, is a member of the Mylodontoidea. Surprisingly, the new taxon shows some enigmatic features among Neogene mylodontoid sloths, e.g. femur with a robust lesser trochanter that projects medially and the straight distinctly elongated tibia. The discovery of E. tanycnemius increases the diversity of sloths present in the Urumaco sequence to ten taxa. This taxon supports previous studies of the sloth assemblage from the Urumaco sequence as it further indicates that there are several sloth lineages present that are unknown from the better sampled areas of southern South America. PMID:26064594

First NICER Observations of the Enigmatic Be Star, Gamma Cassiopeiae

NASA Astrophysics Data System (ADS)

Hamaguchi, Kenji; Drake, Stephen; Corcoran, Michael; Gendreau, Keith C.; Steiner, Jack; NICER team

2018-01-01

Gamma Cassiopeiae is an enigmatic Be star with unusually hard, strong X-ray emission compared with normal main-sequence B stars (but a much lower X-ray luminosity than the classic X-ray binaries). The X-ray characteristics - hot (kT ~12 keV), thermal plasma spectrum and rapid time variations on timescales of 10-1000 sec - is reminiscent of accreting compact objects. Alternatively, its shot-like rapid variations somewhat resemble solar-type magnetic reconnection flares, so that plasma heating by the star-disk magnetic dynamo of the Be star has been proposed. A recent discovery of rapid X-ray color variations with the Suzaku X-ray observatory revealed the presence of rapidly moving absorbers in the X-ray line of sight, giving a strong constraint on the geometry of the X-ray emitting regions and absorbers.The X-ray observatory onboard ISS, NICER, has observed Gamma Cas multiple times. The large collecting area in the 0.3-10 keV band, tolerance to photon pile-ups, and decent energy resolution in particular below 1 keV, should provide excellent pieces of information on how the X-ray emission and/or absorbing column change on short timescales. We will present the first result of the gamma Cas observations made by the NICER observatory.

Long-term dynamics of freshwater red tide in shallow lake in central Japan.

PubMed

Hirabayashi, Kimio; Yoshizawa, Kazuya; Yoshida, Norihiko; Ariizumi, Kazunori; Kazama, Futaba

2007-01-01

The aim of this study is to clarify the long-term dynamics of the red tide occurring in Lake Kawaguchi. The measurement of environmental factors and water sampling were carried out monthly at a fixed station in Lake Kawaguchi's center basin from April 1993 to March 2004. On June 26, 1995, the horizontal distribution ofPeridinium bipes was investigated using a plastic pipe, obtaining 0∼1-m layers of water column samples at 68 locations across the entire lake. P. bipes showed an explosive growth and formed a freshwater red tide in the early summer of 1995, when the nutrient level was higher than those in the other years, particularly the phosphate concentration in the surface layer. The dissolved total phosphorus (DTP) concentration was sufficient forP. bipes growth in that year. In the study of its horizontal distribution,P. bipes was found at all the locations. The numbers of cells per milliliter ranged from 67 to 5360, averaging 1094±987 cells/ml, with particularly high densities along the northern shore. Since then,P. bipes has annually averaged about 25 cells/ml in Lake Kawaguchi. We observed that the red tide caused byP. bipes correlates with a high DTP concentration in Lake Kawaguchi.

Simulated Lidar Images of Human Pose using a 3DS Max Virtual Laboratory

DTIC Science & Technology

2015-12-01

developed in Autodesk 3DS Max, with an animated, biofidelic 3D human mesh biped character ( avatar ) as the subject. The biped animation modifies the digital...character ( avatar ) as the subject. The biped animation modifies the digital human model through a time sequence of motion capture data representing an...AFB. Mr. Isiah Davenport from Infoscitex Corp developed the method for creating the biofidelic avatars from laboratory data and 3DS Max code for

The cochlea of the enigmatic pygmy right whale Caperea marginata informs mysticete phylogeny.

PubMed

Park, Travis; Marx, Felix G; Fitzgerald, Erich M G; Evans, Alistair R

2017-06-01

The pygmy right whale, Caperea marginata, is the least understood extant baleen whale (Cetacea, Mysticeti). Knowledge on its basic anatomy, ecology, and fossil record is limited, even though its singular position outside both balaenids (right whales) and balaenopteroids (rorquals + grey whales) gives Caperea a pivotal role in mysticete evolution. Recent investigations of the cetacean cochlea have provided new insights into sensory capabilities and phylogeny. Here, we extend this advance to Caperea by describing, for the first time, the inner ear of this enigmatic species. The cochlea is large and appears to be sensitive to low-frequency sounds, but its hearing limit is relatively high. The presence of a well-developed tympanal recess links Caperea with cetotheriids and balaenopteroids, rather than balaenids, contrary to the traditional morphological view of a close Caperea-balaenid relationship. Nevertheless, a broader sample of the cetotheriid Herpetocetus demonstrates that the presence of a tympanal recess can be variable at the specific and possibly even the intraspecific level. © 2017 Wiley Periodicals, Inc.

On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia.

PubMed

Jörger, Katharina M; Stöger, Isabella; Kano, Yasunori; Fukuda, Hiroshi; Knebelsberger, Thomas; Schrödl, Michael

2010-10-25

A robust phylogenetic hypothesis of euthyneuran gastropods, as a basis to reconstructing their evolutionary history, is still hindered by several groups of aberrant, more or less worm-like slugs with unclear phylogenetic relationships. As a traditional "order" in the Opisthobranchia, the Acochlidia have a long history of controversial placements, among others influenced by convergent adaptation to the mainly meiofaunal habitats. The present study includes six out of seven acochlidian families in a comprehensive euthyneuran taxon sampling with special focus on minute, aberrant slugs. Since there is no fossil record of tiny, shell-less gastropods, a molecular clock was used to estimate divergence times within Euthyneura. Our multi-locus molecular study confirms Acochlidia in a pulmonate relationship, as sister to Eupulmonata. Previous hypotheses of opisthobranch relations, or of a common origin with other meiofaunal Euthyneura, are clearly rejected. The enigmatic amphibious and insectivorous Aitengidae incerta sedis clusters within Acochlidia, as sister to meiofaunal and brackish Pseudunelidae and limnic Acochlidiidae. Euthyneura, Opisthobranchia and Pulmonata as traditionally defined are non-monophyletic. A relaxed molecular clock approach indicates a late Palaeozoic diversification of Euthyneura and a Mesozoic origin of the major euthyneuran diversity, including Acochlidia. The present study shows that the inclusion of small, enigmatic groups is necessary to solve deep-level phylogenetic relationships, and underlines that "pulmonate" and "opisthobranch" phylogeny, respectively, cannot be solved independently from each other. Our phylogenetic hypothesis requires reinvestigation of the traditional classification of Euthyneura: morphological synapomorphies of the traditionally defined Pulmonata and Opisthobranchia are evaluated in light of the presented phylogeny, and a redefinition of major groups is proposed. It is demonstrated that the invasion of the meiofaunal

An enigmatic case presentation of Budd-Chiari syndrome with pulmonary embolism: An unusual syndrome with an uncommon complication.

PubMed

Al-Sharydah, A M; Al-Abdulwahhab, A H; Abu AlOla, H A

2018-05-03

In patients with a hypercoagulable state, such as patients with pulmonary embolism and/or Budd-Chiari syndrome, the complications from multiple gene mutations are more numerous than those from a single mutation. The authors present a woman with no major prior medical history who presented with pulmonary embolism and Budd-Chiari syndrome; this enigmatic co-occurrence has never been solely reported without underlying aetiology in a patient without prior medical conditions. A 20-year-old female presented to the emergency room complaining of a sudden onset of acute epigastric abdominal pain lasting for approximately 2 h. The patient's liver enzymes were severely elevated. Computed tomography of her abdomen showed thrombosed hepatic veins as well as supra-hepatic and hepatic portions of the inferior vena cava. She was becoming progressively hypotensive despite supplying intravenous fluid. Consequently, the patient received a contrast chest CT, which revealed the presence of acute pulmonary embolism; to confirm the diagnosis of a perfusion abnormality with normal ventilation, a clear radiograph in that region was obtained, denoting a V/Q study mismatch. Many details regarding the enigmatic mechanism behind the appearance of such a thrombotic co-occurrence in our patient are unclear. Since the anticardiolipin antibody IgG and IgM serum levels were normal, blood eosinophil count was persistently normal, and no signs of autoimmune disease were found, the diagnosis of autoimmune disease in the case under discussion is unlikely. Adding pulmonary embolism to the list of complications associated with Budd-Chiari syndrome is highly suggested, regardless of having predisposing condition(s). Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

A genome-wide perspective on the evolutionary history of enigmatic wolf-like canids

PubMed Central

vonHoldt, Bridgett M.; Pollinger, John P.; Earl, Dent A.; Knowles, James C.; Boyko, Adam R.; Parker, Heidi; Geffen, Eli; Pilot, Malgorzata; Jedrzejewski, Wlodzimierz; Jedrzejewska, Bogumila; Sidorovich, Vadim; Greco, Claudia; Randi, Ettore; Musiani, Marco; Kays, Roland; Bustamante, Carlos D.; Ostrander, Elaine A.; Novembre, John; Wayne, Robert K.

2011-01-01

High-throughput genotyping technologies developed for model species can potentially increase the resolution of demographic history and ancestry in wild relatives. We use a SNP genotyping microarray developed for the domestic dog to assay variation in over 48K loci in wolf-like species worldwide. Despite the high mobility of these large carnivores, we find distinct hierarchical population units within gray wolves and coyotes that correspond with geographic and ecologic differences among populations. Further, we test controversial theories about the ancestry of the Great Lakes wolf and red wolf using an analysis of haplotype blocks across all 38 canid autosomes. We find that these enigmatic canids are highly admixed varieties derived from gray wolves and coyotes, respectively. This divergent genomic history suggests that they do not have a shared recent ancestry as proposed by previous researchers. Interspecific hybridization, as well as the process of evolutionary divergence, may be responsible for the observed phenotypic distinction of both forms. Such admixture complicates decisions regarding endangered species restoration and protection. PMID:21566151

On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia

PubMed Central

2010-01-01

Background A robust phylogenetic hypothesis of euthyneuran gastropods, as a basis to reconstructing their evolutionary history, is still hindered by several groups of aberrant, more or less worm-like slugs with unclear phylogenetic relationships. As a traditional "order" in the Opisthobranchia, the Acochlidia have a long history of controversial placements, among others influenced by convergent adaptation to the mainly meiofaunal habitats. The present study includes six out of seven acochlidian families in a comprehensive euthyneuran taxon sampling with special focus on minute, aberrant slugs. Since there is no fossil record of tiny, shell-less gastropods, a molecular clock was used to estimate divergence times within Euthyneura. Results Our multi-locus molecular study confirms Acochlidia in a pulmonate relationship, as sister to Eupulmonata. Previous hypotheses of opisthobranch relations, or of a common origin with other meiofaunal Euthyneura, are clearly rejected. The enigmatic amphibious and insectivorous Aitengidae incerta sedis clusters within Acochlidia, as sister to meiofaunal and brackish Pseudunelidae and limnic Acochlidiidae. Euthyneura, Opisthobranchia and Pulmonata as traditionally defined are non-monophyletic. A relaxed molecular clock approach indicates a late Palaeozoic diversification of Euthyneura and a Mesozoic origin of the major euthyneuran diversity, including Acochlidia. Conclusions The present study shows that the inclusion of small, enigmatic groups is necessary to solve deep-level phylogenetic relationships, and underlines that "pulmonate" and "opisthobranch" phylogeny, respectively, cannot be solved independently from each other. Our phylogenetic hypothesis requires reinvestigation of the traditional classification of Euthyneura: morphological synapomorphies of the traditionally defined Pulmonata and Opisthobranchia are evaluated in light of the presented phylogeny, and a redefinition of major groups is proposed. It is demonstrated that

Walking on a moving surface: energy-optimal walking motions on a shaky bridge and a shaking treadmill can reduce energy costs below normal.

PubMed

Joshi, Varun; Srinivasan, Manoj

2015-02-08

Understanding how humans walk on a surface that can move might provide insights into, for instance, whether walking humans prioritize energy use or stability. Here, motivated by the famous human-driven oscillations observed in the London Millennium Bridge, we introduce a minimal mathematical model of a biped, walking on a platform (bridge or treadmill) capable of lateral movement. This biped model consists of a point-mass upper body with legs that can exert force and perform mechanical work on the upper body. Using numerical optimization, we obtain energy-optimal walking motions for this biped, deriving the periodic body and platform motions that minimize a simple metabolic energy cost. When the platform has an externally imposed sinusoidal displacement of appropriate frequency and amplitude, we predict that body motion entrained to platform motion consumes less energy than walking on a fixed surface. When the platform has finite inertia, a mass- spring-damper with similar parameters to the Millennium Bridge, we show that the optimal biped walking motion sustains a large lateral platform oscillation when sufficiently many people walk on the bridge. Here, the biped model reduces walking metabolic cost by storing and recovering energy from the platform, demonstrating energy benefits for two features observed for walking on the Millennium Bridge: crowd synchrony and large lateral oscillations.

All things rhabdoid and SMARC: An enigmatic exploration with Dr. Louis P. Dehner.

PubMed

Fuller, Christine E

2016-11-01

Over the past several decades, our understanding of malignant rhabdoid tumors (MRT) and the central nervous system equivalent atypical teratoid/rhabdoid tumor (ATRT) has undergone considerable refinement, particularly in terms of genetic characterization. MRT (both renal and extra-renal) and ATRT share phenotypic similarities and a common genetic signature, that being inactivating alterations of the SWI/SNF complex component SMARCB1 (or rarely SMARCA4). Unfortunately, a wide array of tumors bears significantly overlapping phenotypic characteristics to MRT/ATRT, posing a formidable diagnostic challenge. Likewise, the list of tumors bearing SMARC-related alterations has grown at a dizzying pace, and the original assumption that SMARCB1 alterations were unique to MRT/ATRT has been essentially negated. It should come as no surprise that Dr. Louis P. Dehner, no stranger to enigmatic lesions, participated significantly in this pathologic controversy, and the circuitous journey of entity discovery and clarification. This review aims to (1) summarize our current knowledge of MRT and ATRT with an emphasis on genetic characterization, (2) present insight into so-called "composite rhabdoid tumors" (CRTs), and (3) and provide an updated account of others tumors bearing SMARC alterations. Copyright © 2016 Elsevier Inc. All rights reserved.

Functionally Enigmatic Genes: A Case Study of the Brain Ignorome

PubMed Central

Pandey, Ashutosh K.; Lu, Lu; Wang, Xusheng; Homayouni, Ramin; Williams, Robert W.

2014-01-01

What proportion of genes with intense and selective expression in specific tissues, cells, or systems are still almost completely uncharacterized with respect to biological function? In what ways do these functionally enigmatic genes differ from well-studied genes? To address these two questions, we devised a computational approach that defines so-called ignoromes. As proof of principle, we extracted and analyzed a large subset of genes with intense and selective expression in brain. We find that publications associated with this set are highly skewed—the top 5% of genes absorb 70% of the relevant literature. In contrast, approximately 20% of genes have essentially no neuroscience literature. Analysis of the ignorome over the past decade demonstrates that it is stubbornly persistent, and the rapid expansion of the neuroscience literature has not had the expected effect on numbers of these genes. Surprisingly, ignorome genes do not differ from well-studied genes in terms of connectivity in coexpression networks. Nor do they differ with respect to numbers of orthologs, paralogs, or protein domains. The major distinguishing characteristic between these sets of genes is date of discovery, early discovery being associated with greater research momentum—a genomic bandwagon effect. Finally we ask to what extent massive genomic, imaging, and phenotype data sets can be used to provide high-throughput functional annotation for an entire ignorome. In a majority of cases we have been able to extract and add significant information for these neglected genes. In several cases—ELMOD1, TMEM88B, and DZANK1—we have exploited sequence polymorphisms, large phenome data sets, and reverse genetic methods to evaluate the function of ignorome genes. PMID:24523945

Functionally enigmatic genes: a case study of the brain ignorome.

PubMed

Pandey, Ashutosh K; Lu, Lu; Wang, Xusheng; Homayouni, Ramin; Williams, Robert W

2014-01-01

What proportion of genes with intense and selective expression in specific tissues, cells, or systems are still almost completely uncharacterized with respect to biological function? In what ways do these functionally enigmatic genes differ from well-studied genes? To address these two questions, we devised a computational approach that defines so-called ignoromes. As proof of principle, we extracted and analyzed a large subset of genes with intense and selective expression in brain. We find that publications associated with this set are highly skewed--the top 5% of genes absorb 70% of the relevant literature. In contrast, approximately 20% of genes have essentially no neuroscience literature. Analysis of the ignorome over the past decade demonstrates that it is stubbornly persistent, and the rapid expansion of the neuroscience literature has not had the expected effect on numbers of these genes. Surprisingly, ignorome genes do not differ from well-studied genes in terms of connectivity in coexpression networks. Nor do they differ with respect to numbers of orthologs, paralogs, or protein domains. The major distinguishing characteristic between these sets of genes is date of discovery, early discovery being associated with greater research momentum--a genomic bandwagon effect. Finally we ask to what extent massive genomic, imaging, and phenotype data sets can be used to provide high-throughput functional annotation for an entire ignorome. In a majority of cases we have been able to extract and add significant information for these neglected genes. In several cases--ELMOD1, TMEM88B, and DZANK1--we have exploited sequence polymorphisms, large phenome data sets, and reverse genetic methods to evaluate the function of ignorome genes.

Walking on a moving surface: energy-optimal walking motions on a shaky bridge and a shaking treadmill can reduce energy costs below normal

PubMed Central

Joshi, Varun; Srinivasan, Manoj

2015-01-01

Understanding how humans walk on a surface that can move might provide insights into, for instance, whether walking humans prioritize energy use or stability. Here, motivated by the famous human-driven oscillations observed in the London Millennium Bridge, we introduce a minimal mathematical model of a biped, walking on a platform (bridge or treadmill) capable of lateral movement. This biped model consists of a point-mass upper body with legs that can exert force and perform mechanical work on the upper body. Using numerical optimization, we obtain energy-optimal walking motions for this biped, deriving the periodic body and platform motions that minimize a simple metabolic energy cost. When the platform has an externally imposed sinusoidal displacement of appropriate frequency and amplitude, we predict that body motion entrained to platform motion consumes less energy than walking on a fixed surface. When the platform has finite inertia, a mass- spring-damper with similar parameters to the Millennium Bridge, we show that the optimal biped walking motion sustains a large lateral platform oscillation when sufficiently many people walk on the bridge. Here, the biped model reduces walking metabolic cost by storing and recovering energy from the platform, demonstrating energy benefits for two features observed for walking on the Millennium Bridge: crowd synchrony and large lateral oscillations. PMID:25663810

Mars, the funny history of canals.1-the enigmatic planet. the plurality of worlds; Mars, la folle histoire des canaux. 1-l'énigmatique planète. la pluralité des mondes

NASA Astrophysics Data System (ADS)

Raffaitin, Gérard; Durand, Pierre

2016-03-01

Since the 17th century, the study of the planet Mars interested astronomers. The changes observed on Mars were enigmatic. Several philosophers thought that this planet does have inhabitants. Giovanni Schiaparelli observed canals and their changes. Was it the sign of a life on this planet?

Hnf4α is involved in the regulation of vertebrate LC-PUFA biosynthesis: insights into the regulatory role of Hnf4α on expression of liver fatty acyl desaturases in the marine teleost Siganus canaliculatus.

PubMed

Wang, Shuqi; Chen, Junliang; Jiang, Danli; Zhang, Qinghao; You, Cuihong; Tocher, Douglas R; Monroig, Óscar; Dong, Yewei; Li, Yuanyou

2018-06-01

Long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis is an important metabolic pathway in vertebrates, especially fish, considering they are the major source of n-3 LC-PUFA in the human diet. However, most fish have only limited capability for biosynthesis of LC-PUFA. The rabbitfish (Siganus canaliculatus) is able to synthesize LC-PUFA as it has all the key enzyme activities required including Δ6Δ5 Fads2, Δ4 Fads2, Elovl5, and Elovl4. We previously reported a direct interaction between the transcription factor Hnf4α and the promoter regions of Δ4 and Δ6Δ5 Fads2, which suggested that Hnf4α was involved in the transcriptional regulation of fads2 in rabbitfish. For functionally investigating it further, a full-length cDNA of 1736-bp-encoding rabbitfish Hnf4α with 454 amino acids was cloned, which was highly expressed in intestine, followed by liver and eyes. Similar to the expression characteristics of its target genes Δ4 and Δ6Δ5 fads2, levels of hnf4α mRNA in liver and eyes were higher in fish reared at low salinity than those reared in high salinity. After the rabbitfish primary hepatocytes were, respectively, incubated with alverine, benfluorex or BI6015, which were anticipated agonists or antagonist for Hnf4α, the mRNA level of Δ6Δ5 and Δ4 fads2 displayed a similar change tendency with that of hnf4α mRNA. Furthermore, when the mRNA level of hhf4α was knocked down using siRNA, the expression of Δ6Δ5 and Δ4 fads2 also decreased. Together, these data suggest that Hnf4α is involved in the transcriptional regulation of LC-PUFA biosynthesis, specifically, by targeting Δ4 and Δ6Δ5 fads2 in rabbitfish.

The Enigmatic Alphavirus Non-Structural Protein 3 (nsP3) Revealing Its Secrets at Last

PubMed Central

Götte, Benjamin; Liu, Lifeng

2018-01-01

Alphaviruses encode 4 non-structural proteins (nsPs), most of which have well-understood functions in capping and membrane association (nsP1), polyprotein processing and RNA helicase activity (nsP2) and as RNA-dependent RNA polymerase (nsP4). The function of nsP3 has been more difficult to pin down and it has long been referred to as the more enigmatic of the nsPs. The protein comprises three domains, an N-terminal macro domain, a central zinc-binding domain and a C-terminal hypervariable domain (HVD). In this article, we review old and new literature about the functions of the three domains. Much progress in recent years has contributed to a picture of nsP3, particularly through its HVD as a hub for interactions with host cell molecules, with multiple effects on the biology of the host cell at early points in infection. These and many future discoveries will provide targets for anti-viral therapies as well as strategies for modification of vectors for vaccine and oncolytic interventions. PMID:29495654

Resistant tissues of modern marchantioid liverworts resemble enigmatic Early Paleozoic microfossils

PubMed Central

Graham, Linda E.; Wilcox, Lee W.; Cook, Martha E.; Gensel, Patricia G.

2004-01-01

Absence of a substantial pretracheophyte fossil record for bryophytes (otherwise predicted by molecular systematics) poses a major problem in our understanding of earliest land-plant structure. In contrast, there exist enigmatic Cambrian–Devonian microfossils (aggregations of tubes or sheets of cells or possibly a combination of both) controversially interpreted as an extinct group of early land plants known as nematophytes. We used an innovative approach to explore these issues: comparison of tube and cell-sheet microfossils with experimentally degraded modern liverworts as analogues of ancient early land plants. Lower epidermal surface tissues, including rhizoids, of Marchantia polymorpha and Conocephalum conicum were resistant to breakdown after rotting for extended periods or high-temperature acid treatment (acetolysis), suggesting fossilization potential. Cell-sheet and rhizoid remains occurred separately or together depending on the degree of body degradation. Rhizoid break-off at the lower epidermal surface left rimmed pores at the centers of cell rosettes; these were similar in structure, diameter, and distribution to pores characterizing nematophyte cell-sheet microfossils known as Cosmochlaina. The range of Marchantia rhizoid diameters overlapped that of Cosmochlaina pores. Approximately 14% of dry biomass of Marchantia vegetative thalli and 40% of gametangiophores was resistant to acetolysis. Pre- and posttreatment cell-wall autofluorescence suggested the presence of phenolic compounds that likely protect lower epidermal tissues from soil microbe attack and provide dimensional stability to gametangiophores. Our results suggest that at least some microfossils identified as nematophytes may be the remains of early marchantioid liverworts similar in some ways to modern Marchantia and Conocephalum. PMID:15263095

Review of the enigmatic Eocene shark genus Xiphodolamia (Chondrichthyes, Lamniformes) and description of a new species recovered from Angola, Iran and Jordan

NASA Astrophysics Data System (ADS)

Adnet, S.; Hosseinzadeh, R.; Antunes, M. T.; Balbino, A. C.; Kozlov, V. A.; Cappetta, H.

2009-10-01

Little is known about the extinct Xiphodolamia, a peculiar lamnid shark which inhabited the Eocene seas. The reexamination of a large set of fossilized teeth specimens from the Ypresian of Kazakhstan has enabled the reconstitution of the tooth series of this enigmatic taxa of lamnid shark. Five distinct tooth morphologies seem to occur in X. ensis Leidy [Leidy, J., 1877. Description of vertebrate remains, chiefly from the phosphate beds of South Carolina. Journal of the Academy of Natural Sciences of Philadelphia 8, 209-261] species revealing a weak ontogenetic variation. Such specific variation in tooth shape means that the other described species may be their junior synonyms. Dental morphology perfectly conforms with a Lamniforme but does not prove the current attribution to the Lamnidae family due to some inconsistent dental features observed, such as the presence of symphysial teeth. This genus could be regarded as an old lineage branched from the stem group of Lamnidae, close to the Isuroids sharks. Several Xiphodolamia teeth, originating both from old collections and new acquisitions, are reported and illustrated in order to provide information about a new species described here: Xiphodolamia serrata nov. sp. This species, currently limited to deposits in Angola, Jordan and Iran and dated at the Late Eocene, is easily distinguishable from the Early-Middle Eocene material belonging to the genus by the presence of serrated cutting edges. Adding to the type species considered here as the only valid taxa during the Early-Middle Eocene period, the temporal range of this genus extends to the Late Eocene, thus setting its upper stratigraphic limit prior to its disappearance as enigmatic as its appearance in the Early Eocene was.

The Origin of X-ray Emission from the Enigmatic Be Star γ Cassiopeiae

NASA Astrophysics Data System (ADS)

Hamaguchi, K.; Oskinova, L.; Russell, C. M. P.; Petre, R.; Enoto, T.; Morihana, K.; Ishida, M.

2017-11-01

Gamma Cassiopeiae is an enigmatic Be star with unusually hard, strong X-ray emission compared with normal main-sequence B stars. The origin has been debated for decades between two theories: mass accretion onto a hidden compact companion and a magnetic dynamo driven by the star-Be disk differential rotation. There has been no decisive signature found that supports either theory, such as a pulse in X-ray emission or the presence of large-scale magnetic field. In a ~100 ksec duration observation of the star with the Suzaku X-ray observatory in 2011, we detected six rapid X-ray spectral hardening events called ``softness dips''. All the softness dip events show symmetric softness ratio variations, and some of them have flat bottoms apparently due to saturation. The softness dip spectra are best described by either ~40% or ~70% partial covering absorption to kT ~12 keV plasma emission by matter with a neutral hydrogen column density of ~2 - 8 × 1021cm-2, while the spectrum outside of these dips is almost free of absorption. This result suggests that two distinct X-ray emitting spots in the γ Cas system, perhaps on a white dwarf companion with dipole mass accretion, are occulted by blobs in the Be stellar wind, the Be disk, or rotating around the white dwarf companion. The formation of a Be star and white dwarf binary system requires mass transfer between two stars; γ Cas may have experienced such activity in the past.

Small, Enigmatic Plasmids of the Nosocomial Pathogen, Acinetobacter baumannii: Good, Bad, Who Knows?

PubMed Central

Lean, Soo Sum; Yeo, Chew Chieng

2017-01-01

Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has become a serious healthcare concern within a span of two decades due to its ability to rapidly acquire resistance to all classes of antimicrobial compounds. One of the key features of the A. baumannii genome is an open pan genome with a plethora of plasmids, transposons, integrons, and genomic islands, all of which play important roles in the evolution and success of this clinical pathogen, particularly in the acquisition of multidrug resistance determinants. An interesting genetic feature seen in majority of A. baumannii genomes analyzed is the presence of small plasmids that usually ranged from 2 to 10 kb in size, some of which harbor antibiotic resistance genes and homologs of plasmid mobilization genes. These plasmids are often overlooked when compared to their larger, conjugative counterparts that harbor multiple antibiotic resistance genes and transposable elements. In this mini-review, we will examine our current knowledge of these small A. baumannii plasmids and look into their genetic diversity and phylogenetic relationships. Some of these plasmids, such as the Rep-3 superfamily group and the pRAY-type, which has no recognizable replicase genes, are quite widespread among diverse A. baumannii clinical isolates worldwide, hinting at their usefulness to the lifestyle of this pathogen. Other small plasmids especially those from the Rep-1 superfamily are truly enigmatic, encoding only hypothetical proteins of unknown function, leading to the question of whether these small plasmids are “good” or “bad” to their host A. baumannii. PMID:28861061

New remains of the enigmatic cetartiodactyl Bugtitherium grandincisivum Pilgrim, 1908, from the upper Oligocene of the Bugti Hills (Balochistan, Pakistan).

PubMed

Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, Syed Rafiqul Hassan; Benammi, Mouloud; Crochet, Jean-Yves; de Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

2006-07-01

Newly discovered fossil material of the enigmatic cetartiodactyl Bugtitherium grandincisivum from the upper Oligocene of the Bugti Member of the Chitarwata Formation in the Bugti Hills (Balochistan, Pakistan) is reported. These new specimens consist of two fragmentary muzzles (one preserving the first incisors and belonging to a juvenile) and a fragmentary right mandible with m3. The morphologies of the anterior dentition and m3 provided by these new specimens confirm the validity of the genus Bugtitherium and advocate probable anthracotheriid affinity for the genus rather than entelodontid or suoid affinities, but do not definitively close the debate about Bugtitherium's familial affinities within Cetartiodactyla. Although still poorly documented, this large-sized anthracotheriid-like cetartiodactyl is a possible key form for understanding the early evolution of hippos, and, in turn, the ancestry of whales, because of both its morphological similarities with hippos and primitive Paleogene whales and its Tethysian distribution.

New remains of the enigmatic cetartiodactyl Bugtitherium grandincisivum Pilgrim, 1908, from the upper Oligocene of the Bugti Hills (Balochistan, Pakistan)

NASA Astrophysics Data System (ADS)

Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, Syed Rafiqul Hassan; Benammi, Mouloud; Crochet, Jean-Yves; de Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

2006-07-01

Newly discovered fossil material of the enigmatic cetartiodactyl Bugtitherium grandincisivum from the upper Oligocene of the Bugti Member of the Chitarwata Formation in the Bugti Hills (Balochistan, Pakistan) is reported. These new specimens consist of two fragmentary muzzles (one preserving the first incisors and belonging to a juvenile) and a fragmentary right mandible with m3. The morphologies of the anterior dentition and m3 provided by these new specimens confirm the validity of the genus Bugtitherium and advocate probable anthracotheriid affinity for the genus rather than entelodontid or suoid affinities, but do not definitively close the debate about Bugtitherium’s familial affinities within Cetartiodactyla. Although still poorly documented, this large-sized anthracotheriid-like cetartiodactyl is a possible key form for understanding the early evolution of hippos, and, in turn, the ancestry of whales, because of both its morphological similarities with hippos and primitive Paleogene whales and its Tethysian distribution.

Phylogenetic analyses of complete mitochondrial genome sequences suggest a basal divergence of the enigmatic rodent Anomalurus

PubMed Central

Horner, David S; Lefkimmiatis, Konstantinos; Reyes, Aurelio; Gissi, Carmela; Saccone, Cecilia; Pesole, Graziano

2007-01-01

Background Phylogenetic relationships between Lagomorpha, Rodentia and Primates and their allies (Euarchontoglires) have long been debated. While it is now generally agreed that Rodentia constitutes a monophyletic sister-group of Lagomorpha and that this clade (Glires) is sister to Primates and Dermoptera, higher-level relationships within Rodentia remain contentious. Results We have sequenced and performed extensive evolutionary analyses on the mitochondrial genome of the scaly-tailed flying squirrel Anomalurus sp., an enigmatic rodent whose phylogenetic affinities have been obscure and extensively debated. Our phylogenetic analyses of the coding regions of available complete mitochondrial genome sequences from Euarchontoglires suggest that Anomalurus is a sister taxon to the Hystricognathi, and that this clade represents the most basal divergence among sampled Rodentia. Bayesian dating methods incorporating a relaxed molecular clock provide divergence-time estimates which are consistently in agreement with the fossil record and which indicate a rapid radiation within Glires around 60 million years ago. Conclusion Taken together, the data presented provide a working hypothesis as to the phylogenetic placement of Anomalurus, underline the utility of mitochondrial sequences in the resolution of even relatively deep divergences and go some way to explaining the difficulty of conclusively resolving higher-level relationships within Glires with available data and methodologies. PMID:17288612

Enigmatic organosiliceous rocks in the 2000 Ma petrified oil field in Russian Fennoscandia

NASA Astrophysics Data System (ADS)

Deines, Yu.; Melezhik, V.; Lepland, A.; Filippov, M.; Romashkin, A.; Rychanchik, D.

2009-04-01

The c. 2000 Ma, 900 m-thick, Zaonezhskaja Formation in the Onega basin, Russian Fennoscandia, contains one of the greatest accumulations of organic matter (OM) in the Early Precambrian. It also represents a unique preservation of a supergiant petrified oil field. Zaonezhskaja Formation rocks are greenschist-facies volcaniclastic greywackes (distal turbidites), dolostone and limestones, mafic tuffs and lavas intruded by numerous mafic sills. Several sedimentary beds are enriched in OM with the overall content of total organic carbon (TOC) ranging from 0.1 to 16 wt.% whereas d13C varies between -44 and -17 per mil(V-PDB). The formation contains plentiful evidence of generation and migration of oil (now petrified) as well as oil traps. Results of geophysical surveys combined with drillcore data, including results recently obtained within the framework of the Fennoscandian Arctic Russia - Drilling Early Earth Project (FAR-DEEP), revealed numerous bodies of organosiliceous rocks (OSR) containing mainly silica (c. 57 wt.% SiO2), organic carbon (up to 40 wt.%), Al2O3 (c. 5 wt.%), S (c. 2 wt.%), and minor K, Mg, Fe, Ca and Ti. d13C of the OSR ranges between -40 and -20 per mil. The OSR form crudely stratified beds, cupola-like bodies or veins. The cupola-like bodies show cross-cutting (intrusive) contacts with the host turbiditic greywackes, reach thicknesses of 120 m with a lateral extent of several hundreds of metres. Veins are a few tens of centimetres thick. The OSR show close spatial association with gabbro sills. Although different fabrics have been recognised in the OSR, syngenetic macro- and microbreccias per se are the most common rock types. Fragments of different sedimentary rocks, as well as those with alternating C-rich and C-poor concentric lamina are present. The latter suggests precipitation from hydrothermal fluids. The nature of the OSR remains enigmatic. Several models have been advanced for explanation of origin of the OSR. However, neither of them

Incorporation of perception-based information in robot learning using fuzzy reinforcement learning agents

NASA Astrophysics Data System (ADS)

Zhou, Changjiu; Meng, Qingchun; Guo, Zhongwen; Qu, Wiefen; Yin, Bo

2002-04-01

Robot learning in unstructured environments has been proved to be an extremely challenging problem, mainly because of many uncertainties always present in the real world. Human beings, on the other hand, seem to cope very well with uncertain and unpredictable environments, often relying on perception-based information. Furthermore, humans beings can also utilize perceptions to guide their learning on those parts of the perception-action space that are actually relevant to the task. Therefore, we conduct a research aimed at improving robot learning through the incorporation of both perception-based and measurement-based information. For this reason, a fuzzy reinforcement learning (FRL) agent is proposed in this paper. Based on a neural-fuzzy architecture, different kinds of information can be incorporated into the FRL agent to initialise its action network, critic network and evaluation feedback module so as to accelerate its learning. By making use of the global optimisation capability of GAs (genetic algorithms), a GA-based FRL (GAFRL) agent is presented to solve the local minima problem in traditional actor-critic reinforcement learning. On the other hand, with the prediction capability of the critic network, GAs can perform a more effective global search. Different GAFRL agents are constructed and verified by using the simulation model of a physical biped robot. The simulation analysis shows that the biped learning rate for dynamic balance can be improved by incorporating perception-based information on biped balancing and walking evaluation. The biped robot can find its application in ocean exploration, detection or sea rescue activity, as well as military maritime activity.

RADIATIVE TRANSFER MODELING OF THE ENIGMATIC SCATTERING POLARIZATION IN THE SOLAR Na i D{sub 1} LINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belluzzi, Luca; Bueno, Javier Trujillo; Degl’Innocenti, Egidio Landi

2015-12-01

The modeling of the peculiar scattering polarization signals observed in some diagnostically important solar resonance lines requires the consideration of the detailed spectral structure of the incident radiation field as well as the possibility of ground level polarization, along with the atom's hyperfine structure and quantum interference between hyperfine F-levels pertaining either to the same fine structure J-level, or to different J-levels of the same term. Here we present a theoretical and numerical approach suitable for solving this complex non-LTE radiative transfer problem. This approach is based on the density-matrix metalevel theory (where each level is viewed as a continuousmore » distribution of sublevels) and on accurate formal solvers of the transfer equations and efficient iterative methods. We show an application to the D-lines of Na i, with emphasis on the enigmatic D{sub 1} line, pointing out the observable signatures of the various physical mechanisms considered. We demonstrate that the linear polarization observed in the core of the D{sub 1} line may be explained by the effect that one gets when the detailed spectral structure of the anisotropic radiation responsible for the optical pumping is taken into account. This physical ingredient is capable of introducing significant scattering polarization in the core of the Na i D{sub 1} line without the need for ground-level polarization.« less

Reinvestigating an enigmatic Late Cretaceous monocot: morphology, taxonomy, and biogeography of Viracarpon

PubMed Central

Manchester, Steven R.; Ramteke, Deepak; Villarraga-Gómez, Herminso

2018-01-01

was widespread and may be present in other Late Cretaceous assemblages. Viracarpon exhibits character combinations not present in any extant taxa and its affinities remain unresolved, possibly representing an extinct member of Alismatales. The character mosaic observed in Viracarpon and the broad distribution of the genus provide new data relevant to understanding early monocot evolution and suggest that the (thus far) largely invisible Late Cretaceous monocot diversification was characterized by enigmatic and/or stem taxa. PMID:29637023

Divergent mating patterns and a unique mode of external sperm transfer in Zoraptera: an enigmatic group of pterygote insects

NASA Astrophysics Data System (ADS)

Dallai, R.; Gottardo, M.; Mercati, D.; Machida, R.; Mashimo, Y.; Matsumura, Y.; Beutel, R. G.

2013-06-01

A remarkable external sperm transfer is described for the first time in a species of a group of winged insects (Pterygota), the enigmatic Zoraptera. Mating and sperm transfer of two species of the order were examined in detail, documented, and compared with each other and with patterns described for other species belonging to the order. The behavior differs strikingly in Zorotypus impolitus and Zorotypus magnicaudelli. A copula is performed by males and females of the latter, as it is also the case in other zorapteran species and generally in pterygote insects. In striking contrast to this, males of Z. impolitus do not copulate but deposit small (100 μm in diameter) spermatophores externally on the abdomen of the female. Each spermatophore contains only one giant spermatozoon (3 mm long and 3 μm wide), a unique feature in the entire Hexapoda. External sperm transfer in Pterygota is a highly unusual case of evolutionary reversal. The very small relict group Zoraptera displays a uniform general morphology but exhibits very different reproductive structures and patterns of mating behavior. This may be an extreme form of a more general situation in insects, with a specific form of selection resulting in an accelerated rate of evolution in the reproductive system.

Imaging 50,000 Oriented Ovoid Depressions Using LiDAR Elevation Data Elucidates the Enigmatic Character of The Carolina Bays: Wind & Wave, Or Cosmic Impact Detritus?

NASA Astrophysics Data System (ADS)

Davias, M. E.; Harris, T. H. S.

2017-12-01

80 years after aerial photography revealed thousands of aligned oval depressions on the USA's Atlantic Coastal Plain, the geomorphology of the "Carolina bays" remains enigmatic. Geologists and astronomers alike hold that invoking a cosmic impact for their genesis is indefensible. Rather, the bays are commonly attributed to gradualistic fluvial, marine and/or aeolian processes operating during the Pleistocene era. The major axis orientations of Carolina bays are noted for varying statistically by latitude, suggesting that, should there be any merit to a cosmic hypothesis, a highly accurate triangulation network and suborbital analysis would yield a locus and allow for identification of a putative impact site. Digital elevation maps using LiDAR technology offer the precision necessary to measure their exquisitely-carved circumferential rims and orientations reliably. To support a comprehensive geospatial survey of Carolina bay landforms (Survey) we generated about a million km2 of false-color hsv-shaded bare-earth topographic maps as KML-JPEG tile sets for visualization on virtual globes. Considering the evidence contained in the Survey, we maintain that interdisciplinary research into a possible cosmic origin should be encouraged. Consensus opinion does hold a cosmic impact accountable for an enigmatic Pleistocene event - the Australasian tektite strewn field - despite the failure of a 60-year search to locate the causal astroblem. Ironically, a cosmic link to the Carolina bays is considered soundly falsified by the identical lack of a causal impact structure. Our conjecture suggests both these events are coeval with a cosmic impact into the Great Lakes area during the Mid-Pleistocene Transition, at 786 ka ± 5 k. All Survey data and imagery produced for the Survey are available on the Internet to support independent research. A table of metrics for 50,000 bays examined for the Survey is available from an on-line Google Fusion Table: https://goo.gl/XTHKC4 . Each bay

Elucidation of the enigmatic IgD class-switch recombination via germline deletion of the IgH 3′ regulatory region

PubMed Central

Rouaud, Pauline; Saintamand, Alexis; Saad, Faten; Carrion, Claire; Lecardeur, Sandrine; Cogné, Michel

2014-01-01

Classical class-switch recombination (cCSR) substitutes the Cμ gene with Cγ, Cε, or Cα, thereby generating IgG, IgE, or IgA classes, respectively. This activation-induced deaminase (AID)–driven process is controlled by the IgH 3′ regulatory region (3′RR). Regulation of rare IgD CSR events has been enigmatic. We show that μδCSR occurs in mouse mesenteric lymph node (MLN) B cells and is AID-dependent. AID attacks differ from those in cCSR because they are not accompanied by extensive somatic hypermutation (SHM) of targeted regions and because repaired junctions exhibit features of the alternative end-joining (A-EJ) pathway. In contrast to cCSR and SHM, μδCSR is 3′RR-independent, as its absence affects neither breakpoint locations in Sμ- and Sδ-like (σδ) nor mutation patterns at Sμ-σδ junctions. Although mutations occur in the immediate proximity of the μδ junctions, SHM is absent distal to the junctions within both Sμ and rearranged VDJ regions. In conclusion, μδCSR is active in MLNs, occurs independently of 3′RR-driven assembly, and is even dramatically increased in 3′RR-deficient mice, further showing that its regulation differs from cCSR. PMID:24752300

Dynamic legged locomotion in robots and animals

NASA Astrophysics Data System (ADS)

Raibert, Marc; Playter, Robert; Ringrose, Robert; Bailey, Dave; Leeser, Karl

1995-01-01

This report documents our study of active legged systems that balance actively and move dynamically. The purpose of this research is to build a foundation of knowledge that can lead both to the construction of useful legged vehicles and to a better understanding of how animal locomotion works. In this report we provide an update on progress during the past year. Here are the topics covered in this report: (1) Is cockroach locomotion dynamic? To address this question we created three models of cockroaches, each abstracted at a different level. We provided each model with a control system and computer simulation. One set of results suggests that 'Groucho Running,' a type of dynamic walking, seems feasible at cockroach scale. (2) How do bipeds shift weight between the legs? We built a simple planar biped robot specifically to explore this question. It shifts its weight from one curved foot to the other, using a toe-off and toe-on strategy, in conjunction with dynamic tipping. (3) 3D biped gymnastics: The 3D biped robot has done front somersaults in the laboratory. The robot changes its leg length in flight to control rotation rate. This in turn provides a mechanism for controlling the landing attitude of the robot once airborne. (4) Passively stabilized layout somersault: We have found that the passive structure of a gymnast, the configuration of masses and compliances, can stabilize inherently unstable maneuvers. This means that body biomechanics could play a larger role in controlling behavior than is generally thought. We used a physical 'doll' model and computer simulation to illustrate the point. (5) Twisting: Some gymnastic maneuvers require twisting. We are studying how to couple the biomechanics of the system to its control to produce efficient, stable twisting maneuvers.

The last fossil primate in North America, new material of the enigmatic Ekgmowechashala from the Arikareean of Oregon.

PubMed

Samuels, Joshua X; Albright, L Barry; Fremd, Theodore J

2015-09-01

Primates were common in North America through most of the Eocene, but vanished in the Chadronian, about 35 million years ago. In the Arikareean, about 6 million years later, the enigmatic primate Ekgmowechashala appeared in the Great Plains and Oregon. This taxon shows little resemblance to other North American primates and its phylogenetic position has long been debated. New material of this taxon allows a revised assessment of its age and how it is related to other primates. Recently collected Ekgmowechashala specimens from the Turtle Cove Member of the John Day Formation in Oregon are described. These specimens are compared to previously collected material from South Dakota and Nebraska, as well as other fossil primates from North America and Asia. Study of the John Day material allows diagnosis of a new, distinct species. Comparison of Ekgmowechashala to a pair of recently described Asian primates, Muangthanhinius and Bugtilemur, suggests that it is a strepsirrhine adapiform, rather than an omomyid. The well-defined stratigraphy and dated marker beds of the Turtle Cove Member provide a refined age for Ekgmowechashala occurrences in Oregon, during the Oligocene (early Arikareean). The age and morphology of these ekgmowechashaline taxa suggest that the group originated in Asia and dispersed to North America in the Oligocene, after the extinction of other primates in North America. Contemporaneous occurrences of Ekgmowechashala in Oregon and the Great Plains indicate the last non-human primates vanished in North America about 26 million years ago. © 2015 Wiley Periodicals, Inc.

Anatomy of the Enigmatic Reptile Elachistosuchus huenei Janensch, 1949 (Reptilia: Diapsida) from the Upper Triassic of Germany and Its Relevance for the Origin of Sauria.

PubMed

Sobral, Gabriela; Sues, Hans-Dieter; Müller, Johannes

2015-01-01

The holotype and only known specimen of the enigmatic small reptile Elachistosuchus huenei Janensch, 1949 from the Upper Triassic (Norian) Arnstadt Formation of Saxony-Anhalt (Germany) is redescribed using μCT scans of the material. This re-examination revealed new information on the morphology of this taxon, including previously unknown parts of the skeleton such as the palate, braincase, and shoulder girdle. Elachistosuchus is diagnosed especially by the presence of the posterolateral process of the frontal, the extension of the maxillary tooth row to the posterior margin of the orbit, the free posterior process of the jugal, and the notched anterior margin of the interclavicle. Phylogenetic analyses using two recently published character-taxon matrices recovered conflicting results for the phylogenetic position of Elachistosuchus-either as an archosauromorph, as a lepidosauromorph or as a more basal, non-saurian diapsid. These different placements highlight the need of a thorough revision of critical taxa and new character sets used for inferring neodiapsid relationships.

Anatomy of the Enigmatic Reptile Elachistosuchus huenei Janensch, 1949 (Reptilia: Diapsida) from the Upper Triassic of Germany and Its Relevance for the Origin of Sauria

PubMed Central

2015-01-01

The holotype and only known specimen of the enigmatic small reptile Elachistosuchus huenei Janensch, 1949 from the Upper Triassic (Norian) Arnstadt Formation of Saxony-Anhalt (Germany) is redescribed using μCT scans of the material. This re-examination revealed new information on the morphology of this taxon, including previously unknown parts of the skeleton such as the palate, braincase, and shoulder girdle. Elachistosuchus is diagnosed especially by the presence of the posterolateral process of the frontal, the extension of the maxillary tooth row to the posterior margin of the orbit, the free posterior process of the jugal, and the notched anterior margin of the interclavicle. Phylogenetic analyses using two recently published character-taxon matrices recovered conflicting results for the phylogenetic position of Elachistosuchus–either as an archosauromorph, as a lepidosauromorph or as a more basal, non-saurian diapsid. These different placements highlight the need of a thorough revision of critical taxa and new character sets used for inferring neodiapsid relationships. PMID:26352985

Modelling gait transition in two-legged animals

NASA Astrophysics Data System (ADS)

Pinto, Carla M. A.; Santos, Alexandra P.

2011-12-01

The study of locomotor patterns has been a major research goal in the last decades. Understanding how intralimb and interlimb coordination works out so well in animals' locomotion is a hard and challenging task. Many models have been proposed to model animal's rhythms. These models have also been applied to the control of rhythmic movements of adaptive legged robots, namely biped, quadruped and other designs. In this paper we study gait transition in a central pattern generator (CPG) model for bipeds, the 4-cells model. This model is proposed by Golubitsky, Stewart, Buono and Collins and is studied further by Pinto and Golubitsky. We briefly resume the work done by Pinto and Golubitsky. We compute numerically gait transition in the 4-cells CPG model for bipeds. We use Morris-Lecar equations and Wilson-Cowan equations as the internal dynamics for each cell. We also consider two types of coupling between the cells: diffusive and synaptic. We obtain secondary gaits by bifurcation of primary gaits, by varying the coupling strengths. Nevertheless, some bifurcating branches could not be obtained, emphasizing the fact that despite analytically those bifurcations exist, finding them is a hard task and requires variation of other parameters of the equations. We note that the type of coupling did not influence the results.

On enigmatic properties of the main belt asteroids

NASA Astrophysics Data System (ADS)

Kochemasov, G.

two warping waves cannot be inscribed in a sphere otherwise than to stretch a body in one direction and to press it in the perpendicular one. Thus, an enigmatic shape of Mars is explained by this way. Asteroids are subjected to a warping action of the wave that bulges one hemisphere and presses the opposite one making convexo-concave bean shape [1]. This wave resonate (1 to 1) with the fundamental wave causing dichotomy of all celestial bodies . This very strong resonance enhances a warping action. That is why asteroids are flat, oblong and bean-shaped. The bulging hemisphere is always cracked, and this cracking sometimes is so strong that "saddles" appear sometimes cutting body into two or more pieces (binaries, satellites). Eros and the small Trojan satellite of Saturn Calypso (PIA07633) are very similar in this typical shape (convexo-concave shape and a "saddle") though they have different compositions, sizes and strengths. It was 1 shown earlier that degassing and rotations of terrestrial planets may be tied by redistribution of their angular momentum between a solid body and its gaseous envelope [2]. Bodies with higher orb. fr. and thus more finely granulated (Mercury, Venus) are more thoroughly wiped out of its volatiles and rotate slower because a significant part of their momenta gone with atmosphere (The Mercury's atmosphere was destroyed by the solar wind). The main asteroid belt rather stretched (2.2-3.2 a.u.) is composed of metallic, stone and carbonaceous bodies (judging by spectra and meteorites) , the first two dominating its inner part, the third -the outer one (similarity with the inner planets in respect of volatiles distribution). Less degassed asteroids keeping their original mass and "original" momentum (i.e.,the larger bodies) differ from the smaller ones having lost their original mass by degassing and spalling and shared their momenta with gone off parts. That is why the larger bodies are fast, the smaller ones slow rotating. References: [1

Quantifying dynamic characteristics of human walking for comprehensive gait cycle.

PubMed

Mummolo, Carlotta; Mangialardi, Luigi; Kim, Joo H

2013-09-01

Normal human walking typically consists of phases during which the body is statically unbalanced while maintaining dynamic stability. Quantifying the dynamic characteristics of human walking can provide better understanding of gait principles. We introduce a novel quantitative index, the dynamic gait measure (DGM), for comprehensive gait cycle. The DGM quantifies the effects of inertia and the static balance instability in terms of zero-moment point and ground projection of center of mass and incorporates the time-varying foot support region (FSR) and the threshold between static and dynamic walking. Also, a framework of determining the DGM from experimental data is introduced, in which the gait cycle segmentation is further refined. A multisegmental foot model is integrated into a biped system to reconstruct the walking motion from experiments, which demonstrates the time-varying FSR for different subphases. The proof-of-concept results of the DGM from a gait experiment are demonstrated. The DGM results are analyzed along with other established features and indices of normal human walking. The DGM provides a measure of static balance instability of biped walking during each (sub)phase as well as the entire gait cycle. The DGM of normal human walking has the potential to provide some scientific insights in understanding biped walking principles, which can also be useful for their engineering and clinical applications.

A Unique Box in 28S rRNA Is Shared by the Enigmatic Insect Order Zoraptera and Dictyoptera

PubMed Central

Dang, Kai; Wu, Haoyang; Wang, Ying; Xie, Qiang; Bu, Wenjun

2013-01-01

The position of the Zoraptera remains one of the most challenging and uncertain concerns in ordinal-level phylogenies of the insects. Zoraptera have been viewed as having a close relationship with five different groups of Polyneoptera, or as being allied to the Paraneoptera or even Holometabola. Although rDNAs have been widely used in phylogenetic studies of insects, the application of the complete 28S rDNA are still scattered in only a few orders. In this study, a secondary structure model of the complete 28S rRNAs of insects was reconstructed based on all orders of Insecta. It was found that one length-variable region, D3-4, is particularly distinctive. The length and/or sequence of D3-4 is conservative within each order of Polyneoptera, but it can be divided into two types between the different orders of the supercohort, of which the enigmatic order Zoraptera and Dictyoptera share one type, while the remaining orders of Polyneoptera share the other. Additionally, independent evidence from phylogenetic results support the clade (Zoraptera+Dictyoptera) as well. Thus, the similarity of D3-4 between Zoraptera and Dictyoptera can serve as potentially valuable autapomorphy or synapomorphy in phylogeny reconstruction. The clades of (Plecoptera+Dermaptera) and ((Grylloblattodea+Mantophasmatodea)+(Embiodea+Phasmatodea)) were also recovered in the phylogenetic study. In addition, considering the other studies based on rDNAs, this study reached the highest congruence with previous phylogenetic studies of Holometabola based on nuclear protein coding genes or morphology characters. Future comparative studies of secondary structures across deep divergences and additional taxa are likely to reveal conserved patterns, structures and motifs that can provide support for major phylogenetic lineages. PMID:23301099

Origin of Enigmatic Galactic-center Filaments Revealed

NASA Astrophysics Data System (ADS)

2004-06-01

Twenty years ago, astronomers discovered a number of enigmatic radio-emitting filaments concentrated near the center of the Milky Way Galaxy. These features initially defied explanation, but a new study of radio images of the Galactic center may point to their possible source. By combining data from the National Science Foundation's Very Large Array (VLA) and Robert C. Byrd Green Bank Telescope (GBT) astronomer Farhad Yusef-Zadeh of Northwestern University has found evidence that at least some of the filaments spring from the concentrated star-formation regions that populate the Galactic center. Galatic Center Combined VLA and GBT image (green) of the Galactic center, with red inset of GBT data only (red). Bright region on right is location of supermassive black hole. Linear filaments are visible above this area. CREDIT: NRAO/AUI/NSF Yusef-Zadeh, et.al. (Click on Image for Larger Version) Yusef-Zadeh presented his findings at the Denver, Colorado, meeting of the American Astronomical Society. William Cotton of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and William Hewitt of Northwestern University also contributed to this research. "Astronomers have long puzzled over the cause of these striking features," said Yusef-Zadeh, "and the turbulent nature of the Galactic center has made detailed analysis difficult. With new multi-wavelength radio images of the Galactic center, however, we can finally see a link between areas of starburst activity and these long-linear filaments." The filaments, which range from 10 to 100 light-years in length and are perhaps little more than 1 to 3 light-years across, occur only in a very narrow area, within approximately two degrees of the Galactic center (which translates to approximately 900 light-years across). Early theories about the origin of these filaments suggested that they were somehow related to the Milky Way’s own magnetic field. This was due to the fact that the first filaments detected

Unravelling the enigmatic origin of calcitic nanofibres in soils and caves: purely physicochemical or biogenic processes?

NASA Astrophysics Data System (ADS)

Bindschedler, S.; Cailleau, G.; Braissant, O.; Millière, L.; Job, D.; Verrecchia, E. P.

2014-05-01

Calcitic nanofibres are ubiquitous habits of secondary calcium carbonate (CaCO3) accumulations observed in calcareous vadose environments. Despite their widespread occurrence, the origin of these nanofeatures remains enigmatic. Three possible mechanisms fuel the debate: (i) purely physicochemical processes, (ii) mineralization of rod-shaped bacteria, and (iii) crystal precipitation on organic templates. Nanofibres can be either mineral (calcitic) or organic in nature. They are very often observed in association with needle fibre calcite (NFC), another typical secondary CaCO3 habit in terrestrial environments. This association has contributed to some confusion between both habits, however they are truly two distinct calcitic features and their recurrent association is likely to be an important fact to help understanding the origin of nanofibres. In this paper the different hypotheses that currently exist to explain the origin of calcitic nanofibres are critically reviewed. In addition to this, a new hypothesis for the origin of nanofibres is proposed based on the fact that current knowledge attributes a fungal origin to NFC. As this feature and nanofibres are recurrently observed together, a possible fungal origin for nanofibres which are associated with NFC is investigated. Sequential enzymatic digestion of the fungal cell wall of selected fungal species demonstrates that the fungal cell wall can be a source of organic nanofibres. The obtained organic nanofibres show a striking morphological resemblance when compared to their natural counterparts, emphasizing a fungal origin for part of the organic nanofibres observed in association with NFC. It is further hypothesized that these organic nanofibres may act as templates for calcite nucleation in a biologically influenced mineralization process, generating calcitic nanofibres. This highlights the possible involvement of fungi in CaCO3 biomineralization processes, a role still poorly documented. Moreover, on a global

Unravelling the enigmatic origin of calcitic nanofibres in soils and caves: purely physicochemical or biogenic processes?

NASA Astrophysics Data System (ADS)

Bindschedler, S.; Cailleau, G.; Braissant, O.; Millière, L.; Job, D.; Verrecchia, E. P.

2014-01-01

Calcitic nanofibres are ubiquitous habits of secondary calcium carbonate (CaCO3) accumulations observed in calcareous vadose environments. Despite their widespread occurrence, the origin of these nanofeatures remains enigmatic. Three possible mechanisms fuel the debate: (i) purely physicochemical processes, (ii) mineralization of rod-shaped bacteria, and (iii) crystal precipitation on organic templates. Nanofibres can be either mineral (calcitic) or organic in nature. They are very often observed in association with Needle Fibre Calcite (NFC), another typical secondary CaCO3 habit in terrestrial environments. This association has contributed to some confusion between both habits, however they are truly two distinct calcitic features and their recurrent association is likely to be an important fact to help understanding the origin of nanofibres. In this manuscript the different hypotheses that currently exist to explain the origin of calcitic nanofibres are critically reviewed. In addition to this, a new hypothesis for the origin of nanofibres is proposed based on the fact that current knowledge attributes a fungal origin to NFC. As this feature and nanofibres are recurrently observed together, a possible fungal origin for nanofibres which are associated with NFC is investigated. Sequential enzymatic digestion of the fungal cell wall of selected fungal species demonstrates that the fungal cell wall can be a source of organic nanofibres. The obtained organic nanofibres show a striking morphological resemblance when compared to their natural counterparts, emphasizing a fungal origin for part of the organic nanofibres observed in association with NFC. It is further hypothesized that these organic nanofibres may act as templates for calcite nucleation in a biologically-influenced mineralization process, generating calcitic nanofibres. This highlights the possible involvement of Fungi in CaCO3 biomineralization processes, a role still poorly documented at present

Research state-of-the-art of mobile robots in China

NASA Astrophysics Data System (ADS)

Wu, Lin; Zhao, Jinglun; Zhang, Peng; Li, Shiqing

1991-03-01

Several newly developed mobile robots in china are described in the paper. It includes masterslave telerobot sixleged robot biped walking robot remote inspection robot crawler moving robot and autonomous mobi le vehicle . Some relevant technology are also described.

Four-Component Catalytic Machinery: Reversible Three-State Control of Organocatalysis by Walking Back and Forth on a Track.

PubMed

Mittal, Nikita; Özer, Merve S; Schmittel, Michael

2018-04-02

A three-component supramolecular walker system is presented where a two-footed ligand (biped) walks back and forth on a tetrahedral 3D track upon the addition and removal of copper(I) ions, respectively. The addition of N-methylpyrrolidine as a catalyst to the walker system generates a four-component catalytic machinery, which acts as a three-state switchable catalytic ensemble in the presence of substrates for a conjugate addition. The copper(I)-ion-initiated walking process of the biped ligand on the track regulates the catalytic activity in three steps: ON versus int ON (intermediate ON) versus OFF. To establish the operation of the four-component catalytic machinery in a mixture of all constituents, forward and backward cycles were performed in situ illustrating that both the walking process and catalytic action are fully reversible and reproducible.

The influence of species, density, and diversity of macroalgal aggregations on microphytobenthic settlement.

PubMed

Umanzor, Schery; Ladah, Lydia; Zertuche-González, José A

2017-10-01

Intertidal macroalgae can modulate their biophysical environment by ameliorating physical conditions and creating habitats. Exploring how seaweed aggregations made up of different species at different densities modify the local environment may help explain how associated organisms respond to the attenuation of extreme physical conditions. Using Silvetia compressa, Chondracanthus canaliculatus, and Pyropia perforata, we constructed monocultures representing the leathery, corticated and foliose functional forms as well as a mixed tri-culture assemblage including the former three, at four densities. Treatment quadrats were installed in the intertidal where we measured irradiance, temperature, particle retention, and water motion underneath the canopies. Additionally, we examined the abundance and richness of the understory microphytobenthos with settlement slides. We found that the density and species composition of the assemblages modulated the amelioration of extreme physical conditions, with macroalgal aggregations of greater structural complexity due to their form and density showing greater physical factor attenuation. However, increasing the number of species within a patch did not directly result in increased complexity and therefore, did not necessarily cause greater amelioration of the environment. Microphytobenthic composition was also affected by species composition and density, with higher abundances under S. compressa and C. canaliculatus canopies at high and mid densities. These results support the idea that the environmental modifications driven by these macroalgae have a significant effect on the dynamics of the intertidal environment by promoting distinct temporal and spatial patchiness in the microphytobenthos, with potentially significant effects on the overall productivity of these ecosystems. © 2017 Phycological Society of America.

The Enigmatic Bench Unit of Endeavour Crater Rim in Meridiani Planum, Mars

NASA Astrophysics Data System (ADS)

Ruff, S. W.

2013-12-01

Cape York bench clearly presents Grasberg rocks above Burns rocks. Erosion of a plunging synclinal form could explain this apparent inverted relationship, or it reveals that the Grasberg unit is younger than Burns formation. But this latter interpretation implies that Grasberg rocks, which have been observed only at the Endeavour rim, have been stripped off of Burns formation everywhere else. The Grasberg bench unit has recently been encountered in an isthmus setting between two low knobs of presumed Shoemaker formation called Nobbys Head and Sutherland Point just south of Cape York. The isthmus also presents Grasberg as topographically elevated above the Burns formation rocks. Despite its broad, smooth exposure, no remnants of Burns formation have been found on top of Grasberg at this location or anywhere on the Cape York bench. So the stratigraphic relationship between Grasberg and Burns rocks remains enigmatic. At the time of writing, Opportunity is at the edge of Solander Point, another bench feature on the northern tip of a rim segment known as Cape Tribulation. The erosional expression of this example appears different from those examined previously and perhaps offers the best chance to understand stratigraphic relationships. 1. S. W. Squyres et al., Ancient impact and aqueous processes at Endeavour Crater, Mars. Science 336, 570 (2012).

The evolution of armadillos, anteaters and sloths depicted by nuclear and mitochondrial phylogenies: implications for the status of the enigmatic fossil Eurotamandua.

PubMed

Delsuc, F; Catzeflis, F M; Stanhope, M J; Douzery, E J

2001-08-07

The mammalian order Xenarthra (armadillos, anteaters and sloths) is one of the four major clades of placentals, but it remains poorly studied from the molecular phylogenetics perspective. We present here a study encompassing most of the order's diversity in order to establish xenarthrans' intra-ordinal relationships, discuss the evolution of their morphological characters, search for their extant sister group and specify the timing of their radiation with special emphasis on the status of the controversial fossil Eurotamandua. Sequences of three genes (nuclear exon 28 of the Von Willebrand factor and mitochondrial 12S and 16S rRNAs) are compared for eight of the 13 living genera. Phylogenetic analyses confirm the order's monophyly and that of its three major lineages: armadillos (Cingulata), anteaters (Vermilingua) and sloths ('Tardigrada', renamed in 'Folivora'), and our results strongly support the grouping of hairy xenarthrans (anteaters and sloths) into Pilosa. Within placentals, Afrotheria might be the first lineage to branch off, followed by Xenarthra. The morphological adaptative convergence between New World xenarthrans and Old World pangolins is confirmed. Molecular datings place the early emergence of armadillos around the Cretaceous/Tertiary boundary, followed by the divergence between anteaters and sloths in the Early Eocene era. These Tertiary dates contradict the concept of a very ancient origin of modern xenarthran lineages. They also question the placement of the purported fossil anteater (Eurotamandua) from the Middle Eocene period of Europe with the Vermilingua and instead suggest the independent and convergent evolution of this enigmatic taxon.

New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation

PubMed Central

2014-01-01

Background The origin and early radiation of archosaurs and closely related taxa (Archosauriformes) during the Triassic was a critical event in the evolutionary history of tetrapods. This radiation led to the dinosaur-dominated ecosystems of the Jurassic and Cretaceous, and the high present-day archosaur diversity that includes around 10,000 bird and crocodylian species. The timing and dynamics of this evolutionary radiation are currently obscured by the poorly constrained phylogenetic positions of several key early archosauriform taxa, including several species from the Middle Triassic of Argentina (Gracilisuchus stipanicicorum) and China (Turfanosuchus dabanensis, Yonghesuchus sangbiensis). These species act as unstable ‘wildcards’ in morphological phylogenetic analyses, reducing phylogenetic resolution. Results We present new anatomical data for the type specimens of G. stipanicicorum, T. dabanensis, and Y. sangbiensis, and carry out a new morphological phylogenetic analysis of early archosaur relationships. Our results indicate that these three previously enigmatic taxa form a well-supported clade of Middle Triassic archosaurs that we refer to as Gracilisuchidae. Gracilisuchidae is placed basally within Suchia, among the pseudosuchian (crocodile-line) archosaurs. The approximately contemporaneous and morphologically similar G. stipanicicorum and Y. sangbiensis may be sister taxa within Gracilisuchidae. Conclusions Our results provide increased resolution of the previously poorly constrained relationships of early archosaurs, with increased levels of phylogenetic support for several key early pseudosuchian clades. Moreover, they falsify previous hypotheses suggesting that T. dabanensis and Y. sangbiensis are not members of the archosaur crown group. The recognition of Gracilisuchidae provides further support for a rapid phylogenetic diversification of crown archosaurs by the Middle Triassic. The disjunct distribution of the gracilisuchid clade in China and

New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation.

PubMed

Butler, Richard J; Sullivan, Corwin; Ezcurra, Martín D; Liu, Jun; Lecuona, Agustina; Sookias, Roland B

2014-06-10

The origin and early radiation of archosaurs and closely related taxa (Archosauriformes) during the Triassic was a critical event in the evolutionary history of tetrapods. This radiation led to the dinosaur-dominated ecosystems of the Jurassic and Cretaceous, and the high present-day archosaur diversity that includes around 10,000 bird and crocodylian species. The timing and dynamics of this evolutionary radiation are currently obscured by the poorly constrained phylogenetic positions of several key early archosauriform taxa, including several species from the Middle Triassic of Argentina (Gracilisuchus stipanicicorum) and China (Turfanosuchus dabanensis, Yonghesuchus sangbiensis). These species act as unstable 'wildcards' in morphological phylogenetic analyses, reducing phylogenetic resolution. We present new anatomical data for the type specimens of G. stipanicicorum, T. dabanensis, and Y. sangbiensis, and carry out a new morphological phylogenetic analysis of early archosaur relationships. Our results indicate that these three previously enigmatic taxa form a well-supported clade of Middle Triassic archosaurs that we refer to as Gracilisuchidae. Gracilisuchidae is placed basally within Suchia, among the pseudosuchian (crocodile-line) archosaurs. The approximately contemporaneous and morphologically similar G. stipanicicorum and Y. sangbiensis may be sister taxa within Gracilisuchidae. Our results provide increased resolution of the previously poorly constrained relationships of early archosaurs, with increased levels of phylogenetic support for several key early pseudosuchian clades. Moreover, they falsify previous hypotheses suggesting that T. dabanensis and Y. sangbiensis are not members of the archosaur crown group. The recognition of Gracilisuchidae provides further support for a rapid phylogenetic diversification of crown archosaurs by the Middle Triassic. The disjunct distribution of the gracilisuchid clade in China and Argentina demonstrates that early

Phylogenetic relationships among amphisbaenian reptiles based on complete mitochondrial genomic sequences.

PubMed

Macey, J Robert; Papenfuss, Theodore J; Kuehl, Jennifer V; Fourcade, H Mathew; Boore, Jeffrey L

2004-10-01

Complete mitochondrial genomic sequences are reported from 12 members in the four families of the reptile group Amphisbaenia. Analysis of 11,946 aligned nucleotide positions (5797 informative) produces a robust phylogenetic hypothesis. The family Rhineuridae is basal and Bipedidae is the sister taxon to the Amphisbaenidae plus Trogonophidae. Amphisbaenian reptiles are surprisingly old, predating the breakup of Pangaea 200 million years before present, because successive basal taxa (Rhineuridae and Bipedidae) are situated in tectonic regions of Laurasia and nested taxa (Amphisbaenidae and Trogonophidae) are found in Gondwanan regions. Thorough sampling within the Bipedidae shows that it is not tectonic movement of Baja California away from the Mexican mainland that is primary in isolating Bipes species, but rather that primary vicariance occurred between northern and southern groups. Amphisbaenian families show parallel reduction in number of limbs and Bipes species exhibit parallel reduction in number of digits. A measure is developed for comparing the phylogenetic information content of various genes. A synapomorphic trait defining the Bipedidae is a shift from the typical vertebrate mitochondrial gene arrangement to the derived state of trnE and nad6. In addition, a tandem duplication of trnT and trnP is observed in Bipes biporus with a pattern of pseudogene formation that varies among populations. The first case of convergent rearrangement of the mitochondrial genome among animals demonstrated by complete genomic sequences is reported. Relative to most vertebrates, the Rhineuridae has the block nad6, trnE switched in order with the block cob, trnT, trnP, as they are in birds.

Rediscovery of the enigmatic fungus-farming ant "Mycetosoritis" asper Mayr (Hymenoptera: Formicidae): Implications for taxonomy, phylogeny, and the evolution of agriculture in ants

PubMed Central

Ješovnik, Ana; Vasconcelos, Heraldo L.; Bacci, Mauricio; Schultz, Ted R.

2017-01-01

We report the rediscovery of the exceedingly rarely collected and enigmatic fungus-farming ant species Mycetosoritis asper. Since the description of the type specimen in 1887, only four additional specimens are known to have been added to the world's insect collections. Its biology is entirely unknown and its phylogenetic position within the fungus-farming ants has remained puzzling due to its aberrant morphology. In 2014 we excavated and collected twenty-one colonies of M. asper in the Floresta Nacional de Chapecó in Santa Catarina, Brazil. We describe here for the first time the male and larva of the species and complement the previous descriptions of both the queen and the worker. We describe, also for the first time, M. asper biology, nest architecture, and colony demographics, and identify its fungal cultivar. Molecular phylogenetic analyses indicate that both M. asper and M. clorindae are members of the genus Cyphomyrmex, which we show to be paraphyletic as currently defined. More precisely, M. asper is a member of the Cyphomyrmex strigatus group, which we also show to be paraphyletic with respect to the genus Mycetophylax. Based on these results, and in the interest of taxonomic stability, we transfer the species M. asper, M. clorindae, and all members of the C. strigatus group to the genus Mycetophylax, the oldest available name for this clade. Based on ITS sequence data, Mycetophylax asper practices lower agriculture, cultivating a fungal species that belongs to lower-attine fungal Clade 2, subclade F. PMID:28489860

Conway Morris: Extraterrestrials: Aliens like us?

NASA Astrophysics Data System (ADS)

Morris, Simon Conway

2005-08-01

So what are they going to be like, those long-expected extraterrestrials? Hideous hydrocarbon arachnoids, waving laser cannons as they chase screaming humans, repulsively surveying the scene through empathy-free compound eyes? Or maybe laughing bipeds, chatting away, holding a glass of wine, a bit like us?

The evolution of armadillos, anteaters and sloths depicted by nuclear and mitochondrial phylogenies: implications for the status of the enigmatic fossil Eurotamandua.

PubMed Central

Delsuc, F.; Catzeflis, F. M.; Stanhope, M. J.; Douzery, E. J.

2001-01-01

The mammalian order Xenarthra (armadillos, anteaters and sloths) is one of the four major clades of placentals, but it remains poorly studied from the molecular phylogenetics perspective. We present here a study encompassing most of the order's diversity in order to establish xenarthrans' intra-ordinal relationships, discuss the evolution of their morphological characters, search for their extant sister group and specify the timing of their radiation with special emphasis on the status of the controversial fossil Eurotamandua. Sequences of three genes (nuclear exon 28 of the Von Willebrand factor and mitochondrial 12S and 16S rRNAs) are compared for eight of the 13 living genera. Phylogenetic analyses confirm the order's monophyly and that of its three major lineages: armadillos (Cingulata), anteaters (Vermilingua) and sloths ('Tardigrada', renamed in 'Folivora'), and our results strongly support the grouping of hairy xenarthrans (anteaters and sloths) into Pilosa. Within placentals, Afrotheria might be the first lineage to branch off, followed by Xenarthra. The morphological adaptative convergence between New World xenarthrans and Old World pangolins is confirmed. Molecular datings place the early emergence of armadillos around the Cretaceous/Tertiary boundary, followed by the divergence between anteaters and sloths in the Early Eocene era. These Tertiary dates contradict the concept of a very ancient origin of modern xenarthran lineages. They also question the placement of the purported fossil anteater (Eurotamandua) from the Middle Eocene period of Europe with the Vermilingua and instead suggest the independent and convergent evolution of this enigmatic taxon. PMID:11487408

The Enigmatic Neutrino

ERIC Educational Resources Information Center

Lincoln, Don; Miceli, Tia

2015-01-01

Through a century of work, physicists have refined a model to describe all fundamental particles, the forces they share, and their interactions on a microscopic scale. This masterpiece of science is called the Standard Model. While this theory is incredibly powerful, we know of at least one particle that exhibits behaviors that are outside of its…

Precambrian fluvial deposits: Enigmatic palaeohydrological data from the c. 2 1.9 Ga Waterberg Group, South Africa

NASA Astrophysics Data System (ADS)

Eriksson, Patrick G.; Bumby, Adam J.; Brümer, Jacobus J.; van der Neut, Markus

2006-08-01

a combination of major global-scale tectono-thermal and atmospheric-palaeoclimatic events, a simpler explanation of these apparently enigmatic palaeoslope values may be pertinent. Of the two possible palaeohydrological formulae for calculating palaeoslope, one provides results close to typical fluvial gradients; the other formula relies on preserved channel-width data. We suggest that the latter will not be reliable due to problematic preservation of original channel-widths within an active braided fluvial system. We thus find no unequivocal support for a unique fluvial style for the Precambrian, beyond that generally accepted for that period and discussed briefly in the first paragraph.

Defining the Scope of Systems of Care: An Ecological Perspective

ERIC Educational Resources Information Center

Cook, James R.; Kilmer, Ryan P.

2010-01-01

The definition of a system of care (SOC) can guide those intending to develop and sustain SOCs. Hodges, Ferreira, Israel, and Mazza [Hodges, S., Ferreira, K., Israel, N., & Mazza, J. (in press). "Systems of care, featherless bipeds, and the measure of all things." "Evaluation and Program Planning"] have emphasized contexts in which services are…

An Algorithm for Pedestrian Detection in Multispectral Image Sequences

NASA Astrophysics Data System (ADS)

Kniaz, V. V.; Fedorenko, V. V.

2017-05-01

The growing interest for self-driving cars provides a demand for scene understanding and obstacle detection algorithms. One of the most challenging problems in this field is the problem of pedestrian detection. Main difficulties arise from a diverse appearances of pedestrians. Poor visibility conditions such as fog and low light conditions also significantly decrease the quality of pedestrian detection. This paper presents a new optical flow based algorithm BipedDetet that provides robust pedestrian detection on a single-borad computer. The algorithm is based on the idea of simplified Kalman filtering suitable for realization on modern single-board computers. To detect a pedestrian a synthetic optical flow of the scene without pedestrians is generated using slanted-plane model. The estimate of a real optical flow is generated using a multispectral image sequence. The difference of the synthetic optical flow and the real optical flow provides the optical flow induced by pedestrians. The final detection of pedestrians is done by the segmentation of the difference of optical flows. To evaluate the BipedDetect algorithm a multispectral dataset was collected using a mobile robot.

A three-dimensional morphometric analysis of upper forelimb morphology in the enigmatic tapir (Perissodactyla: Tapirus) hints at subtle variations in locomotor ecology.

PubMed

MacLaren, Jamie A; Nauwelaerts, Sandra

2016-11-01

Forelimb morphology is an indicator for terrestrial locomotor ecology. The limb morphology of the enigmatic tapir (Perissodactyla: Tapirus) has often been compared to that of basal perissodactyls, despite the lack of quantitative studies comparing forelimb variation in modern tapirs. Here, we present a quantitative assessment of tapir upper forelimb osteology using three-dimensional geometric morphometrics to test whether the four modern tapir species are monomorphic in their forelimb skeleton. The shape of the upper forelimb bones across four species (T. indicus; T. bairdii; T. terrestris; T. pinchaque) was investigated. Bones were laser scanned to capture surface morphology and 3D landmark analysis was used to quantify shape. Discriminant function analyses were performed to reveal features which could be used for interspecific discrimination. Overall our results show that the appendicular skeleton contains notable interspecific differences. We demonstrate that upper forelimb bones can be used to discriminate between species (>91% accuracy), with the scapula proving the most diagnostic bone (100% accuracy). Features that most successfully discriminate between the four species include the placement of the cranial angle of the scapula, depth of the humeral condyle, and the caudal deflection of the olecranon. Previous studies comparing the limbs of T. indicus and T. terrestris are corroborated by our quantitative findings. Moreover, the mountain tapir T. pinchaque consistently exhibited the greatest divergence in morphology from the other three species. Despite previous studies describing tapirs as functionally mediportal in their locomotor style, we find osteological evidence suggesting a spectrum of locomotor adaptations in the tapirs. We conclude that modern tapir forelimbs are neither monomorphic nor are tapirs as conserved in their locomotor habits as previously described. J. Morphol. 277:1469-1485, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals

Phylogenetic position of the enigmatic clawless eutardigrade genus Apodibius Dastych, 1983 (Tardigrada), based on 18S and 28S rRNA sequence data from its type species A. confusus.

PubMed

Dabert, Miroslawa; Dastych, Hieronymus; Hohberg, Karin; Dabert, Jacek

2014-01-01

The systematics of Eutardigrada, the largest lineage among the three classes of the phylum Tardigrada, is based mainly on the morphology of the leg claws and of the buccal apparatus. However, three members of the rarely recorded and poorly known limno-terrestrial eutardigrade genus Apodibius have no claws on their strongly reduced legs, a unique character among all tardigrades. This absence of all claws makes the systematic position of Apodibius one of the most enigmatic among the whole class. Until now all known associates of the genus Apodibius have been located in the incertae sedis species group or, quite recently, included into the Necopinatidae family. In the present study, phylogenetic analyses of 18S and 28S rRNA sequence data from 31 tardigrade species representing four parachelan superfamilies (Isohypsibioidea, Hypsibioidea, Macrobiotoidea, Eohypsibioidea), the apochelan Milnesium tardigradum, and the type species of the genus Apodibius, A. confusus, indicated close relationship of the Apodibius with tardigrade species recently included in the superfamily Isohypsibioidea. This result was well-supported and consistent across all markers (separate 18S rRNA, 28S rRNA, and combined 18S rRNA+28S rRNA datasets) and methods (MP, ML) applied. Copyright © 2013 Elsevier Inc. All rights reserved.

On the Origin of Reverse Transcriptase-Using CRISPR-Cas Systems and Their Hyperdiverse, Enigmatic Spacer Repertoires.

PubMed

Silas, Sukrit; Makarova, Kira S; Shmakov, Sergey; Páez-Espino, David; Mohr, Georg; Liu, Yi; Davison, Michelle; Roux, Simon; Krishnamurthy, Siddharth R; Fu, Becky Xu Hua; Hansen, Loren L; Wang, David; Sullivan, Matthew B; Millard, Andrew; Clokie, Martha R; Bhaya, Devaki; Lambowitz, Alan M; Kyrpides, Nikos C; Koonin, Eugene V; Fire, Andrew Z

2017-07-11

analysis of available bacterial sequence data, we find evidence that RT-based RNA adaptation machinery has been able to join with CRISPR-Cas immune systems in many, diverse bacterial species. To investigate whether the abilities to adapt to DNA and RNA molecules are utilized for defense against distinct classes of invaders in nature, we sequenced CRISPR arrays from samples of commercial-scale open-air cultures of Arthrospira platensis , a cyanobacterium that contains both RT-lacking and RT-containing CRISPR-Cas systems. We uncovered a diverse pool of naturally occurring immune memories, with the RT-lacking locus acquiring a number of segments matching known viral or bacterial genes, while the RT-containing locus has acquired spacers from a distinct sequence pool for which the source remains enigmatic. Copyright © 2017 Silas et al.

The enigmatic ichnofossil Tisoa siphonalis and widespread authigenic seep carbonate formation during the Late Pliensbachian in southern France

NASA Astrophysics Data System (ADS)

van de Schootbrugge, B.; Harazim, D.; Sorichter, K.; Oschmann, W.; Fiebig, J.; Püttmann, W.; Peinl, M.; Zanella, F.; Teichert, B. M. A.; Hoffmann, J.; Stadnitskaia, A.; Rosenthal, Y.

2010-10-01

Tubular carbonate concretions of up to 1 m in length and perpendicular to bedding, occur abundantly in the Upper Pliensbachian (upper Amaltheus margaritatus Zone, Gibbosus Subzone) in outcrops (Fontaneilles section) in the vicinity of Rivière-sûr-Tarn, southern France. Stable isotope analyses of these concretions show negative δ13C values that decrease from the rim to the center from -18.8‰ to -25.7‰ (V-PDB), but normal marine δ18O values (-1.8‰). Carbon isotope analyses of Late Pliensbachian bulk carbonate (matrix) samples from the Fontaneilles section show clearly decreasing C-isotope values across the A. margaritatus Zone, from +1‰ to -3‰ (V-PDB). Isotope analyses of coeval belemnite rostra do not document such a negative C-isotope trend with values remaining stable around +2‰ (V-PDB). Computer tomographic (CT) scanning of the tubular concretions show multiple canals that are lined or filled entirely with pyrite. Previously, the formation of these concretions with one, two, or more central tubes, has been ascribed to the activity of an enigmatic organism, possibly with annelid or arthropod affinities, known asTisoa siphonalis. Our results suggest tisoan structures are abiogenic. Based on our geochemical analyses and sedimentological observations we suggest that these concretions formed as a combination of the anaerobic oxidation of methane (AOM) and sulfate reduction within the sediment. Fluids rich in methane and/or hydrocarbons likely altered local bulk rock carbon isotope records, but did not affect the global carbon cycle. Interestingly, Tisoa siphonalis has been described from many locations in the Grands Causses Basin in southern France, and from northern France and Luxemburg, always occurring at the same stratigraphic level. Upper Pliensbachian authigenic carbonates thus possibly cover an area of many thousand square kilometers. Greatly reduced sedimentation rates are needed to explain the stabilization of the sulfate-methane transition

The enigmatic ichnofossil Tisoa siphonalis and widespread authigenic seep carbonate formation during the Late Pliensbachian in southern France

NASA Astrophysics Data System (ADS)

van de Schootbrugge, B.; Harazim, D.; Sorichter, K.; Oschmann, W.; Fiebig, J.; Püttmann, W.; Peinl, M.; Zanella, F.; Teichert, B.; Hoffmann, J.; Stadnitskaia, A.; Rosenthal, Y.

2010-06-01

Tubular carbonate concretions of up to 1 m in length and perpendicular to bedding, occur abundantly in the Upper Pliensbachian (upper Amaltheus margaritatus Zone, Gibbosus Subzone) in outcrops (Fontaneilles section) in the vicinity of Rivière-sûr-Tarn, southern France. Stable isotope analyses of these concretions show negative &delta13C values that decrease from the rim to the center from -18.8‰ to -25.7‰ (V-PDB), but normal marine δ18O values (-1.8‰). Carbon isotope analyses of Late Pliensbachian bulk carbonate (matrix) samples from the Fontaneilles section show clearly decreasing C-isotope values across the A. margaritatus Zone, from +1‰ to -3‰ (V-PDB). Isotope analyses of coeval belemnite rostra do not document such a negative C-isotope trend with values remaining stable around +2‰ (V-PDB). Computer tomographic (CT) scanning of the tubular concretions show multiple canals that are lined or filled entirely with pyrite. Previously, the formation of these concretions with one, two, or more central tubes, has been ascribed to the activity of an enigmatic organism, possibly with annelid or arthropod affinities, known as Tisoa siphonalis. Our results suggest tisoan structures are abiogenic. Based on our geochemical analyses and sedimentological observations we suggest that these concretions formed as a combination of the anaerobic oxidation of methane (AOM) and sulfate reduction within the sediment. Fluids rich in methane and/or hydrocarbons likely altered local bulk rock carbon isotope records, but did not affect the global carbon cycle. Interestingly, Tisoa siphonalis has been described from many locations in the Grands Causses Basin in southern France, and from northern France and Luxemburg, always occurring at the same stratigraphic level. Upper Pliensbachian authigenic carbonates thus possibly cover an area of many thousand square kilometers. Greatly reduced sedimentation rates are needed to explain the stabilization of the sulfate

Another Look at an Enigmatic New World

NASA Astrophysics Data System (ADS)

2005-02-01

centred at 2 microns. On the right is the NACO/SDI image of the same location showing Titan's surface through the 1.6 micron methane window. A spherical projection with coordinates on Titan is overplotted. ESO PR Photo 04b/05 is a map of Titan taken with NACO at 1.28 micron (a methane window allowing it to probe down to the surface). On the leading side of Titan, the bright equatorial feature ("Xanadu") is dominating. On the trailing side, the landing site of the Huygens probe is indicated. ESO PR Photo 04c/05 ESO PR Photo 04c/05 Titan, the Enigmatic Moon, and Huygens Landing Site (NACO-SDI/VLT and Cassini/ISS) [Preview - JPEG: 400 x 589 pix - 40k] [Normal - JPEG: 800 x 1178 pix - 290k] Caption: ESO PR Photo 04c/05 is a comparison between the NACO/SDI image and an image taken by Cassini/ISS while approaching Titan. The Cassini image shows the Huygens landing site map wrapped around Titan, rotated to the same position as the January NACO SDI observations. The yellow "X" marks the landing site of the ESA Huygens probe. The Cassini/ISS image is courtesy of NASA, JPL, Space Science Institute (see http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=36222). The coloured lines delineate the regions that were imaged by Cassini at differing resolutions. The lower-resolution imaging sequences are outlined in blue. Other areas have been specifically targeted for moderate and high resolution mosaicking of surface features. These include the site where the European Space Agency's Huygens probe has touched down in mid-January (marked with the yellow X), part of the bright region named Xanadu (easternmost extent of the area covered), and a boundary between dark and bright regions. ESO PR Photo 04d/05 ESO PR Photo 04d/05 Evolution of the Atmosphere of Titan (NACO/VLT) [Preview - JPEG: 400 x 902 pix - 40k] [Normal - JPEG: 800 x 1804 pix - 320k] Caption: ESO PR Photo 04d/05 is an image of Titan's atmosphere at 2.12 microns as observed with NACO on the VLT at three different epochs

Three new species of glass sponges Pheronematidae (Porifera: Hexactinellida) from the deep-sea of the northwestern Pacific Ocean.

PubMed

Wang, Dexiang; Wang, Chunsheng; Zhang, Yuan; Liu, Chenggang

2016-09-29

Three new glass sponge species of the family Pheronematidae are described in this study. Specimens were sampled in the northwestern Pacific Ocean during cruise DY125-35I expedition (July-August, 2014) conducted by the China Ocean Mineral Resources R&D Association. All samples were collected by the Chinese manned submersible Jiaolong HOV at a depth of 1627-2897 m. The three species belonging to three genera of the same family were observed, i.e., Platylistrum subviridum sp. nov. Poliopogon canaliculatus sp. nov. and Semperella retrospinella sp. nov. An unique form of the pinular ray of pinular pentactins with reclined spines is described for S. retrospinella sp. nov. This is also the first record of Platylistrum in the Pacific Ocean.

Examining the Enigmatic Einstein

ERIC Educational Resources Information Center

Khoon, Koh Aik

2007-01-01

Albert Einstein is the icon of scientific genius. His is one the most recognizable faces in the history of mankind. This paper takes a cursory look at the man who is commonly perceived to be the epitome of eccentricity. We manage to sum up his salient traits which are associated with his name. The traits are based on anecdotal evidence. This…

Enigmatic, ultrasmall, uncultivated Archaea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Brett J.; Comolli, Luis; Dick, Gregory J.

Metagenomics has provided access to genomes of as yet uncultivated microorganisms in natural environments, yet there are gaps in our knowledge particularly for Archaea that occur at relatively low abundance and in extreme environments. Ultrasmall cells (<500 nm in diameter) from lineages without cultivated representatives that branch near the crenarchaeal/euryarchaeal divide have been detected in a variety of acidic ecosystems. We reconstructed composite, near-complete 1-Mb genomes for three lineages, referred to as ARMAN (archaeal Richmond Mine acidophilic nanoorganisms), from environmental samples and a biofilm filtrate. Genes of two lineages are among the smallest yet described, enabling a 10% higher codingmore » density than found genomes of the same size, and there are noncontiguous genes. No biological function could be inferred for up to 45% of genes and no more than 63% of the predicted proteins could be assigned to a revised set of archaeal clusters of orthologous groups. Some core metabolic genes are more common in Crenarchaeota than Euryarchaeota, up to 21% of genes have the highest sequence identity to bacterial genes, and 12 belong to clusters of orthologous groups that were previously exclusive to bacteria. A small subset of 3D cryo-electron tomographic reconstructions clearly show penetration of the ARMAN cell wall and cytoplasmic membranes by protuberances extended from cells of the archaeal order Thermoplasmatales. Interspecies interactions, the presence of a unique internal tubular organelle [Comolli, et al. (2009) ISME J 3:159 167], and many genes previously only affiliated with Crenarchaea or Bacteria indicate extensive unique physiology in organisms that branched close to the time that Cren- and Euryarchaeotal lineages diverged.« less

Enigmatic, ultrasmall, uncultivated Archaea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Brett J.; Comolli, Luis; Dick, Gregory J.

Metagenomics has provided access to genomes of as yet uncultivated microorganisms in natural environments, yet there are gaps in our knowledge-particularly for Archaea-that occur at relatively low abundance and in extreme environments. Ultrasmall cells (<500 nm in diameter) from lineages without cultivated representatives that branch near the crenarchaeal/euryarchaeal divide have been detected in a variety of acidic ecosystems. We reconstructed composite, near-complete similar to 1-Mb genomes for three lineages, referred to as ARMAN (archaeal Richmond Mine acidophilic nanoorganisms), from environmental samples and a biofilm filtrate. Genes of two lineages are among the smallest yet described, enabling a 10% higher codingmore » density than found genomes of the same size, and there are noncontiguous genes. No biological function could be inferred for up to 45% of genes and no more than 63% of the predicted proteins could be assigned to a revised set of archaeal clusters of orthologous groups. Some core metabolic genes are more common in Crenarchaeota than Euryarchaeota, up to 21% of genes have the highest sequence identity to bacterial genes, and 12 belong to clusters of orthologous groups that were previously exclusive to bacteria. A small subset of 3D cryo-electron tomographic reconstructions clearly show penetration of the ARMAN cell wall and cytoplasmic membranes by protuberances extended from cells of the archaeal order Thermoplasmatales. Interspecies interactions, the presence of a unique internal tubular organelle [Comolli, et al. (2009) ISME J 3: 159-167], and many genes previously only affiliated with Crenarchaea or Bacteria indicate extensive unique physiology in organisms that branched close to the time that Cren- and Euryarchaeotal lineages diverged.« less

The Enigmatic Mr Gove

ERIC Educational Resources Information Center

Barker, Bernard

2013-01-01

Michael Gove's personal tastes and priorities dominate the education landscape as he drives through reforms designed to ensure that every child has the opportunity to learn "the best that has been thought and said" as a foundation for upward social mobility. This article examines the coherence and progress of the government's reform…

The enigmatic archaeal virosphere.

PubMed

Prangishvili, David; Bamford, Dennis H; Forterre, Patrick; Iranzo, Jaime; Koonin, Eugene V; Krupovic, Mart

2017-11-10

One of the most prominent features of archaea is the extraordinary diversity of their DNA viruses. Many archaeal viruses differ substantially in morphology from bacterial and eukaryotic viruses and represent unique virus families. The distinct nature of archaeal viruses also extends to the gene composition and architectures of their genomes and the properties of the proteins that they encode. Environmental research has revealed prominent roles of archaeal viruses in influencing microbial communities in ocean ecosystems, and recent metagenomic studies have uncovered new groups of archaeal viruses that infect extremophiles and mesophiles in diverse habitats. In this Review, we summarize recent advances in our understanding of the genomic and morphological diversity of archaeal viruses and the molecular biology of their life cycles and virus-host interactions, including interactions with archaeal CRISPR-Cas systems. We also examine the potential origins and evolution of archaeal viruses and discuss their place in the global virosphere.

Enigmatic insight into collagen

PubMed Central

Deshmukh, Shrutal Narendra; Dive, Alka M; Moharil, Rohit; Munde, Prashant

2016-01-01

Collagen is a unique, triple helical molecule which forms the major part of extracellular matrix. It is the most abundant protein in the human body, representing 30% of its dry weight. It is the fibrous structural protein that makes up the white fibers (collagen fibers) of skin, tendons, bones, cartilage and all other connective tissues. Collagens are not only essential for the mechanical resistance and resilience of multicellular organisms, but are also signaling molecules defining cellular shape and behavior. The human body has at least 16 types of collagen, but the most prominent types are I, II and III. Collagens are produced by several cell types and are distinguishable by their molecular compositions, morphologic characteristics, distribution, functions and pathogenesis. This is the major fibrous glycoprotein present in the extracellular matrix and in connective tissue and helps in maintaining the structural integrity of these tissues. It has a triple helical structure. Various studies have proved that mutations that modify folding of the triple helix result in identifiable genetic disorders. Collagen diseases share certain similarities with autoimmune diseases, because autoantibodies specific to each collagen disease are produced. Therefore, this review highlights the role of collagen in normal health and also the disorders associated with structural and functional defects in collagen. PMID:27601823

Optimal bipedal interactions with dynamic terrain: synthesis and analysis via nonlinear programming

NASA Astrophysics Data System (ADS)

Hubicki, Christian; Goldman, Daniel; Ames, Aaron

In terrestrial locomotion, gait dynamics and motor control behaviors are tuned to interact efficiently and stably with the dynamics of the terrain (i.e. terradynamics). This controlled interaction must be particularly thoughtful in bipeds, as their reduced contact points render them highly susceptible to falls. While bipedalism under rigid terrain assumptions is well-studied, insights for two-legged locomotion on soft terrain, such as sand and dirt, are comparatively sparse. We seek an understanding of how biological bipeds stably and economically negotiate granular media, with an eye toward imbuing those abilities in bipedal robots. We present a trajectory optimization method for controlled systems subject to granular intrusion. By formulating a large-scale nonlinear program (NLP) with reduced-order resistive force theory (RFT) models and jamming cone dynamics, the optimized motions are informed and shaped by the dynamics of the terrain. Using a variant of direct collocation methods, we can express all optimization objectives and constraints in closed-form, resulting in rapid solving by standard NLP solvers, such as IPOPT. We employ this tool to analyze emergent features of bipedal locomotion in granular media, with an eye toward robotic implementation.

Evaluating alternative gait strategies using evolutionary robotics.

PubMed

Sellers, William I; Dennis, Louise A; W -J, Wang; Crompton, Robin H

2004-05-01

Evolutionary robotics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robot is predefined and various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requirements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance parameters such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictions for modern humans are highly accurate in terms of energy cost for a given speed and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human-like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominids.

The functional origin of dinosaur bipedalism: Cumulative evidence from bipedally inclined reptiles and disinclined mammals.

PubMed

Persons, W Scott; Currie, Philip J

2017-05-07

Bipedalism is a trait basal to, and widespread among, dinosaurs. It has been previously argued that bipedalism arose in the ancestors of dinosaurs for the function of freeing the forelimbs to serve as predatory weapons. However, this argument does not explain why bipedalism was retained among numerous herbivorous groups of dinosaurs. We argue that bipedalism arose in the dinosaur line for the purpose of enhanced cursoriality. Modern facultatively bipedal lizards offer an analog for the first stages in the evolution of dinosaurian bipedalism. Many extant lizards assume a bipedal stance while attempting to flee predators at maximum speed. Bipedalism, when combined with a caudofemoralis musculature, has cursorial advantages because the caudofemoralis provides a greater source of propulsion to the hindlimbs than is generally available to the forelimbs. That cursorial advantage explains the relative abundance of cursorial facultative bipeds and obligate bipeds among fossil diapsids and the relative scarcity of either among mammals. Having lost their caudofemoralis in the Permian, perhaps in the context of adapting to a fossorial lifestyle, the mammalian line has been disinclined towards bipedalism, but, having never lost the caudofemoralis of their ancestors, cursorial avemetatarsalians (bird-line archosaurs) were naturally inclined towards bipedalism. Copyright © 2017 Elsevier Ltd. All rights reserved.

Kinematically stable bipedal locomotion using ionic polymer-metal composite actuators

NASA Astrophysics Data System (ADS)

Hosseinipour, Milad; Elahinia, Mohammad

2013-08-01

Ionic conducting polymer-metal composites (abbreviated as IPMCs) are interesting actuators that can act as artificial muscles in robotic and microelectromechanical systems. Various black or gray box models have modeled the electrochemical-mechanical behavior of these materials. In this study, the governing partial differential equation of the behavior of IPMCs is solved using finite element methods to find the critical actuation parameters, such as strain distribution, maximum strain, and response time. One-dimensional results of the FEM solution are then extended to 2D to find the tip displacement of a flap actuator and experimentally verified. A model of a seven-degree-of-freedom biped robot, actuated by IPMC flaps, is then introduced. The possibility of fast and stable bipedal locomotion using IPMC artificial muscles is the main motivation of this study. Considering the actuator limits, joint path trajectories are generated to achieve a fast and smooth motion. The stability of the proposed gait is then evaluated using the ZMP criterion and motion simulation. The fabrication parameters of each actuator, such as length, platinum plating thickness and installation angle, are then determined using the generated trajectories. A discussion on future studies on force-torque generation of IPMCs for biped locomotion concludes this paper.

Maneuvers during legged locomotion

NASA Astrophysics Data System (ADS)

Jindrich, Devin L.; Qiao, Mu

2009-06-01

Maneuverability is essential for locomotion. For animals in the environment, maneuverability is directly related to survival. For humans, maneuvers such as turning are associated with increased risk for injury, either directly through tissue loading or indirectly through destabilization. Consequently, understanding the mechanics and motor control of maneuverability is a critical part of locomotion research. We briefly review the literature on maneuvering during locomotion with a focus on turning in bipeds. Walking turns can use one of several different strategies. Anticipation can be important to adjust kinematics and dynamics for smooth and stable maneuvers. During running, turns may be substantially constrained by the requirement for body orientation to match movement direction at the end of a turn. A simple mathematical model based on the requirement for rotation to match direction can describe leg forces used by bipeds (humans and ostriches). During running turns, both humans and ostriches control body rotation by generating fore-aft forces. However, whereas humans must generate large braking forces to prevent body over-rotation, ostriches do not. For ostriches, generating the lateral forces necessary to change movement direction results in appropriate body rotation. Although ostriches required smaller braking forces due in part to increased rotational inertia relative to body mass, other movement parameters also played a role. Turning performance resulted from the coordinated behavior of an integrated biomechanical system. Results from preliminary experiments on horizontal-plane stabilization support the hypothesis that controlling body rotation is an important aspect of stable maneuvers. In humans, body orientation relative to movement direction is rapidly stabilized during running turns within the minimum of two steps theoretically required to complete analogous maneuvers. During straight running and cutting turns, humans exhibit spring-mass behavior in the

The Enigmatic Longevity of Granular Materials on Mars: The Case for Geologically Episodic Dune Formation

NASA Technical Reports Server (NTRS)

Marshall, J.

1999-01-01

Martian sand dunes are concentrated in vast sand seas in the circumpolar belt of the planet's northern hemisphere, but they are also pervasive over the whole planet. Their occurrence is to be expected on a super-arid planetary surface subjected to boundary layer drag from a continually active atmosphere. Whilst their occurrence is to be expected, their survival is enigmatic. But the enigma only arises if the martian system is considered similar to Earth's --where sand is moved highly frequently, more or less on a seasonal basis. Experimentally it is readily demonstrated that active sand will soon wear down to small grains and eventually diminish to below the critical sand size required to sustain dune formation. According to conventional wisdom, sand moves at higher speeds on Mars than on Earth, and if it were to move as frequently as it does on Earth, then the dune-forming sand population should have long since disappeared, given the great longevity of the martian aeolian system (Sagan coined the term "kamikaze" grains to express this disappearance). No supply of sand could keep pace with this depletion, especially in light of the fact that Mars does not have very active weathering, nor significant crustal differentiation. On Earth, plate tectonics, magmatic activity, and general crustal differentiation over geological time have produced great concentrations of quartz crystals in the continental crustal masses. Not only are these quartz grains chemically and mechanically resilient, they are about the right size for being transported by either wind or water. Add to this, the geologically recent contribution of glacial grinding, and it is easy to see why there are dune field on Earth. So what are the martian dunes composed of, and how does the material survive the eons of attrition? In addition to experimental demonstrations of sand comminution in laboratory aeolian simulations, the problem can be approached from first principles. Sagan showed that by simple

Evaluating alternative gait strategies using evolutionary robotics

PubMed Central

Sellers, William I; Dennis, Louise A; Wang, W -J; Crompton, Robin H

2004-01-01

Evolutionary robotics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robot is predefined and various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requirements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance parameters such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictions for modern humans are highly accurate in terms of energy cost for a given speed and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human-like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominids. PMID:15198699

Determining the origin of enigmatic bedrock structures using apatite (U-Th)/He thermochronology: Alabama and Poverty Hills, Owens Valley, California

NASA Astrophysics Data System (ADS)

Ali, G. A.; Reiners, P. W.; Ducea, M.

2008-12-01

The Alabama and Poverty Hills are enigmatic, topographic highs of crystalline basement surrounded by Neogene sediments in Owens Valley, California. The 150-km long Owens Valley, the westernmost graben of the Basin and Range Province, initiated at about 3 Ma, creating ~2-4 km of vertical relief from the Sierra Nevada and White/Inyos crests to the valley floor. Along the valley, the active right-lateral Owens Valley Fault Zone (OVFZ) accommodates a significant portion of Pacific-North American plate motion, creating an oblique dextral fault zone, with localized transpression along minor left-stepovers. The dominantly granitic Mesozoic rocks of the Alabama Hills are bounded by the OVFZ to the east, and the granitic and metavolcanic Mesozoic rocks of the Poverty Hills are located along an apparent 3-km left stepover of the OVFZ. The tectonic origin and geodynamic significance of both these structures are not known, but previously published hypotheses include: 1) transpressional uplifts as OVFZ-related flower structures; 2) down-dropped normal fault blocks; and 3) giant landslides from adjacent ranges. We measured apatite (U-Th)/He ages on 15 samples from the Alabama and Poverty Hills to understand the history of shallow crustal exhumation of these structures, and to potentially correlate them to rocks from adjacent ranges. Apatite He dating typically yields cooling ages corresponding to closure temperatures of ~55-65 °C, corresponding roughly to depths of ~2-3 km in the crust. The majority of apatite He ages from the Alabama Hills ranged from 58-70 Ma, but the far eastern, and lowest elevation sample showed ages of 51-55 Ma. The Poverty Hills shows younger ages of 40-65 Ma and no recognizable spatial pattern. Although the data do not conclusively rule out a transpressional uplift origin of the Poverty Hills, the rocks within them could not have been exhumed from depths greater than ~2-3 km in Owens Valley. Data from both structures are most consistent with down

Cd(II)-coordination polymers based on tetracarboxylic acid and diverse bis(imidazole) ligands: Synthesis, structural diversity and photoluminescence properties

NASA Astrophysics Data System (ADS)

Arıcı, Mürsel; Yeşilel, Okan Zafer; Taş, Murat

2017-01-01

Three new Cd(II)-coordination polymers, namely, {[Cd2(μ6-ao2btc)(μ-1,5-bipe)2]·2H2O}n (1), {[Cd2(μ6-ao2btc)(μ-1,4-bix)2]n·2DMF} (2) and {[Cd2(μ8-abtc)(μ-1,4-betix)]·DMF·H2O}n (3) (ao2btc=di-oxygenated form of 3,3‧,5,5‧-azobenzenetetracarboxylate, 1,5-bipe: 1,5-bis(imidazol-1yl)pentane, 1,4-bix=1,4-bis(imidazol-1ylmethyl)benzene, 1,4-betix=1,4-bis(2-ethylimidazol-1ylmethyl)benzene) were synthesized with 3,3‧,5,5‧-azobenzenetetracarboxylic acid and flexible, semi-flexible and semi-flexible substituted bis(imidazole) linkers. They were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and thermal analyses (TG/DTA). Complexes 1-3 exhibited structural diversities depending on flexible, semi-flexible and semi-flexible substituted bis(imidazole) ligands. Complex 1 was 2D structure with 3,6L18 topology. Complex 2 had a 3D pillar-layered framework with the rare sqc27 topology. When semi-flexible substituted bis(imidazole) linker was used, 3D framework of complex 3 was obtained with the paddlewheel Cd2(CO2)4-type binuclear SBU. Moreover, thermal and photoluminescence properties of the complexes were determined in detailed.

The enigmatic Bala earthquake of 1974

NASA Astrophysics Data System (ADS)

Musson, R. M. W.

2006-10-01

The earthquake that shook most of North Wales on the night of 23 January 1974 appears unremarkable from its entry in the UK earthquake catalogue. With a magnitude of 3.5 ML it represents the size of earthquake to be expected in the UK with a return period of about one year. However, the prominent atmospheric lights observed at the time of the shock led to speculation that an aircraft had crashed, and search-and-rescue teams were deployed. Since nothing was discovered, it was concluded that a meteorite was responsible; more imaginative members of the public decided (and still believe) that a UFO had crashed. In this paper the record of events is set out, and the nature of the earthquake is discussed with reference to its geological setting.

The Enigmatic Face of the Moon

NASA Astrophysics Data System (ADS)

Galles, C. D.; Gallagher, C. J.

2011-06-01

Whilst Man's only way of observing the Moon was with the naked eye, attempts at explaining the spots on her surface remained highly speculative. The telescopic observation by Galileo of previously unknown spots, differing from the earlier ones by their variability in time, was to signify a radical change to the hereto medieval ideas on the material composition of the Moon. And curiously enough, this new scenario was a revindication of Plutarch's hypothesis construed more than a millennium before.

Archaeal viruses--novel, diverse and enigmatic.

PubMed

Peng, Xu; Garrett, Roger A; She, QunXin

2012-05-01

Recent research has revealed a remarkable diversity of viruses in archaeal-rich environments where spindles, spheres, filaments and rods are common, together with other exceptional morphotypes never recorded previously. Moreover, their double-stranded DNA genomes carry very few genes exhibiting homology to those of bacterial and eukaryal viruses. Studies on viral life cycles are still at a preliminary stage but important insights are being gained especially from microarray analyses of viral transcripts for a few model virus-host systems. Recently, evidence has been presented for some exceptional archaeal-specific mechanisms for extra-cellular morphological development of virions and for their cellular extrusion. Here we summarise some of the recent developments in this rapidly developing and exciting research area.

Burning mouth syndrome: an enigmatic disorder.

PubMed

Javali, M A

2013-01-01

Burning mouth syndrome (BMS) is a chronic oral pain or burning sensation affecting the oral mucosa, often unaccompanied by mucosal lesions or other evident clinical signs. It is observed principally in middle-aged patients and postmenopausal women and may be accompanied by xerostomia and altered taste. Burning mouth syndrome is characterized by an intense burning or stinging sensation, preferably on the tongue or in other areas of mouth. This disorder is one of the most common, encountered in the clinical practice. This condition is probably of multifactorial origin; however the exact underlying etiology remains uncertain. This article discusses several aspects of BMS, updates current knowledge about the etiopathogenesis and describes the clinical features as well as the diagnosis and management of BMS patients.

The Enigmatic Persistence of Anorexia Nervosa

PubMed Central

Walsh, B. Timothy

2014-01-01

Objective In this review, based on recent advances in cognitive neuroscience, the author presents a formulation in which the marked persistence of anorexia nervosa can be usefully understood as a well-ingrained maladaptive habit. Method The author reviewed the relevant literature on the development and course of anorexia nervosa and interpreted critical features in light of developments in cognitive neuroscience. Results Anorexia nervosa is a well characterized disorder with remarkable persistence both across history and among affected individuals. Food restriction, the salient behavioral feature of the disorder, often begins innocently but gradually takes on a life of its own. Over time, it becomes highly entrenched and resistant to change through either psychological or pharmacological treatment. Cognitive neuroscience has described two related but distinct processes that underlie the acquisition of new patterns of behavior, namely, action-outcome and stimulus-response learning. It is likely that both processes are engaged in the development of anorexia nervosa and that stimulus-response learning (that is, habit formation) is critical to the persistence of the dieting behavior. Conclusions The formulation of the dieting behavior characteristic of anorexia nervosa as a well-entrenched habit provides a basis for understanding the striking persistence of this disorder. This model helps explain the resistance of anorexia nervosa to interventions that have established efficacy in related disorders and implies that addressing the dieting behavior is critical, especially early in the course of the illness, before it has become ingrained. PMID:23429750

Walk-Startup of a Two-Legged Walking Mechanism

NASA Astrophysics Data System (ADS)

Babković, Kalman; Nagy, László; Krklješ, Damir; Borovac, Branislav

There is a growing interest towards humanoid robots. One of their most important characteristic is the two-legged motion - walk. Starting and stopping of humanoid robots introduce substantial delays. In this paper, the goal is to explore the possibility of using a short unbalanced state of the biped robot to quickly gain speed and achieve the steady state velocity during a period shorter than half of the single support phase. The proposed method is verified by simulation. Maintainig a steady state, balanced gait is not considered in this paper.

Revision of the Neotropical water scavenger beetle genus Tobochares Short & García, 2007 (Coleoptera, Hydrophilidae, Acidocerinae)

PubMed Central

Kohlenberg, Alex T.; Short, Andrew Edward Z.

2017-01-01

Abstract The genus Tobochares Short & García, 2007 is revised. A combination of morphological and molecular data provide support for ten distinct species. Five new species are described: T. canaliculatus sp. n. (Venezuela), T. canthus sp. n. (Venezuela), T. emarginatus sp. n. (Suriname), T. kusad sp. n. (Guyana), and T. pallidus sp. n. (Venezuela). All four preexisting species are redescribed. A tenth species, known from a single female from Venezuela, is left undescribed pending the collection of additional specimens. New collecting records are provided for T. sulcatus Short & García, 2007 and T. kasikasima Short, 2013. Tobochares sipaliwini Short & Kadosoe, 2011 is newly recorded from Guyana. All species are associated with seepage or wet rock habitats, although some species have also been found along the margins of streams that flow over rocky substrates. High-resolution images including scanning electron micrographs are provided, as well as a key to species and habitat photographs. PMID:28769656

Kinematics and dynamics analysis of a quadruped walking robot with parallel leg mechanism

NASA Astrophysics Data System (ADS)

Wang, Hongbo; Sang, Lingfeng; Hu, Xing; Zhang, Dianfan; Yu, Hongnian

2013-09-01

It is desired to require a walking robot for the elderly and the disabled to have large capacity, high stiffness, stability, etc. However, the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function. Therefore, Improvement of enhancing capacity and functions of the walking robot is an important research issue. According to walking requirements and combining modularization and reconfigurable ideas, a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed. The proposed robot can be used for both a biped and a quadruped walking robot. The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized. The results show that performance of the walking robot is optimal when the circumradius R, r of the upper and lower platform of leg mechanism are 161.7 mm, 57.7 mm, respectively. Based on the optimal results, the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory, and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed, which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process. Besides laying a theoretical foundation for development of the prototype, the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.

Children and adults minimise activated muscle volume by selecting gait parameters that balance gross mechanical power and work demands.

PubMed

Hubel, Tatjana Y; Usherwood, James R

2015-09-01

Terrestrial locomotion on legs is energetically expensive. Compared with cycling, or with locomotion in swimming or flying animals, walking and running are highly uneconomical. Legged gaits that minimise mechanical work have previously been identified and broadly match walking and running at appropriate speeds. Furthermore, the 'cost of muscle force' approaches are effective in relating locomotion kinetics to metabolic cost. However, few accounts have been made for why animals deviate from either work-minimising or muscle-force-minimising strategies. Also, there is no current mechanistic account for the scaling of locomotion kinetics with animal size and speed. Here, we report measurements of ground reaction forces in walking children and adult humans, and their stance durations during running. We find that many aspects of gait kinetics and kinematics scale with speed and size in a manner that is consistent with minimising muscle activation required for the more demanding between mechanical work and power: spreading the duration of muscle action reduces activation requirements for power, at the cost of greater work demands. Mechanical work is relatively more demanding for larger bipeds--adult humans--accounting for their symmetrical M-shaped vertical force traces in walking, and relatively brief stance durations in running compared with smaller bipeds--children. The gaits of small children, and the greater deviation of their mechanics from work-minimising strategies, may be understood as appropriate for their scale, not merely as immature, incompletely developed and energetically sub-optimal versions of adult gaits. © 2015. Published by The Company of Biologists Ltd.

Phylogenetic relationships among amphisbaenian reptiles based on complete mitochondrial genomic sequences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macey, J. Robert; Papenfuss, Theodore J.; Kuehl, Jennifer V.

2004-05-19

Complete mitochondrial genomic sequences are reported from 12 members in the four families of the reptile group Amphisbaenia. Analysis of 11,946 aligned nucleotide positions (5,797 informative) produces a robust phylogenetic hypothesis. The family Rhineuridae is basal and Bipedidae is the sister taxon to the Amphisbaenidae plus Trogonophidae. Amphisbaenian reptiles are surprisingly old, predating the breakup of Pangaea 200 million years before present, because successive basal taxa (Rhineuridae and Bipedidae) are situated in tectonic regions of Laurasia and nested taxa (Amphisbaenidae and Trogonophidae) are found in Gondwanan regions. Thorough sampling within the Bipedidae shows that it is not tectonic movement ofmore » Baja California away from the Mexican mainland that is primary in isolating Bipes species, but rather that primary vicariance occurred between northern and southern groups. Amphisbaenian families show parallel reduction in number of limbs and Bipes species exhibit parallel reduction in number of digits. A measure is developed for comparing the phylogenetic information content of various genes. A synapomorphic trait defining the Bipedidae is a shift from the typical vertebrate mitochondrial gene arrangement to the derived state of trnE and nad6. In addition, a tandem duplication of trnT and trnP is observed in B. biporus with a pattern of pseudogene formation that varies among populations. The first case of convergent rearrangement of the mitochondrial genome among animals demonstrated by complete genomic sequences is reported. Relative to most vertebrates, the Rhineuridae has the block nad6, trnE switched in order with cob, trnT, trnP, as they are in birds.« less

Advances in understanding ventromedial prefrontal function: the accountant joins the executive.

PubMed

Fellows, Lesley K

2007-03-27

Studies of the brain basis of decision-making and economic behavior are providing a new perspective on the organization and functions of human prefrontal cortex. This line of inquiry has focused particularly on the ventral and medial portions of prefrontal cortex, arguably the most enigmatic regions of the "enigmatic frontal lobes." This review highlights recent advances in the cognitive neuroscience of decision making and neuroeconomics and discusses how these findings can inform clinical thinking about frontal lobe dysfunction.

Stereo vision with distance and gradient recognition

NASA Astrophysics Data System (ADS)

Kim, Soo-Hyun; Kang, Suk-Bum; Yang, Tae-Kyu

2007-12-01

Robot vision technology is needed for the stable walking, object recognition and the movement to the target spot. By some sensors which use infrared rays and ultrasonic, robot can overcome the urgent state or dangerous time. But stereo vision of three dimensional space would make robot have powerful artificial intelligence. In this paper we consider about the stereo vision for stable and correct movement of a biped robot. When a robot confront with an inclination plane or steps, particular algorithms are needed to go on without failure. This study developed the recognition algorithm of distance and gradient of environment by stereo matching process.

Aromatic, Alphatic, Enigmatic: The Chemistry of Titan

NASA Astrophysics Data System (ADS)

Horst, Sarah

2017-10-01

The extraordinary complexity of Titan’s atmospheric chemistry far surpasses that of any other solar system atmosphere. With its thick N2 atmosphere and stable bodies of liquid on its surface, Titan also possesses many physical processes that are similar to those that occur on Earth. The connection between Titan’s surface and atmosphere is unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan’s atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan’s atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. I will review our current understanding of chemistry on Titan forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I will conclude with some of the questions that remain after Cassini-Huygens.

The Enigmatic Origin of Papillomavirus Protein Domains

PubMed Central

Kirsip, Heleri; Gaston, Kevin

2017-01-01

Almost a century has passed since the discovery of papillomaviruses. A few decades of research have given a wealth of information on the molecular biology of papillomaviruses. Several excellent studies have been performed looking at the long- and short-term evolution of these viruses. However, when and how papillomaviruses originate is still a mystery. In this study, we systematically searched the (sequenced) biosphere to find distant homologs of papillomaviral protein domains. Our data show that, even including structural information, which allows us to find deeper evolutionary relationships compared to sequence-only based methods, only half of the protein domains in papillomaviruses have relatives in the rest of the biosphere. We show that the major capsid protein L1 and the replication protein E1 have relatives in several viral families, sharing three protein domains with Polyomaviridae and Parvoviridae. However, only the E1 replication protein has connections with cellular organisms. Most likely, the papillomavirus ancestor is of marine origin, a biotope that is not very well sequenced at the present time. Nevertheless, there is no evidence as to how papillomaviruses originated and how they became vertebrate and epithelium specific. PMID:28832519

The Enigmatic Origin of Papillomavirus Protein Domains.

PubMed

Puustusmaa, Mikk; Kirsip, Heleri; Gaston, Kevin; Abroi, Aare

2017-08-23

Almost a century has passed since the discovery of papillomaviruses. A few decades of research have given a wealth of information on the molecular biology of papillomaviruses. Several excellent studies have been performed looking at the long- and short-term evolution of these viruses. However, when and how papillomaviruses originate is still a mystery. In this study, we systematically searched the (sequenced) biosphere to find distant homologs of papillomaviral protein domains. Our data show that, even including structural information, which allows us to find deeper evolutionary relationships compared to sequence-only based methods, only half of the protein domains in papillomaviruses have relatives in the rest of the biosphere. We show that the major capsid protein L1 and the replication protein E1 have relatives in several viral families, sharing three protein domains with Polyomaviridae and Parvoviridae . However, only the E1 replication protein has connections with cellular organisms. Most likely, the papillomavirus ancestor is of marine origin, a biotope that is not very well sequenced at the present time. Nevertheless, there is no evidence as to how papillomaviruses originated and how they became vertebrate and epithelium specific.

The Ellsworth Mountains: critical and enduringly enigmatic

USGS Publications Warehouse

Dalziel, I.W.D.

2007-01-01

The elevation (~5000m) is high for an early Mesozoic fold belt. Thermal uplift could have been initiated during Jurassic-Cretaceous block rotation and Weddell Sea opening and continued into the Cenozoic. The history of glaciation provides input for models of ice loading and unloading. Measurements of present-day uplift test these models and help assess change in the mass of the ice sheet and hence in global sea level.

Reinforcement learning: Solving two case studies

NASA Astrophysics Data System (ADS)

Duarte, Ana Filipa; Silva, Pedro; dos Santos, Cristina Peixoto

2012-09-01

Reinforcement Learning algorithms offer interesting features for the control of autonomous systems, such as the ability to learn from direct interaction with the environment, and the use of a simple reward signalas opposed to the input-outputs pairsused in classic supervised learning. The reward signal indicates the success of failure of the actions executed by the agent in the environment. In this work, are described RL algorithmsapplied to two case studies: the Crawler robot and the widely known inverted pendulum. We explore RL capabilities to autonomously learn a basic locomotion pattern in the Crawler, andapproach the balancing problem of biped locomotion using the inverted pendulum.

Does bipedality predict the group-level manual laterality in mammals?

PubMed

Giljov, Andrey; Karenina, Karina; Malashichev, Yegor

2012-01-01

Factors determining patterns of laterality manifestation in mammals remain unclear. In primates, the upright posture favours the expression of manual laterality across species, but may have little influence within a species. Whether the bipedalism acts the same in non-primate mammals is unknown. Our recent findings in bipedal and quadrupedal marsupials suggested that differences in laterality pattern, as well as emergence of manual specialization in evolution might depend on species-specific body posture. Here, we evaluated the hypothesis that the postural characteristics are the key variable shaping the manual laterality expression across mammalian species. We studied forelimb preferences in a most bipedal marsupial, brush-tailed bettong, Bettongia penicillata in four different types of unimanual behavior. The significant left-forelimb preference at the group level was found in all behaviours studied. In unimanual feeding on non-living food, catching live prey and nest-material collecting, all or most subjects were lateralized, and among lateralized bettongs a significant majority displayed left-forelimb bias. Only in unimanual supporting of the body in the tripedal stance the distribution of lateralized and non-lateralized individuals did not differ from chance. Individual preferences were consistent across all types of behaviour. The direction or the strength of forelimb preferences were not affected by the animals' sex. Our findings support the hypothesis that the expression of manual laterality depends on the species-typical postural habit. The interspecies comparison illustrates that in marsupials the increase of bipedality corresponds with the increase of the degree of group-level forelimb preference in a species. Thus, bipedalism can predict pronounced manual laterality at both intra- and interspecific levels in mammals. We also conclude that quadrupedal position in biped species can slightly hinder the expression of manual laterality, but the evoked biped

A Control Framework for Anthropomorphic Biped Walking Based on Stabilizing Feedforward Trajectories.

PubMed

Rezazadeh, Siavash; Gregg, Robert D

2016-10-01

Although dynamic walking methods have had notable successes in control of bipedal robots in the recent years, still most of the humanoid robots rely on quasi-static Zero Moment Point controllers. This work is an attempt to design a highly stable controller for dynamic walking of a human-like model which can be used both for control of humanoid robots and prosthetic legs. The method is based on using time-based trajectories that can induce a highly stable limit cycle to the bipedal robot. The time-based nature of the controller motivates its use to entrain a model of an amputee walking, which can potentially lead to a better coordination of the interaction between the prosthesis and the human. The simulations demonstrate the stability of the controller and its robustness against external perturbations.

The basic mechanics of bipedal walking lead to asymmetric behavior.

PubMed

Gregg, Robert D; Degani, Amir; Dhaher, Yasin; Lynch, Kevin M

2011-01-01

This paper computationally investigates whether gait asymmetries can be attributed in part to basic bipedal mechanics independent of motor control. Using a symmetrical rigid-body model known as the compass-gait biped, we show that changes in environmental or physiological parameters can facilitate asymmetry in gait kinetics at fast walking speeds. In the environmental case, the asymmetric family of high-speed gaits is in fact more stable than the symmetric family of low-speed gaits. These simulations suggest that lower extremity mechanics might play a direct role in functional and pathological asymmetries reported in human walking, where velocity may be a common variable in the emergence and growth of asymmetry. © 2011 IEEE

Agile and dexterous robot for inspection and EOD operations

NASA Astrophysics Data System (ADS)

Handelman, David A.; Franken, Gordon H.; Komsuoglu, Haldun

2010-04-01

The All-Terrain Biped (ATB) robot is an unmanned ground vehicle with arms, legs and wheels designed to drive, crawl, walk and manipulate objects for inspection and explosive ordnance disposal tasks. This paper summarizes on-going development of the ATB platform. Control technology for semi-autonomous legged mobility and dual-arm dexterity is described as well as preliminary simulation and hardware test results. Performance goals include driving on flat terrain, crawling on steep terrain, walking on stairs, opening doors and grasping objects. Anticipated benefits of the adaptive mobility and dexterity of the ATB platform include increased robot agility and autonomy for EOD operations, reduced operator workload and reduced operator training and skill requirements.

Hominins without fellow travellers? First appearances and inferred dispersals of Afro-Eurasian large-mammals in the Plio-Pleistocene

NASA Astrophysics Data System (ADS)

O'Regan, H. J.; Turner, A.; Bishop, L. C.; Elton, S.; Lamb, A. L.

2011-06-01

Discoveries of fossil Homo outside Africa predating 1.0 Ma have generated much discussion about hominin dispersal routes. However, tool-using bipeds were only one element of the inter-continental mammalian dispersals that occurred during the climatic changes of the Pliocene and Pleistocene. This paper will place hominin movements in the context of those of the wider mammalian fauna, which includes carnivores, bovids and non-human primates. The distribution of these different taxa suggests that species moved individually when the environmental conditions were right for them, rather than in multi-species waves of dispersal, and allows evaluation of the contextual evidence for the newly emerging 'Out of Asia' paradigm as well as the established 'Out of Africa' model.

The origins of the enigmatic Falkland Islands wolf.

PubMed

Austin, Jeremy J; Soubrier, Julien; Prevosti, Francisco J; Prates, Luciano; Trejo, Valentina; Mena, Francisco; Cooper, Alan

2013-01-01

The origins of the extinct Falkland Islands wolf (FIW), Dusicyon australis, have remained a mystery since it was first recorded by Europeans in the seventeenth century. It is the only terrestrial mammal on the Falkland Islands (also known as the Malvinas Islands), which lie ~460 km from Argentina, leading to suggestions of either human-mediated transport or overwater dispersal. Previous studies used ancient DNA from museum specimens to suggest that the FIW diverged from its closest living relative, the South American maned wolf (Chrysocyon brachyurus) around 7 Ma, and colonized the islands ~330 ka by unknown means. Here we retrieve ancient DNA from subfossils of an extinct mainland relative, Dusicyon avus, and reveal the FIW lineage became isolated only 16 ka (8-31 ka), during the last glacial phase. Submarine terraces, formed on the Argentine coastal shelf by low sea-stands during this period, suggest that the FIW colonized via a narrow, shallow marine strait, potentially while it was frozen over.

Raman spectroscopic analysis of the enigmatic Comper pigments.

PubMed

Edwards, Howell G M; Wolstenholme, Rosalind; Wilkinson, David S; Brooke, Christopher; Pepper, Michelle

2007-03-01

An early church decoration project carried out by Sir Ninian Comper in 1896-98, involving the rood screen and canopy in St. Mary's, Egmanton, is currently undergoing restoration. Despite the rather prolific works of this famous ecclesiastical architect, there is little information available about the actual pigments that he used in his projects that gave rise to the special nomenclature "Comper green" and "Comper red". Specimens of green, red, black, grey, white and blue paint from this work have been made available for Raman spectroscopic analysis, and their identification has been achieved for the first time. The characteristic red and green pigments used in Comper's work, Comper green and Comper red, are both seen to be mixtures; in the former, Raman bands from chrome yellow (lead(II) chromate) and Prussian blue are identified, and the latter is confirmed as being a mixture of vermilion (mercury(II) sulfide) and barytes (barium sulfate). The other colours are found to represent a rich diversity of palette and include haematite, lead tin yellow (type II), lamp black, gypsum, anhydrite, hydrocerussite and calcite. The information from this first Raman spectroscopic study of Comper's palette will assist the conservation and restoration of an important nineteenth century church decoration.

The enigmatic star EZ Pegasi - A mystery solved?

NASA Technical Reports Server (NTRS)

Howell, S. B.; Bopp, B. W.

1985-01-01

EZ Peg, a ninth-magnitude G star that has been classified by various authors as an irregular variable, a U Gem system, and a contact binary, is shown to have all the spectroscopic and photometric characteristics of an active-chromosphere RS CVn binary. It is suggested that the reported outburst of 1943, when the spectrum appeared to be that of a B star, never occurred. The strong Ca II H and K reversals, viewed with low spectral resolution, caused the photospheric Ca II absorption to appear abnormally weak, mimicking a much earlier spectral type.

Bacterial morphogenesis and the enigmatic MreB helix.

PubMed

Errington, Jeff

2015-04-01

Work over the past decade has highlighted the pivotal role of the actin-like MreB family of proteins in the determination and maintenance of rod cell shape in bacteria. Early images of MreB localization revealed long helical filaments, which were suggestive of a direct role in governing cell wall architecture. However, several more recent, higher-resolution studies have questioned the existence or importance of the helical structures. In this Opinion article, I navigate a path through these conflicting reports, revive the helix model and summarize the key questions that remain to be answered.

Enigmatic Qualities of the Gifted That Transcend Identification

ERIC Educational Resources Information Center

Phelps, Connie

2012-01-01

In "A Quality of Giftedness," Professor Joan Freeman reflects upon her long career working as a psychologist in England with gifted children. She gives particular attention to observations gained during the most recent analysis of her longitudinal study that was published in 2010 as Gifted Lives. This work provides an in-depth look at 20…

The Enigmatic Savior of the Union: Abraham Lincoln.

ERIC Educational Resources Information Center

Diamond, Ronald L.; Diamond, Linda W.

Abraham Lincoln rose from the depths of obscurity to guide the United States successfully through the turbulent and menacing years of the Civil War. Laborer, businessman, postmaster, politician, and lawyer were some of the vocations, not all successful, that Lincoln tried during the years leading to his ascent to the Presidency. This review of the…

Ruddy Freckles on Europa

NASA Image and Video Library

2002-10-30

Reddish spots and shallow pits pepper the enigmatic ridged surface of Europa in this view combining information from images taken by NASA Galileo spacecraft during two different orbits around Jupiter.

Lightning in the Protoplanetary Nebula?

NASA Technical Reports Server (NTRS)

Love, Stanley G.

1997-01-01

Lightning in the protoplanetary nebula has been proposed as a mechanism for creating meteoritic chondrules: enigmatic mm-sized silicate spheres formed in the nebula by the brief melting of cold precursors.

Nilosyrtis Mensae

NASA Image and Video Library

2003-01-30

The floors of these craters imaged by NASA Mars Odyssey contain very interesting and enigmatic materials that may hold shallow subsurface ground ice with varying amounts of a sediment covering mantle.

Does Bipedality Predict the Group-Level Manual Laterality in Mammals?

PubMed Central

Giljov, Andrey; Karenina, Karina; Malashichev, Yegor

2012-01-01

Background Factors determining patterns of laterality manifestation in mammals remain unclear. In primates, the upright posture favours the expression of manual laterality across species, but may have little influence within a species. Whether the bipedalism acts the same in non-primate mammals is unknown. Our recent findings in bipedal and quadrupedal marsupials suggested that differences in laterality pattern, as well as emergence of manual specialization in evolution might depend on species-specific body posture. Here, we evaluated the hypothesis that the postural characteristics are the key variable shaping the manual laterality expression across mammalian species. Methodology/Principal Findings We studied forelimb preferences in a most bipedal marsupial, brush-tailed bettong, Bettongia penicillata in four different types of unimanual behavior. The significant left-forelimb preference at the group level was found in all behaviours studied. In unimanual feeding on non-living food, catching live prey and nest-material collecting, all or most subjects were lateralized, and among lateralized bettongs a significant majority displayed left-forelimb bias. Only in unimanual supporting of the body in the tripedal stance the distribution of lateralized and non-lateralized individuals did not differ from chance. Individual preferences were consistent across all types of behaviour. The direction or the strength of forelimb preferences were not affected by the animals’ sex. Conclusions/Significance Our findings support the hypothesis that the expression of manual laterality depends on the species-typical postural habit. The interspecies comparison illustrates that in marsupials the increase of bipedality corresponds with the increase of the degree of group-level forelimb preference in a species. Thus, bipedalism can predict pronounced manual laterality at both intra- and interspecific levels in mammals. We also conclude that quadrupedal position in biped species can

``Hiss, clicks and pops'' - The enigmatic sounds of meteors

NASA Astrophysics Data System (ADS)

Finnegan, J. A.

2015-04-01

The improbability of sounds heard simultaneously with meteors allows the phenomenon to remain on the margins of scientific interest and research. This is unjustified, since these audibly perceived electric field effects indicate complex, inconsistent and still unresolved electric-magnetic coupling and charge dynamics; interacting between the meteor; the ionosphere and mesosphere; stratosphere; troposphere and the surface of the earth. This paper reviews meteor acoustic effects, presents illustrating reports and hypotheses and includes a summary of similar and additional phenomena observed during the 2013 February 15 asteroid fragment disintegration above the Russian district of Chelyabinsk. An augmenting theory involving near ground, non uniform electric field production of Ozone, as a stimulated geo-physical phenomenon to explain some hissing `meteor sounds' is suggested in section 2.2. Unlike previous theories, electric-magnetic field fluctuation rates are not required to occur in the audio frequency range for this process to acoustically emit hissing and intermittent impulsive sounds; removing the requirements of direct conversion, passive human transduction or excited, localised acoustic `emitters'. Links to the Armagh Observatory All-sky meteor cameras, electrophonic meteor research and full construction plans for an extremely low frequency (ELF) receiver are also included.

The larval abdomen of the enigmatic Nannochoristidae (Mecoptera, Insecta).

PubMed

Fraulob, Maximilian; Wipfler, Benjamin; Hünefeld, Frank; Pohl, Hans; Beutel, Rolf G

2012-03-01

External and internal structures of the larval abdomen of Nannochorista are described in detail, with emphasis on the posterior segments. The results are compared with conditions found in other groups of Antliophora, especially the mecopteran subgroups Boreidae and Pistillifera. Like the entire postcephalic body, the larval abdomen of Nannochorista is extremely slender and nearly cylindrical. The anterior segments are largely unmodified. The surface is smooth and lacks any protuberances or prolegs. The term "cloaca" for the posterior membranous pouch of Nannochorista sp. is morphologically unjustified. A list of muscles of segments IX and X is presented. The abdominal musculature was partly homologized following Snodgrass. The muscles of segment X are highly modified. They move the membranous pouch, the anal papillae, and the terminal lobes. The presence of these structures is likely an adaptation to the specific aquatic life style of nannochoristid larvae. The anal papillae are possibly homologous to the 4-lobed terminal attachment apparatus of larvae of Caurinus (Boreidae) and Pistillifera (Panorpidae, Bittacidae, Choristidae) but this is uncertain. The specific condition in both groups, i.e. two retractile papillae with tracheae and Malpighian tubules in Nannochoristidae, and a 4-lobed exposed attachment device in Pistillifera + Boreidae (groundplan) are very likely autapomorphic for both groups, respectively. A slender abdomen with smooth surface is very likely plesiomorphic within Antliophora and Mecopterida. This condition is found in Trichoptera (partim), Nannochoristidae, Siphonaptera, and many basal groups of Diptera. An eruciform or scarabaeiform body shape with a soft, largely unsclerotised cuticle is probably a synapomorphy of Boreidae and Pistillifera. The presence of ventral protuberances resembling prolegs on the anterior segments is an autapomorphy of the latter group. The homology of paired or unpaired terminal appendages of segment X is uncertain. However, the specific condition of paired and 3-segmented appendages with hooks in Nannochoristidae is almost certainly autapomorphic for this family. The protracted opening of the hind gut on the membranous pouch is another potential autapomorphy of Nannochoristidae. Aquatic habits of larvae, also very likely an apomorphic condition, have likely evolved several times independently in Antliophora. Copyright © 2011 Elsevier Ltd. All rights reserved.

Detection of an enigmatic plethodontid Salamander using Environmental DNA

USGS Publications Warehouse

Pierson, Todd W.; Mckee, Anna; Spear, Stephen F.; Maerz, John C.; Camp, Carlos D.; Glenn, Travis C.

2016-01-01

The isolation and identification of environmental DNA (eDNA) offers a non-invasive and efficient method for the detection of rare and secretive aquatic wildlife, and it is being widely integrated into inventory and monitoring efforts. The Patch-Nosed Salamander (Urspelerpes brucei) is a tiny, recently discovered species of plethodontid salamander known only from headwater streams in a small region of Georgia and South Carolina. Here, we present results of a quantitative PCR-based eDNA assay capable of detecting Urspelerpes in more than 75% of 33 samples from five confirmed streams. We deployed the method at 31 additional streams and located three previously undocumented populations of Urspelerpes. We compare the results of our eDNA assay with our attempt to use aquatic leaf litterbags for the rapid detection of Urspelerpes and demonstrate the relative efficacy of the eDNA assay. We suggest that eDNA offers great potential for use in detecting other aquatic and semi-aquatic plethodontid salamanders.

Do the enigmatic ``Infrared-Faint Radio Sources'' include pulsars?

NASA Astrophysics Data System (ADS)

Hobbs, George; Middelberg, Enno; Norris, Ray; Keith, Michael; Mao, Minnie; Champion, David

2009-04-01

The Australia Telescope Large Area Survey (ATLAS) team have surveyed seven square degrees of sky at 1.4GHz. During processing some unexpected infrared-faint radio sources (IFRS sources) were discovered. The nature of these sources is not understood, but it is possible that some of these sources may be pulsars within our own galaxy. We propose to observe the IFRS sources with steep spectral indices using standard search techniques to determine whether or not they are pulsars. A pulsar detection would 1) remove a subset of the IFRS sources from the ATLAS sample so they would not need to be observed with large optical/IR telescopes to find their hosts and 2) be intrinsically interesting as the pulsar would be a millisecond pulsar and/or have an extreme spatial velocity.

Thy-1, the enigmatic extrovert on the neuronal surface.

PubMed

Morris, R

1992-10-01

Thy-1 is a small glycoprotein of 110 amino acids which, folded in the characteristic structure of an immunoglobulin variable domain, are enchored to the plasma membrane via a glycophosphatidylinositol (GPI) tail (Fig. 1). It is a major component of the surface of various cell types, including neurons, at certain stages of their development. These qualities doubtlessly appeal to certain cognoscenti, but it is not clear why they would raise Thy-1 to the status of a favourite molecule. Indeed, few scientists readily admit to having a favourite. We study individual molecules because science is rooted in specific observations; but we do so in order to discover mechanisms of general importance. A molecule's appeal is dependent on its ability to reveal novel aspects of how nature works. Thy-1 has been unusual in this respect. It was the first lymphocyte surface antigen shown to be restricted to a functional subset of lymphocytes (T cells in the mouse), a finding crucial to the development of cellular immunology; it was one of the first cell surface molecules to be sequenced and indicated the importance of immunoglobulin domains and GPI anchors as structural motifs; it has been pivotal in studies demonstrating that GPI-anchored molecules are able to signal across the membrane they do not span. Thy-1 has revealed this much, however, with the charm of an adroit stripper: it has always promised glimpses of things more exciting than that displayed. In particular, the function of this molecule has never emerged.(ABSTRACT TRUNCATED AT 250 WORDS)

XTE J1946+274: An Enigmatic X-Ray Pulsar

NASA Technical Reports Server (NTRS)

Wilson, Colleen A.; Finger, Mark H.; Coe, M. J.; Negueruela, Ignacio; Six, N. Frank (Technical Monitor)

2002-01-01

XTE J1946+274 = GRO J1944+26 is a 15.8-s X-ray pulsar discovered simultaneously by the Rossi X-ray Timing Explorer (RXTE) and the Burst and Transient Source Experiment (BATSE) in September 1998. Follow-up optical/IR observations resulted in the discovery of a Be star companion. Our pulse timing analysis of BATSE and RXTE data indicates that the orbital period is approximately 169 days. Since its discovery in 1998, XTE J1946+274 has undergone 13 outbursts. These outbursts axe not regularly spaced. They occur approximately twice per orbit and are not locked in orbital phase, unlike most Be/X-ray transient systems. A possible explanation for this is a global-one armed oscillation or density perturbation propagating rapidly in the Be star's disk. We will investigate radial velocity variations in the central peak of the H-alpha line to look for evidence of such a perturbation. From 2001 March-September, we regularly monitored XTE J1946+274 with the RXTE PCA. We will demonstrate that the spectrum appears to be varying with orbital phase, based on the 2001 and 1998 RXTE PCA observations. We will also present histories of pulsed frequency and flux.

The enigmatic figure of Dr Henry Maudsley (1835-1918).

PubMed

Pantelidou, Maria; Demetriades, Andreas K

2014-08-01

In spite of his contribution to psychiatry in 19th century Britain, Henry Maudsley remains a mysterious figure, a man mostly known for his donation to the London County Council for the building of the Maudsley Hospital and for The Maudsley Annual Lecture created in honour of his benevolence. Besides Sir Aubrey Lewis' article in 1951 and Michael Collie's attempt in 1988 to construct a biographical study on Maudsley, there does not seem to be any current endeavour to tell the story of his life, whereas Trevor Turner's contribution to the 2004 Oxford Dictionary of National Biography gives a somewhat scathing but unattributed account of Maudsley's personality. This essay attempts to explore his contributions to the Medico-Psychological Association (MPA), the current Royal College of Psychiatrists, his editorship of the Journal of Mental Health (currently named the British Journal of Psychiatry), his literary contributions and his vision for a psychiatric hospital. This essay is an attempt to demystify his figure and to explore some of the rumours and criticisms surrounding his name and the reasons why so little has been written about him. It is also a venture to unravel his complex personality and his intricate philosophy. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

An Enigmatic Carbonate Layer in Everglades Tree Island Peats

NASA Astrophysics Data System (ADS)

Graf, Maria-Theresia; Schwadron, Margo; Stone, Peter A.; Ross, Michael; Chmura, Gail L.

2008-03-01

Recent archaeological excavations on the heads (i.e., the most elevated and upstream parts) of several large Everglades fixed tree islands may reshape what is understood about the age and formation of these landforms, and about the role of humans in the early Everglades wetland, between 3500 and 1000 B.C. Tree islands are patches of high ground, dry enough to support trees, that rise about 1 meter above the surrounding wetland, and those islands termed "fixed" are the large teardrop-shaped islands thought to have formed over localized high points in the underlying bedrock (Figures 1a and 1b). A hard, cemented carbonate layer perched in the sediments of two tree islands in the southern Everglades was discovered by U.S. National Park Service archaeologists, and penetration of it with a concrete saw revealed that beneath the layer are unconsolidated sediments containing archaeological artifacts dating back to late-Archaic times (3000-1000 B.C.) [Schwadron, 2006].

Enigmatic photon absorption in plasmas near solar interior conditions

NASA Astrophysics Data System (ADS)

Iglesias, Carlos A.

2015-06-01

Large systematic discrepancies between theoretical and experimental photon absorption of Fe plasmas applicable to the solar interior were reported [Bailey et al., Nature 517, 56 (2015)]. The disagreement is examined in the context of the Thomas-Reiche-Kuhn f-sum rule. The analysis identifies several anomalies in the experimental results.

The evolution of dinosaurs.

PubMed

Sereno, P C

1999-06-25

The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the Cretaceous. The dinosaurian radiation, launched by 1-meter-long bipeds, was slower in tempo and more restricted in adaptive scope than that of therian mammals. A notable exception was the evolution of birds from small-bodied predatory dinosaurs, which involved a dramatic decrease in body size. Recurring phylogenetic trends among dinosaurs include, to the contrary, increase in body size. There is no evidence for co-evolution between predators and prey or between herbivores and flowering plants. As the major land masses drifted apart, dinosaurian biogeography was molded more by regional extinction and intercontinental dispersal than by the breakup sequence of Pangaea.

Modeling of R/C Servo Motor and Application to Underactuated Mechanical Systems

NASA Astrophysics Data System (ADS)

Ishikawa, Masato; Kitayoshi, Ryohei; Wada, Takashi; Maruta, Ichiro; Sugie, Toshiharu

An R/C servo motor is a compact package of a DC geard-motor associated with a position servo controller. They are widely used in small-sized robotics and mechatronics by virtue of their compactness, easiness-to-use and high/weight ratio. However, it is crucial to clarify their internal model (including the embedded position servo) in order to improve control performance of mechatronic systems using R/C servo motors, such as biped robots or underactuted sysyems. In this paper, we propose a simple and realistic internal model of the R/C servo motors including the embedded servo controller, and estimate their physical parameters using continuous-time system identification method. We also provide a model of reference-to-torque transfer function so that we can estimate the internal torque acting on the load.

Getting a grip on systems of care and child welfare using opposable thumbs.

PubMed

Fluke, John D; Oppenheim, Elizabeth

2010-02-01

The purpose of this response paper is to discuss issues raised by two of the components of the definition of systems of care proffered by Hodges et al. [Hodges, S., Ferreira, K., Israel, N., & Mazza, J. (this issue). Systems of care, featherless bipeds, and the measure of all things. Evaluation and Program Planning]. In particular, this response will present some implications of the definition of the focus population and the value and core principle of family-driven care. It will also consider why these two components of the definition might serve as challenges to the applicability of the concept of systems of care to child welfare, and, in turn, integration of the model across child welfare and mental health. Recommendations for expanding and refining these component terms are provided.

Experimental Study of Hollow Formation

NASA Astrophysics Data System (ADS)

Parman, S. W.; Orlando, T. M.; Milliken, R. E.; Head, J. W.; Jones, B. M.; Anzures, B. A.

2018-05-01

Hollows are enigmatic features on the surface of Mercury caused by sublimation and/or space weathering. Here we propose a comprehensive experimental study in which candidate hollows materials are exposed to a range of relevant conditions.

Reward from bugs to bipeds: a comparative approach to understanding how reward circuits function

PubMed Central

Scaplen, Kristin M.; Kaun, Karla R.

2016-01-01

Abstract In a complex environment, animals learn from their responses to stimuli and events. Appropriate response to reward and punishment can promote survival, reproduction and increase evolutionary fitness. Interestingly, the neural processes underlying these responses are remarkably similar across phyla. In all species, dopamine is central to encoding reward and directing motivated behaviors, however, a comprehensive understanding of how circuits encode reward and direct motivated behaviors is still lacking. In part, this is a result of the sheer diversity of neurons, the heterogeneity of their responses and the complexity of neural circuits within which they are found. We argue that general features of reward circuitry are common across model organisms, and thus principles learned from invertebrate model organisms can inform research across species. In particular, we discuss circuit motifs that appear to be functionally equivalent from flies to primates. We argue that a comparative approach to studying and understanding reward circuit function provides a more comprehensive understanding of reward circuitry, and informs disorders that affect the brain’s reward circuitry. PMID:27328845

Development of a neuromorphic control system for a lightweight humanoid robot

NASA Astrophysics Data System (ADS)

Folgheraiter, Michele; Keldibek, Amina; Aubakir, Bauyrzhan; Salakchinov, Shyngys; Gini, Giuseppina; Mauro Franchi, Alessio; Bana, Matteo

2017-03-01

A neuromorphic control system for a lightweight middle size humanoid biped robot built using 3D printing techniques is proposed. The control architecture consists of different modules capable to learn and autonomously reproduce complex periodic trajectories. Each module is represented by a chaotic Recurrent Neural Network (RNN) with a core of dynamic neurons randomly and sparsely connected with fixed synapses. A set of read-out units with adaptable synapses realize a linear combination of the neurons output in order to reproduce the target signals. Different experiments were conducted to find out the optimal initialization for the RNN’s parameters. From simulation results, using normalized signals obtained from the robot model, it was proven that all the instances of the control module can learn and reproduce the target trajectories with an average RMS error of 1.63 and variance 0.74.

Bee cups: Single-use cages for honey bee experiments

USDA-ARS?s Scientific Manuscript database

Honey bees face challenges ranging from poor nutrition to exposure to parasites, pathogens, and environmental chemicals. These challenges drain colony resources and have been tied to both subtle and extreme colony declines, including the enigmatic Colony Collapse Disorder (CCD). Understanding how ...

Vitilevumyia, an enigmatic new genus of Stratiomyidae from Fiji (Diptera)

USDA-ARS?s Scientific Manuscript database

A new genus of Stratiomyidae, Vitilevumyia gen. nov. (type species, V. bobwoodleyi, sp. nov.) is described from the island of Viti Levu, Fiji. It exhibits an unusual combination of character states, but is tentatively placed in the tribe Prosopochrysini of the subfamily Stratiomyinae. ...

Multifaceted re-analysis of the enigmatic Kitimat slide complex, Canada

NASA Astrophysics Data System (ADS)

Stacey, Cooper D.; Lintern, D. Gwyn; Enkin, Randolph J.

2018-07-01

Repeat submarine landslides are challenging to study due to the tendency of subsequent slides to destroy previous deposits. Repeat slides are common in fjord head deltas where high amounts of sediment are focused in narrow valleys. This study examines a well-known slide deposit associated with the Kitimat Delta on Canada's west coast that has been linked to tsunamigenic landslides in 1974 and 1975. For the first time we incorporate multibeam bathymetry to a multifaceted dataset including new high resolution acoustic data and sediment cores to examine the history of submarine slides at the Kitimat Delta. Based on morphological analysis and age modelling using 210Pb and 14C data, we determine that the complex surface morphology of the slide lobe consists of at least two large slide deposits that reach 5 km from the delta: the known event that occurred in 1975 and an older event that occurred at 623 ± 83 cal BP (95% confidence interval). We demonstrate that slide deposits can be differentiated based on surface morphology and acoustic character. This is confirmed by age modelling. The 1975 slide resulted in a flow that ploughed through the seabed creating compression and translation along a basal shear plane, resulting in deep deformation and a surface characterized by pressure ridges. The 623 ± 83 cal BP event resulted in a large amount of blocky slide material that overran the former seafloor and was transported >5 km from the delta front. Several buried events are observed at depth, one of which occurred at 2592 ± 84 cal BP and appears to be on the same order of magnitude as the 1975 event and showing very similar acoustic characteristics. As for hazard implications, we show submarine landslides of varying sizes have naturally occurred on this delta throughout the past several thousand years.

Enigmatic Fossils from the Lower Carboniferous Shrimp Bed, Granton, Scotland.

PubMed

Zapalski, Mikołaj K; Clarkson, Euan N K

2015-01-01

The Lower Carboniferous (Visean) Granton Lagerstätte (Edinburgh, Scotland) is principally known for the discovery of the conodont animal, but has also yielded numerous crustaceans and other faunas. Here we report on small branching colonies, reaching 10 mm in length. They are small, erect, arborescent, and irregularly branched with predominant monopodial and dichotomous growth. They bud in a single plane. In one specimen the wall microstructure is well preserved and it is composed of evenly spaced, linear fibers, running parallel to the axis of the stems, and connected by transverse bars. We discuss possible biological affinities of these organisms; we consider algal, poriferan, hydrozoan and bryozoan affinities. The general pattern of branching, presence of fan-like structures (interpreted here as possible gonophores) and microstructure suggests affinity to Hydrozoa, affinity to non-calcifying algae is less likely. Assuming hydrozoan nature; the microstructure might suggest affinities with the extant family Solanderiidae Marshall, 1892 that possess an internal chitinous skeleton. The EDS analysis shows that fossils discussed here are preserved as phosphates. The skeletons were probably not mineralized, the presence of phosphorus suggests that the colonies were originally composed of chitin. We describe these organisms as Caledonicratis caridum gen. et sp. nov. (Solanderiidae?, Capitata?). Colonies of C. caridum gen et. sp. nov. sometimes encrust the exuviae of crustaceans, which very probably lived in fresh to brackish water thus indicating a likely habitat of Caledonicratis.

Inference of facultative mobility in the enigmatic Ediacaran organism Parvancorina.

PubMed

Darroch, Simon A F; Rahman, Imran A; Gibson, Brandt; Racicot, Rachel A; Laflamme, Marc

2017-05-01

Establishing how Ediacaran organisms moved and fed is critical to deciphering their ecological and evolutionary significance, but has long been confounded by their non-analogue body plans. Here, we use computational fluid dynamics to quantitatively analyse water flow around the Ediacaran taxon Parvancorina , thereby testing between competing models for feeding mode and mobility. The results show that flow was not distributed evenly across the organism, but was directed towards localized areas; this allows us to reject osmotrophy, and instead supports either suspension feeding or detritivory. Moreover, the patterns of recirculating flow differ substantially with orientation to the current, suggesting that if Parvancorina was a suspension feeder, it would have been most efficient if it was able to re-orient itself with respect to current direction, and thus ensure flow was directed towards feeding structures. Our simulations also demonstrate that the amount of drag varied with orientation, indicating that Parvancorina would have greatly benefited from adjusting its position to minimize drag. Inference of facultative mobility in Parvancorina suggests that Ediacaran benthic ecosystems might have possessed a higher proportion of mobile taxa than currently appreciated from trace fossil studies. Furthermore, this inference of movement suggests the presence of musculature or appendages that are not preserved in fossils, but which would noneltheless support a bilaterian affinity for Parvancorina . © 2017 The Author(s).

The patient with chronic epididymitis: characterization of an enigmatic syndrome.

PubMed

Nickel, J Curtis; Siemens, D Robert; Nickel, Kyle R; Downey, Joe

2002-04-01

We provide a baseline description of men diagnosed with chronic epididymitis, explore relevant associations that may be important etiological factors and suggest a classification system and specific symptom assessment tool. Men diagnosed with chronic epididymitis, described as symptoms of discomfort or pain at least 3 months in duration in the scrotum, testicle or epididymis localized to 1 or each epididymis on clinical examination, completed an extensive specific clinical inventory questionnaire. Evaluation included demographics, preceding and concurrent clinical history, duration since diagnosis, associated and previous clinical associations, frequency and severity of prostatitis, voiding and sexual symptoms, specific and general quality of life, and history of investigation and/or treatment for the condition. Volunteers with no past or concurrent history of chronic epididymitis completed similar clinical inventory questionnaires. A total of 50 consecutive men 21 to 83 years old (average age 46) diagnosed with chronic epididymitis who had an average symptom duration of 4.9 years (range 0.25 to 29) were enrolled in the study. The average pain score plus or minus standard deviation was 4.7 +/- 2.1 (range 0 to 10). Of the men 16% were reasonably satisfied with their quality of life. Although 66% of the patients thought about the symptoms some or a lot, in only 30% did symptoms keep them from doing the kinds of things that they would usually do. The most common previous therapies recollected by the patients were antibiotics (74%) and anti-inflammatory agents (36%). At the time of the survey 26% of the men were on some type of pain medication. There were no significant epidemiological, sexual, medical or associated factors that differentiated patients with chronic epididymitis from the 20 controls. A chronic epididymitis classification system (inflammatory, obstructive and epididymalgia) and a symptom assessment index based on assessing pain and quality of life-impact was developed. This comprehensive clinical survey of men diagnosed with chronic epididymitis is the first step for defining and characterizing this particular population. Development of a classification system and symptom assessment index may direct further studies in the etiology, epidemiology and management of chronic epididymitis.

Chiari III malformation: a comprehensive review of this enigmatic anomaly.

PubMed

Ivashchuk, Galyna; Loukas, Marios; Blount, Jeffrey P; Tubbs, R Shane; Oakes, W Jerry

2015-11-01

Chiari III is one of the rarest of the Chiari malformations and is characterized by a high cervical or low occipital encephalocele and osseous defect with or without spinal cord involvement and may include many of the anatomical characteristics seen in the Chiari II malformation. Herein, we provide a comprehensive review of this rare anomaly as well as a translation of Chiari's original description. We review all reported cases of Chiari III malformation found in the extant literature. Out of 57 reported cases of Chiari III malformation, encephaloceles were in a high cervical/low occipital position in 23, 8 were in a high cervical position, 17 were in low occipital position, and the position in 9 cases was not reported. The pathogenesis of Chiari III malformation remains unclear. The majority of patients have concomitant hydrocephalus. Brain parts occurring in the sac from the most to least common include the following: cerebellum, occipital lobe, and parietal lobe. The severity of symptoms is correlated with the amount of brain structures within the encephalocele. Neurologic functional outcomes have been varied and depend on the neurological status of the patient before surgery.

The Mammalian Diving Response: An Enigmatic Reflex to Preserve Life?

PubMed Central

2013-01-01

The mammalian diving response is a remarkable behavior that overrides basic homeostatic reflexes. It is most studied in large aquatic mammals but is seen in all vertebrates. Pelagic mammals have developed several physiological adaptations to conserve intrinsic oxygen stores, but the apnea, bradycardia, and vasoconstriction is shared with those terrestrial and is neurally mediated. The adaptations of aquatic mammals are reviewed here as well as the neural control of cardiorespiratory physiology during diving in rodents. PMID:23997188

Titan: Putting it all Together

NASA Image and Video Library

2011-08-01

Three of Titan major surface features-dunes, craters and the enigmatic Xanadu-appear in this radar image from NASA Cassini spacecraft. The hazy bright area at the left that extends to the lower center of the image marks the northwest edge of Xanadu.

A More Desirable Balanced Polyunsaturated Fatty Acid Composition Achieved by Heterologous Expression of Δ15/Δ4 Desaturases in Mammalian Cells

PubMed Central

Zhu, Guiming; Ou, Qin; Zhang, Tao; Jiang, Xudong; Sun, Guozhi; Zhang, Ning; Wang, Kunfu; Fang, Heng; Wang, Mingfu; Sun, Jie; Ge, Tangdong

2013-01-01

Arachidonic (ARA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are the most biologically active polyunsaturated fatty acids, but their biosyntheses in mammals are very limited. The biosynthesis of DHA is the most difficult, because this undergoes the Sprecher pathway–a further elongation step from docosapentaenoic acid (DPA), a Δ6-desaturase acting on a C24 fatty acid substrate followed by a peroxisomal chain shortening step. This paper reports the successful heterologous expression of two non-mammalian genes (with modification of codon usage), coding for Euglena gracilis Δ4-desaturase and Siganus canaliculatus Δ4-desaturase respectively, in mammalian cells (HEK293 cell line). Both of the Δ4-desaturases can efficiently function, directly converting DPA into DHA. Moreover, the cooperation of the E. gracilis Δ4-desaturase with C. elegans Δ15-desaturase (able to convert a number of n-6 PUFAs to their corresponding n-3 PUFAs) in transgenic HEK293 cells made a more desirable fatty acid composition – a drastically reduced n-6/n-3 PUFAs ratio and a high level of DHA as well as EPA and ARA. Our findings provide a basis for potential applications of the gene constructs for expression of Δ15/Δ4-desaturases in transgenic livestock to produce such a fatty acid profile in the related products, which certainly will bring benefit to human health. PMID:24391980

Locomotion in ornithischian dinosaurs: an assessment using three-dimensional computational modelling.

PubMed

Maidment, Susannah C R; Bates, Karl T; Falkingham, Peter L; VanBuren, Collin; Arbour, Victoria; Barrett, Paul M

2014-08-01

Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the

Numerical Estimation of Balanced and Falling States for Constrained Legged Systems

NASA Astrophysics Data System (ADS)

Mummolo, Carlotta; Mangialardi, Luigi; Kim, Joo H.

2017-08-01

Instability and risk of fall during standing and walking are common challenges for biped robots. While existing criteria from state-space dynamical systems approach or ground reference points are useful in some applications, complete system models and constraints have not been taken into account for prediction and indication of fall for general legged robots. In this study, a general numerical framework that estimates the balanced and falling states of legged systems is introduced. The overall approach is based on the integration of joint-space and Cartesian-space dynamics of a legged system model. The full-body constrained joint-space dynamics includes the contact forces and moments term due to current foot (or feet) support and another term due to altered contact configuration. According to the refined notions of balanced, falling, and fallen, the system parameters, physical constraints, and initial/final/boundary conditions for balancing are incorporated into constrained nonlinear optimization problems to solve for the velocity extrema (representing the maximum perturbation allowed to maintain balance without changing contacts) in the Cartesian space at each center-of-mass (COM) position within its workspace. The iterative algorithm constructs the stability boundary as a COM state-space partition between balanced and falling states. Inclusion in the resulting six-dimensional manifold is a necessary condition for a state of the given system to be balanced under the given contact configuration, while exclusion is a sufficient condition for falling. The framework is used to analyze the balance stability of example systems with various degrees of complexities. The manifold for a 1-degree-of-freedom (DOF) legged system is consistent with the experimental and simulation results in the existing studies for specific controller designs. The results for a 2-DOF system demonstrate the dependency of the COM state-space partition upon joint-space configuration (elbow-up vs

The multi-modal responses of a physical head model subjected to various blast exposure conditions

NASA Astrophysics Data System (ADS)

Ouellet, S.; Philippens, M.

2018-01-01

The local and global biomechanical response of the body to a blast wave is the first step of a sequence that leads to the development of stresses and strains which can exceed the tolerance of brain tissue. These stresses and strains may then lead to neuro-physical changes in the brain and contribute to initiate a cascade of events leading to injury. The specific biomechanical pathways by which the blast energy is transmitted through the head structure are, however, not clearly understood. Multiple transmission mechanisms have been proposed to explain the generation of brain stresses following the impingement of a blast wave on the head. With the use of a physical head model, the work presented here aims at demonstrating that the proposed transmission mechanisms are not mutually exclusive. They are part of a continuum of head responses where, depending on the exposure conditions, a given mechanism may or may not dominate. This article presents the joint analysis of previous blast test results generated with the brain injury protection evaluation device (BIPED) headform under four significantly different exposure conditions. The focus of the analysis is to demonstrate how the nature of the recorded response is highly dependent on the exposure characteristics and consequently, on the method used to reproduce blast exposure in a laboratory environment. The timing and magnitude of the variations in intra-cranial pressures (ICP) were analysed relative to the external pressure field in order to better understand the wave dynamics occurring within the brain structure of the headform. ICP waveforms were also analysed in terms of their energy spectral density to better identify the energy partitioning between the different modes of response. It is shown that the BIPED response is multi-modal and that the energy partitioning between its different modes of response is greatly influenced by exposure characteristics such as external peak overpressure, impulse, blast wave

A novel in vivo model for assessing the impact of geophagic earth on iron status

USDA-ARS?s Scientific Manuscript database

The causes and consequences of geophagy, the craving and consumption of earth, remain enigmatic, despite its recognition as a behavior with public health implications. Iron deficiency has been proposed as both a cause and consequence of geophagy, but methodological limitations have precluded a decis...

Explicit Differences.

ERIC Educational Resources Information Center

Standish, Paul

1995-01-01

Identifies authenticity as the idea that there exists an innate and knowable self. Discusses this concept and how it relates to social, philosophical, and religious thought. Compares the Western concept of self, autonomous and individualistic, with the more interdependent and enigmatic Eastern ideal. (MJP)

SOA VOLATILITY EVOLUTION: FORMATION AND OXIDATION OVER THE LIFECYCLE OF PM2.5

EPA Science Inventory

Secondary Organic Aerosols are a major, possibly dominant, source of organic PM_2.5 that remain enigmatic. Enormous progress has been made in the past 15 years regarding SOA formation, starting with recognition that most SOA products are semivolatile, continuing to a...

Material Voices: Intermediality and Autism

ERIC Educational Resources Information Center

Trimingham, Melissa; Shaughnessy, Nicola

2016-01-01

Autism continues to be regarded enigmatically; a community that is difficult to access due to perceived disruptions of interpersonal connectedness. Through detailed observations of two children participating in the Arts and Humanities Research Council funded project "Imagining Autism: Drama, Performance and Intermediality as Interventions for…

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2016-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Walking dynamics of the passive compass-gait model under OGY-based control: Emergence of bifurcations and chaos

NASA Astrophysics Data System (ADS)

Gritli, Hassène; Belghith, Safya

2017-06-01

An analysis of the passive dynamic walking of a compass-gait biped model under the OGY-based control approach using the impulsive hybrid nonlinear dynamics is presented in this paper. We describe our strategy for the development of a simplified analytical expression of a controlled hybrid Poincaré map and then for the design of a state-feedback control. Our control methodology is based mainly on the linearization of the impulsive hybrid nonlinear dynamics around a desired nominal one-periodic hybrid limit cycle. Our analysis of the controlled walking dynamics is achieved by means of bifurcation diagrams. Some interesting nonlinear phenomena are displayed, such as the period-doubling bifurcation, the cyclic-fold bifurcation, the period remerging, the period bubbling and chaos. A comparison between the raised phenomena in the impulsive hybrid nonlinear dynamics and the hybrid Poincaré map under control was also presented.

Trotting, pacing and bounding by a quadruped robot.

PubMed

Raibert, M H

1990-01-01

This paper explores the quadruped running gaits that use the legs in pairs: the trot (diagonal pairs), the pace (lateral pairs), and the bound (front and rear pairs). Rather than study these gaits in quadruped animals, we studied them in a quadruped robot. We found that each of the gaits that use the legs in pairs can be transformed into a common underlying gait, a virtual biped gait. Once transformed, a single set of control algorithms produce all three gaits, with modest parameter variations between them. The control algorithms manipulated rebound height, running speed, and body attitude, while a low-level mechanism coordinated the behavior of the legs in each pair. The approach was tested with laboratory experiments on a four-legged robot. Data are presented that show the details of the running motion for the three gaits and for transitions from one gait to another.

Zoology: Invertebrates that Parasitize Invertebrates.

PubMed

Giribet, Gonzalo

2016-07-11

The genome of an orthonectid, a group of highly modified parasitic invertebrates, is drastically reduced and compact, yet it shows the bilaterian gene toolkit. Phylogenetic analyses place the enigmatic orthonectids within Spiralia, although their exact placement remains uncertain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adopting the Transformational Leadership Perspective in a Complex Research Environment

ERIC Educational Resources Information Center

Atkinson, Timothy N.; Pilgreen, Tom

2011-01-01

Transformational Leadership is a popular topic among leadership scholars, but for research administrators, Transformational Leadership might seem like an enigmatic approach given its various contexts. Research administrators might think the transformational approach is only for executives, or that they do not have enough staff to call themselves…

A Historical Perspective on the Dichotomy of Arsenic as a Poison and Medicinal Agent

EPA Science Inventory

Arsenic is one of the most interesting and enigmatic elements of the periodic table. Its use as an intentional poison has been known for centuries and occasionally occurs today. Arsenic has been called the “King of Poisons”, because it had been used to poison royalt...

Gut microbiomes of Malawian twin pairs discordant for kwashiorkor

USDA-ARS?s Scientific Manuscript database

Kwashiorkor, an enigmatic form of severe acute malnutrition, is the consequence of inadequate nutrient intake plus additional environmental insults. To investigate the role of the gut microbiome, we studied 317 Malawian twin pairs during the first 3 years of life. During this time, half of the twin ...

Frankixalus, a New Rhacophorid Genus of Tree Hole Breeding Frogs with Oophagous Tadpoles

PubMed Central

Biju, S. D.; Mahony, Stephen; Kamei, Rachunliu G.; Thomas, Ashish; Shouche, Yogesh; Raxworthy, Christopher J.; Meegaskumbura, Madhava; Bocxlaer, Ines Van

2016-01-01

Despite renewed interest in the biogeography and evolutionary history of Old World tree frogs (Rhacophoridae), this family still includes enigmatic frogs with ambiguous phylogenetic placement. During fieldwork in four northeastern states of India, we discovered several populations of tree hole breeding frogs with oophagous tadpoles. We used molecular data, consisting of two nuclear and three mitochondrial gene fragments for all known rhacophorid genera, to investigate the phylogenetic position of these new frogs. Our analyses identify a previously overlooked, yet distinct evolutionary lineage of frogs that warrants recognition as a new genus and is here described as Frankixalus gen. nov. This genus, which contains the enigmatic ‘Polypedates’ jerdonii described by Günther in 1876, forms the sister group of a clade containing Kurixalus, Pseudophilautus, Raorchestes, Mercurana and Beddomixalus. The distinctiveness of this evolutionary lineage is also corroborated by the external morphology of adults and tadpoles, adult osteology, breeding ecology, and life history features. PMID:26790105

Understanding "Lord of the Flies": A Student Casebook to Issues, Sources, and Historical Documents.

ERIC Educational Resources Information Center

Olsen, Kirstin

A seemingly simple tale of schoolboys marooned on an island, the novel "Lord of the Flies" is an enigmatic and provocative piece of literature. This casebook probes the many layers of meaning in the novel, examining its literary, philosophical, historical, scientific, and religious significance. The casebook integrates analysis and…

From Yoknapatawpha to Piratininga and Beyond: Antônio Dutra's "Dias De Faulkner"

ERIC Educational Resources Information Center

Valente, Luiz Fernando

2015-01-01

By reimagining William Faulkner's 1954 visit to Brazil, Antônio Dutra's "Dias de Faulkner" (2008) establishes a creative dialogue with Faulkner's "oeuvre" while also inquiring into the author's enigmatic personality. In the process Dutra's narrative invites us to reflect on the complex and contradictory relationship between the…

The first ITS phylogeny of the genus Cantharocybe (Agaricales, Hygrophoraceae) with a new record of C. virosa from Bangladesh

Treesearch

Md. Iqbal Hosen; Tai-Hui Li; D. Jean Lodge; Alan Rockefeller

2016-01-01

This is the first internal transcribed spacer (ITS) phylogeny of the enigmatic genus Cantharocybe and includes ITS sequences from two out of the three holotype collections. Two species are reported from the Americas and only a single species from Asia. Additionally, a collection of Cantharocybe virosa collected from tropical...

ADHD Perspectives: Medicalization and ADHD Connectivity

ERIC Educational Resources Information Center

Wright, Gloria Sunnie

2012-01-01

Today's "ADHDscape" is no longer confined to images of fidgety children falling off classroom chairs. Trans-generational images flood popular culture, from "ADHD creator" with entrepreneurial style, to "ADHD troublemaker". Indeed, ADHD's enigmatic characteristics seem to apply as much to crying babies as to forgetful grannies. With the recent…

New higher taxa in the lichen family Graphidaceae (lichenized Ascomycota: Ostropales) based on a three-gene skeleton phylogeny

Treesearch

H. Thorsten Lumbsch; Ekaphan Kraichak; Sittiporn Parnmen; Eimy Rivas Plata; Andre Aptroot; Marcela E.S. Caceres; Damien Ertz; Shirley Cunha Feuerstein; Joel A. Mercado-Diaz; Bettina Staiger; Dries Van den Broeck; Robert Lücking

2014-01-01

We provide an updated skeleton phylogeny of the lichenized family Graphidaceae (excluding subfamily Gomphilloideae), based on three loci (mtSSU, nuLSU, RPB2), to elucidate the position of four new genera, Aggregatorygma, Borinquenotrema, Corticorygma, and Paratopeliopsis, as well as the placement of the enigmatic species Diorygma erythrellum, Fissurina monilifera, and...

Microbial diversity: a bonanza of phyla.

PubMed

Eme, Laura; Doolittle, W Ford

2015-03-16

Metagenomics and single-cell genomics are now the gold standard for exploring microbial diversity. A new study focusing on enigmatic ultra-small archaea greatly expands known genetic diversity within Archaea, and reports the first complete archaeal genomes reconstructed from metagenomic data only. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pelvic and hindlimb musculature of Tyrannosaurus rex (Dinosauria: Theropoda).

PubMed

Carrano, Matthew T; Hutchinson, John R

2002-09-01

In this article, we develop a new reconstruction of the pelvic and hindlimb muscles of the large theropod dinosaur Tyrannosaurus rex. Our new reconstruction relies primarily on direct examination of both extant and fossil turtles, lepidosaurs, and archosaurs. These observations are placed into a phylogenetic context and data from extant taxa are used to constrain inferences concerning the soft-tissue structures in T. rex. Using this extant phylogenetic bracket, we are able to offer well-supported inferences concerning most of the hindlimb musculature in this taxon. We also refrain from making any inferences for certain muscles where the resulting optimizations are ambiguous. This reconstruction differs from several previous attempts and we evaluate these discrepancies. In addition to providing a new and more detailed understanding of the hindlimb morphology of T. rex--the largest known terrestrial biped--this reconstruction also helps to clarify the sequence of character-state change along the line to extant birds. Copyright 2002 Wiley-Liss, Inc.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking*

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:27990059

Myth or relict: Does ancient DNA detect the enigmatic Upland seal?

PubMed

Salis, Alexander T; Easton, Luke J; Robertson, Bruce C; Gemmell, Neil; Smith, Ian W G; Weisler, Marshall I; Waters, Jonathan M; Rawlence, Nicolas J

2016-04-01

The biological status of the so-called 'Upland seal' has remained contentious ever since historical records described a distinct seal from the uplands of New Zealand's (NZ) remote sub-Antarctic islands. Subsequent genetic surveys of the NZ fur seal (Arctocephalus forsteri) detected two highly-divergent mtDNA clades, hypothesized to represent a post-sealing hybrid swarm between 'mainland' (Australia-NZ; A. forsteri) and sub-Antarctic (putative 'Upland'; A. snaresensis) lineages. We present ancient-DNA analyses of prehistoric mainland NZ and sub-Antarctic fur seals, revealing that both of these genetic lineages were already widely distributed across the region at the time of human arrival. These findings indicate that anthropogenic factors did not contribute to the admixture of these lineages, and cast doubt on the validity of the Upland seal. Human-mediated impacts on Arctocephalus genetic diversity are instead highlighted by a dramatic temporal haplotype frequency-shift due to genetic drift in heavily bottlenecked populations following the cessation of industrial-scale harvesting. These extinction-recolonisation dynamics add to a growing picture of human-mediated change in NZ's coastal and marine ecosystems. Copyright © 2015 Elsevier Inc. All rights reserved.

The Enigmatic (Almost) Dark Galaxy Coma P: The Atomic Interstellar Medium

NASA Astrophysics Data System (ADS)

Ball, Catherine; Cannon, John M.; Leisman, Lukas; Adams, Elizabeth A. K.; Haynes, Martha P.; Józsa, Gyula I. G.; McQuinn, Kristen B. W.; Salzer, John J.; Brunker, Samantha; Giovanelli, Riccardo; Hallenbeck, Gregory; Janesh, William; Janowiecki, Steven; Jones, Michael G.; Rhode, Katherine L.

2018-02-01

We present new high-resolution H I spectral line imaging of Coma P, the brightest H I source in the system HI 1232+20. This galaxy with extremely low surface brightness was first identified in the ALFALFA survey as an “(Almost) Dark” object: a clearly extragalactic H I source with no obvious optical counterpart in existing optical survey data (although faint ultraviolet emission was detected in archival GALEX imaging). Using a combination of data from the Westerbork Synthesis Radio Telescope and the Karl G. Jansky Very Large Array, we investigate the H I morphology and kinematics at a variety of physical scales. The H I morphology is irregular, reaching only moderate maxima in mass surface density (peak {σ }{{H}{{I}}}∼ 10 {M}ȯ pc‑2). Gas of lower surface brightness extends to large radial distances, with the H I diameter measured at 4.0 ± 0.2 kpc inside the 1 {M}ȯ pc‑2 level. We quantify the relationships between mass surface density of H I gas and star formation on timescales of ∼100–200 Myr as traced by GALEX far-ultraviolet emission. While Coma P has regions of dense H I gas reaching the {N}{{H}{{I}}}={10}21 cm‑2 level typically associated with ongoing star formation, it lacks massive star formation as traced by Hα emission. The H I kinematics are extremely complex: a simple model of a rotating disk cannot describe the H I gas in Coma P. Using spatially resolved position–velocity analysis we identify two nearly perpendicular axes of projected rotation that we interpret as either the collision of two H I disks or a significant infall event. Similarly, three-dimensional modeling of the H I dynamics provides a best fit with two H I components. Coma P is just consistent (within 3σ) with the known {M}{{H}{{I}}}{--}{D}{{H}{{I}}} scaling relation. It is either too large for its H I mass, has too low an H I mass for its H I size, or the two H I components artificially extend its H I size. Coma P lies within the empirical scatter at the faint end of the baryonic Tully–Fisher relation, although the complexity of the H I dynamics complicates the interpretation. Along with its large ratio of H I to stellar mass, the collective H I characteristics of Coma P make it unusual among known galaxies in the nearby universe.

The enigmatic ultra-long run-out of seafloor density driven flows

NASA Astrophysics Data System (ADS)

Dorrell, R. M.

2017-12-01

Dilute, particulate-laden, density-driven flows - turbidity currents - are a predominant mechanism for transporting sediment from source to sink in deep marine environments. These flows sculpt channels on the seafloor and, as evidenced by a wealth of bathymetric data, can travel for >1000km, forming some of the largest sedimentary landforms on the planet. For turbidity currents to travel such large dsitances, sediment must be self-maintained in suspension, i.e., be in a state of autosuspension. It has been shown that such self-maintained sediment suspensions can only occur whilst inertial forces are greater than gravitational forces, entailing supercritical flow. This conclusion is paradoxical, as inertia dominated flows rapidly entrain fluid, thereby thickening and slowing to become subcritical. However, current theory can only truly be applied to the proximal upper slope regions of seafloor channels where incised flows are fully confined. This contrasts with the distal reaches of long run out turbidity current systems, where the flow is only partially confined through self-channelization. Here it is shown that overspill of partially confined flow has a significant effect on the hydro- and morphodynamics of turbidity current systems. A new model is derived that shows that channel overspill acts to negate the effects of ambient fluid entrainment: a dynamic balance that limits increases in flow depth and maintains supercritical flow throughout the channel. In the new model mass, momentum and energy conservation is modulated by flow overspill onto channel banks, necessarily requiring description of the vertical structure of the flow. Analysis of continuously stratified steady state flow dynamics shows that the integration of overspill and stratification is necessary to enable maintained autosuspension and thus predict the ultra-long run-out of turbidity currents.

An enigmatic aquatic snake from the Cenomanian of Northern South America

PubMed Central

Carrillo-Briceño, Jorge D.; Neenan, James M.

2016-01-01

We report the first record of a snake from the Cretaceous of northern South America. The remains come from the La Luna Formation (La Aguada Member, Cenomanian of Venezuela) and consist of several vertebrae, which belong to the precloacal region of the vertebral column. Comparisons to extant and extinct snakes show that the remains represent a new taxon, Lunaophis aquaticus gen. et sp nov. An aquatic mode of life is supported by the ventral position of the ribs, indicating a laterally compressed body. The systematic relationships of this new taxon are difficult to determine due to the scarcity of fossil material; it is, however, a representative of an early lineage of snakes that exploited tropical marine pelagic environments, as reflected by the depositional conditions of the La Aguada Member. Lunaophis is also the first aquatic snake from the Cenomanian found outside of the African and European Tethyan and Boreal Zones. PMID:27257536

'Actual neurosis' and psychosomatic medicine: the vicissitudes of an enigmatic concept.

PubMed

Hartocollis, Peter

2002-12-01

Out of the concept of neurasthenia, the main non-psychotic diagnosis of nineteenth-century psychiatry besides hysteria, and on the basis of psychophysiological problems of his own, self-diagnosed as neurasthenia, Freud developed the notion of 'actual neurosis', a 'contentless psychic state' manifested by various somatic symptoms and a depressive mood, which he attributed to a chemical factor associated with aberrant sexual practices and in particular masturbation. Rejected by post-Freudian analysts as such along with the diagnosis of neurasthenia, the concept of 'actual neurosis' has survived under various theoretical schemes that seek to explain psychosomatic illness and somatisation, in general, with its concomitant poverty of affects and dearth of fantasy life. In more recent years, the concept of 'actual neurosis' has resurfaced under the label of chronic fatigue syndrome, a medical entity thought to be an immunological deficiency, while in psychoanalysis Freud's idea of a contentless mental state has been replaced by that of unconscious fantasy and symbolisation at a pre-genital or pre-verbal level.

The identity of the enigmatic "Black Shrew" (Sorex niger Ord, 1815)

USGS Publications Warehouse

Woodman, Neal

2013-01-01

The scientific name Sorex niger Ord, 1815 (Mammalia, Soricidae) was originally applied to a North American species that George Ord called the “Black Shrew.” The origin of the name “Black Shrew,” however, was obscure, and Samuel Rhoads subsequently wrote that the species represented by this name could not be determined. The names Sorex niger Ord and Black Shrew have since been mostly forgotten. Two of Ord's contemporaries, however, noted that Ord's use of these names probably alluded to Benjamin Smith Barton's Black Shrew, whose discovery near Philadelphia was announced by Barton in 1806. Examination of two unpublished illustrations of the Black Shrew made by Barton indicates that the animal depicted is Blarina brevicauda (Say, 1822). Had the connection between Ord's and Barton's names been made more clearly, one of the most common mammals in eastern North America would bear a different scientific name today. This connection also would have affected the validity of Sorex niger Horsfield, 1851. While Sorex niger Ord remains a nomen nudum, the animal it referenced can now be identified.

An enigmatic new stick insect from the Philippine Islands (Insecta: Phasmatodea).

PubMed

Gottardo, Marco; Heller, Philipp

2012-09-01

A new genus and species of stick insect is described and figured from Mount Halcon, on the Philippine island of Mindoro. Conlephasma enigma gen. et sp. n. is a stout, flightless, and apparently ground-dwelling species with vivid integumental colors. When disturbed, specimens spray a defensive secretion from the prothoracic exocrine glands. The systematic position of Conlephasma within Euphasmatodea is unclear. The elongated galealobulus and the trichome area located laterally in the galea, represent unusual apomorphic characters of the maxilla that could indicate affinities with Necrosciinae or Pseudophasmatinae. All tibiae exhibit the anareolate condition. Euplantulae are of two types: those of tarsomeres I-IV feature a nubby microstructure, whilst the one on the ventral side of the pretarsus is smooth. Males are characterized by the presence of a well-developed vomer on the tenth abdominal segment. A distinctive and apomorphic trait of female terminalia is represented by the elongated tenth abdominal tergum. Conlephasma can represent an interesting taxon for studies on the evolution of the stick and leaf insects. Copyright © 2012 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

The enigmatic molar from Gondolin, South Africa: implications for Paranthropus paleobiology.

PubMed

Grine, Frederick E; Jacobs, Rachel L; Reed, Kaye E; Plavcan, J Michael

2012-10-01

The specific attribution of the large hominin M(2) (GDA-2) from Gondolin has significant implications for the paleobiology of Paranthropus. If it is a specimen of Paranthropus robustus it impacts that species' size range, and if it belongs to Paranthropus boisei it has important biogeographic implications. We evaluate crown size, cusp proportions and the likelihood of encountering a large-bodied mammal species in both East and South Africa in the Early Pleistocene. The tooth falls well outside the P. robustus sample range, and comfortably within that for penecontemporaneous P. boisei. Analyses of sample range, distribution and variability suggest that it is possible, albeit unlikely to find a M(2) of this size in the current P. robustus sample. However, taphonomic agents - carnivore (particularly leopard) feeding behaviors - have likely skewed the size distribution of the Swartkrans and Drimolen P. robustus assemblage. In particular, assemblages of large-bodied mammals accumulated by leopards typically display high proportions of juveniles and smaller adults. The skew in the P. robustus sample is consistent with this type of assemblage. Morphological evidence in the form of cusp proportions is congruent with GDA-2 representing P. robustus rather than P. boisei. The comparatively small number of large-bodied mammal species common to both South and East Africa in the Early Pleistocene suggests a low probability of encountering an herbivorous australopith in both. Our results are most consistent with the interpretation of the Gondolin molar as a very large specimen of P. robustus. This, in turn, suggests that large, presumptive male, specimens are rare, and that the levels of size variation (sexual dimorphism) previously ascribed to this species are likely to be gross underestimates. Copyright © 2012 Elsevier Ltd. All rights reserved.

Isoprene research - 60 years later, the biology is still enigmatic.

PubMed

Sharkey, Thomas D; Monson, Russell K

2017-09-01

Isoprene emission is a major component of biosphere-atmosphere interactions. It is the single largest source of non-methane hydrocarbon in the atmosphere. The first report of isoprene emission from plants was published in 1957 by Professor Guivi Sanadze. While humans have smelled the monoterpene hydrocarbons made by coniferous trees since their earliest migrations, only in 1957 did the world became aware that other trees make a type of hydrocarbon in even greater amounts but one to which the human nose is much less sensitive. For this 60th anniversary of the first report of isoprene emission from leaves, we trace the discovery and development of the research field, highlighting some of the most seminal observations and theoretical interpretations. This is not an exhaustive review, and many important papers are not cited, but we hope it will be of general interest to read how research in this field developed, how new observations forced us to reevaluate our theories about the significance of isoprene biosynthesis to plant physiology and adaptation and how scientific serendipity can sometimes drive a topic forward. © 2017 John Wiley & Sons Ltd.

Postmating sexual selection and the enigmatic jawed genitalia of Callosobruchus subinnotatus

PubMed Central

Rönn, Johanna Liljestrand; Schilthuizen, Menno; Arnqvist, Göran

2017-01-01

ABSTRACT Insect genitalia exhibit rapid divergent evolution. Truly extraordinary structures have evolved in some groups, presumably as a result of postmating sexual selection. To increase our understanding of this phenomenon, we studied the function of one such structure. The male genitalia of Callosobruchus subinnotatus (Coleoptera: Bruchinae) contain a pair of jaw-like structures with unknown function. Here, we used phenotypic engineering to ablate the teeth on these jaws. We then experimentally assessed the effects of ablation of the genital jaws on mating duration, ejaculate weight, male fertilization success and female fecundity, using a double-mating experimental design. We predicted that copulatory wounding in females should be positively related to male fertilization success; however, we found no significant correlation between genital tract scarring in females and male fertilization success. Male fertilization success was, however, positively related to the amount of ejaculate transferred by males and negatively related to female ejaculate dumping. Ablation of male genital jaws did not affect male relative fertilization success but resulted in a reduction in female egg production. Our results suggest that postmating sexual selection in males indeed favors these genital jaws, not primarily through an elevated relative success in sperm competition but by increasing female egg production. PMID:28583926

AN ENIGMATIC POINT-LIKE FEATURE WITHIN THE HD 169142 TRANSITIONAL DISK ,

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biller, Beth A.; Males, Jared; Morzinski, Katie

2014-09-01

We report the detection of a faint point-like feature possibly related to ongoing planet-formation in the disk of the transition disk star HD 169142. The point-like feature has a Δmag(L) ∼ 6.4, at a separation of ∼0.''11 and position angle ∼0°. Given its lack of an H or K{sub S} counterpart despite its relative brightness, this candidate cannot be explained by purely photospheric emission and must be a disk feature heated by an as yet unknown source. Its extremely red colors make it highly unlikely to be a background object, but future multi-wavelength follow up is necessary for confirmation and characterization ofmore » this feature.« less

The enigmatic genus Stenichnoteras scott from the seychelles (Coleoptera: Staphylinidae: Scydmaeninae).

PubMed

Jałoszyński, Paweł

2014-06-03

The genus Stenichnoteras, known from the Seychelles and represented by a single known species, St. montanum, is redescribed and redefined. The morphological structures of St. montanum are described and illustrated in detail. Similarities and possible affinities with other genera of Cyrtoscydmini are discussed, and it is concluded that Stenichnoteras may be closely related to Euconnus, despite an apparent difference in the shape of prothorax and some mesoventral structures.

The biology of gall-inducing arthropods.

Treesearch

Gyuri Csoka; William J. Mattson; Graham N. Stone; Peter W. Price

1998-01-01

This proceedings explores many facets of the ever intriguing and enigmatic relationships between plants and their gall-forming herbivores. The research reported herein ranges from studies on classical biology and systematics of galling to molecular phylogeny, population genetics, and ecological and evolutionary theory. Human kind has much to learn and gain from...

Student Life on the Autism Spectrum: Helping to Build a More Inclusive Campus

ERIC Educational Resources Information Center

Williams, Lee Burdette

2016-01-01

A diagnosis of Autism Spectrum Disorder is, in many ways, both the terminus and the beginning of a journey for families and educators. It is such an individual and enigmatic diagnosis that appropriate accommodations are exceedingly difficult to standardize. It is, however, a campus population that is growing each year (Pinder-Amaker, 2014, p.…

Phloem transport in trees

Treesearch

Michael G. Ryan; Shinichi Asao

2014-01-01

Phloem is like an enigmatic central banker: we know how important phloem is to plant function, but very little about how phloem functions as part of a whole-plant economy. Phloem transports carbohydrates, produced by photosynthesis and hydrolysis of reserve compounds, to sink tissues for growth, respiration and storage. At photosynthetic tissues, carbohydrates are...

Defining the Content of the Undergraduate Systems Analysis and Design Course as Measured by a Survey of Instructors

ERIC Educational Resources Information Center

Burns, Timothy J.

2011-01-01

There are many factors that make the undergraduate systems analysis and design course somewhat enigmatic in its purpose, and therefore equivocal in its delivery. The purpose of this research is to learn, specifically, what instructors are teaching in their systems analysis and design courses. This paper reports the results of a survey and follow…

The oligolectic bee Osmia brevis sonicates Penstemon flowers for pollen: A newly documented behavior for the Megachilidae

Treesearch

James H. Cane

2014-01-01

Flowers with poricidally dehiscent anthers are typically nectarless but are avidly visited and often solely pollinated by bees that sonicate the flowers to harvest pollen. Sonication results from shivering the thoracic flight muscles. Honey bees (Apis) and the 4,000+ species of Megachilidae are enigmatic in their seeming inability to sonicate flowers. The oligolectic...

Paulo Freire's Last Laugh: Rethinking Critical Pedagogy's Funny Bone through Jacques Ranciere

ERIC Educational Resources Information Center

Lewis, Tyson Edward

2010-01-01

In several enigmatic passages, Paulo Freire describes the pedagogy of the oppressed as a "pedagogy of laughter". The inclusion of laughter alongside problem-posing dialogue might strike some as ambiguous, considering that the global exploitation of the poor is no laughing matter. And yet, laughter seems to be an important aspect of the pedagogy of…

Hughes et al.: Science or Promotion?

ERIC Educational Resources Information Center

Loman, L. Anthony; Siegel, Gary L.

2013-01-01

The Hughes et al. paper is critiqued generally and in specific areas. The weak nature of the authors' empirical work is discussed along with their enigmatic writing and vague and incorrect use of references, and their simultaneous use of sweeping statements of opinion and narrow analytical focus. This review examines the authors' errors…

Social and Economic Change in Southern Africa. Fulbright-Hays Summer Seminars Abroad Program, Summer 1991. [Curriculum Projects and Papers.

ERIC Educational Resources Information Center

Institute of International Education, New York, NY.

This document presents curriculum projects and papers written by U.S. teachers who traveled to countries in Southern Africa in the summer of 1991 as part of the Fulbright-Hays Summer Seminars Abroad Program. The included projects and papers are: "Through a Glass Darkly: The Enigmatic Educational System of Botswana" (Alan C. Howard);…

The bellerophont controversy revisited

USGS Publications Warehouse

Harper, J.A.; Rollins, H.B.

2000-01-01

An old controversy reestablished itself in the late 1970s and early 1980s that focused on the systematic placement of the enigmatic Bellerophontoidea (informally, "bellerophonts"), a group of planispirally coiled, wholly fossil molluscs. The controversy embraced three fundamental concepts that are based on different philosophical interpretations of shell form, muscle scar patterns, and other preserved shell features: 1) all bellerophonts were monoplacophorans; 2) all bellerophonts were gastropods; and 3) some bellerophonts were monoplacophorans and some were gastropods. A review of the main issues appearing in the literature since the early 1980s indicates that these three philosophical divisions still exist and, indeed, have become entrenched. An examination of the relevant anatomical and shell features of recent gastropods and monoplacophorans, and comparison with preserved features in enigmatic fossil forms, convinces us that the bellerophontoideans and the coiled and high-domed "monoplacophorans" (Cyclomya) were gastropods. Only the flattened, spoon-and cap-shaped monoplacophorans (Tergomya) were true monoplacophorans. We present a hypothetical scheme for the morphological diversification of gastropods from early monoplacophorans that could account for Cyclomya, Bellerophontoidea, Patellogastropoda, and Prosobranchia.

An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics

PubMed Central

Fu, Chunjiang; Suzuki, Yasuyuki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

2014-01-01

Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather

An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics.

PubMed

Fu, Chunjiang; Suzuki, Yasuyuki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

2014-12-06

Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather

Locomotion training of legged robots using hybrid machine learning techniques

NASA Technical Reports Server (NTRS)

Simon, William E.; Doerschuk, Peggy I.; Zhang, Wen-Ran; Li, Andrew L.

1995-01-01

In this study artificial neural networks and fuzzy logic are used to control the jumping behavior of a three-link uniped robot. The biped locomotion control problem is an increment of the uniped locomotion control. Study of legged locomotion dynamics indicates that a hierarchical controller is required to control the behavior of a legged robot. A structured control strategy is suggested which includes navigator, motion planner, biped coordinator and uniped controllers. A three-link uniped robot simulation is developed to be used as the plant. Neurocontrollers were trained both online and offline. In the case of on-line training, a reinforcement learning technique was used to train the neurocontroller to make the robot jump to a specified height. After several hundred iterations of training, the plant output achieved an accuracy of 7.4%. However, when jump distance and body angular momentum were also included in the control objectives, training time became impractically long. In the case of off-line training, a three-layered backpropagation (BP) network was first used with three inputs, three outputs and 15 to 40 hidden nodes. Pre-generated data were presented to the network with a learning rate as low as 0.003 in order to reach convergence. The low learning rate required for convergence resulted in a very slow training process which took weeks to learn 460 examples. After training, performance of the neurocontroller was rather poor. Consequently, the BP network was replaced by a Cerebeller Model Articulation Controller (CMAC) network. Subsequent experiments described in this document show that the CMAC network is more suitable to the solution of uniped locomotion control problems in terms of both learning efficiency and performance. A new approach is introduced in this report, viz., a self-organizing multiagent cerebeller model for fuzzy-neural control of uniped locomotion is suggested to improve training efficiency. This is currently being evaluated for a possible

A New Age for Algebra

ERIC Educational Resources Information Center

Oishi, Lindsay

2011-01-01

"Solve for x." While many people first encountered this enigmatic instruction in high school, the last 20 years have seen a strong push to get students to take algebra in eighth grade or even before. Today, concerns about the economy highlight a familiar worry: American eighth-graders trailed their peers in five Asian countries on the…

Reading Instruction with Gifted and Talented Readers: A Series of Unfortunate Events or a Sequence of Auspicious Results?

ERIC Educational Resources Information Center

Wood, Patricia F.

2008-01-01

The enigmatic author Lemony Snicket is quick to establish from the start that happy events are not to be expected in his collection, "A Series of Unfortunate Events." Every happy event in the lives of the three clever and charming Baudelaire children is countered with an even more unfortunate one, events rife with misery, misfortune, and despair.…

Forest soil mineral weathering rates: use of multiple approaches

Treesearch

Randy K. Kolka; D.F. Grigal; E.A. Nater

1996-01-01

Knowledge of rates of release of base cations from mineral dissolution (weathering) is essential to understand ecosystem elemental cycling. Although much studied, rates remain enigmatic. We compared the results of four methods to determine cation (Ca + Mg + K) release rates at five forested soils/sites in the northcentral U.S.A. Our premise was that multiple...

The Elephant in the Classroom

ERIC Educational Resources Information Center

Brezicki, Colin G.

2012-01-01

For high school teachers these are enigmatic times. Teachers want to prepare students for life in the real world, but balk at teaching them the truth of that world. The recent publication of a corrected "Huckleberry Finn," which replaced the word nigger with slave, touched a nerve. Is the point to safeguard the innocent or to make us feel we are…

What Is Kinesiology? Historical and Philosophical Insights

ERIC Educational Resources Information Center

Twietmeyer, Gregg

2012-01-01

Twenty years ago Karl Newell suggested in "Quest" that the proper name for the field was "kinesiology" and that its proper subject was "physical activity." Yet, despite his success, for many the purpose of the field remains enigmatic. This has led to a lack of clarity in programs, as well as tensions between scientists and humanists in the field.…

Enigmatic Moisture Effects on Al2O3 Scale and TBC Adhesion

NASA Technical Reports Server (NTRS)

Smialek, James L.

2008-01-01

Alumina scale adhesion to high temperature alloys is known to be affected primarily by sulfur segregation and reactive element additions. However, adherent scales can become partially compromised by excessive strain energy and cyclic cracking. With time, exposure of such scales to moisture can lead to spontaneous interfacial decohesion, occurring while the samples are maintained at ambient conditions. Examples of this Moisture-Induced Delayed Spallation (MIDS) are presented for NiCrAl and single crystal superalloys, becoming more severe with sulfur level and cyclic exposure conditions. Similarly, delayed failure or Desk Top Spallation (DTS) results are reviewed for thermal barrier coatings (TBCs), culminating in the water drop failure test. Both phenomena are discussed in terms of moisture effects on bulk alumina and bulk aluminides. A mechanism is proposed based on hydrogen embrittlement and is supported by a cathodic hydrogen charging experiment. Hydroxylation of aluminum from the alloy interface appears to be the relevant basic reaction.

Enigmatic Moisture Effects on Al2O3 Scale and TBC Adhesion

NASA Technical Reports Server (NTRS)

Smialek, James L.

2008-01-01

Alumina scale adhesion to high temperature alloys is known to be affected primarily by sulfur segregation and reactive element additions. However adherent scales can become partially compromised by excessive strain energy and cyclic cracking. With time, exposure of such scales to moisture can lead to spontaneous interfacial decohesion, occurring while the samples are maintained at ambient conditions. Examples of this Moisture-Induced Delayed Spallation (MIDS) are presented for NiCrAl and single crystal superalloys, becoming more severe with sulfur level and cyclic exposure conditions. Similarly, delayed failure or Desk Top Spallation (DTS) results are reviewed for TBC s, culminating in the water drop failure test. Both phenomena are discussed in terms of moisture effects on bulk alumina and bulk aluminides. A mechanism is proposed based on hydrogen embrittlement and is supported by a cathodic hydrogen charging experiment. Hydroxylation of aluminum from the alloy interface appears to be the relevant basic reaction.

INTEGRAL Observations of the Enigmatic Be Stars (gamma) Cassiopeiae and HD 110432

NASA Technical Reports Server (NTRS)

Sturner, S. J.; Shrader, C. R.

2007-01-01

We present the results of a hard X-ray study of the Be stars gamma Cassiopeiae and HD 110432 based on observations made with the INTEGRAL observatory. These stars are known to be moderately strong, X-ray sources (L(sub x) approx. equal to = 10(sup 32)-10(sup 33) erg per second). These values are at the extreme high end of the known luminosity distribution for active coronal systems, but several orders of magnitude below typical X-ray binaries. The hard X-ray spectra for these systems are quite similar. They can be well fitted by either optically thin thermal plasma models with kT = 12.5 - 14 keV or a cutoff powerlaw + gaussian line model with photon indices in the 1.3 - 1.5 range and a line energy of 6.7 keV. The 20-50 keV light curves show no evidence for flaring and no significant evidence for periodic variability. It has been proposed that the X-ray emission is due to either accretion onto a white dwarf companion or magnetic activity near the surface of the Be star. We discuss in detail the pros and cons of each scenario towards explaining our spectral and temporal results. Given that both thermal and nonthermal models fit the data equally well, we cannot use the spectra to delineate between these two scenarios. Recent observations indicate that gamma Cas has a approx. 1 solar mass companion in a 203.59 day orbit. This is consistent with the white dwarf - Be star binary model but the lack of periodic modulation of the flux on this timescale calls this conclusion into question. On the other hand the lack of flaring activity may rule against the magnetic activity model. We discuss advances in observations and theory that need to be made to resolve the origin of these systems.

On the enigmatic birth of the Pacific Plate within the Panthalassa Ocean

PubMed Central

Boschman, Lydian M.; van Hinsbergen, Douwe J. J.

2016-01-01

The oceanic Pacific Plate started forming in Early Jurassic time within the vast Panthalassa Ocean that surrounded the supercontinent Pangea, and contains the oldest lithosphere that can directly constrain the geodynamic history of the circum-Pangean Earth. We show that the geometry of the oldest marine magnetic anomalies of the Pacific Plate attests to a unique plate kinematic event that sparked the plate’s birth at virtually a point location, surrounded by the Izanagi, Farallon, and Phoenix Plates. We reconstruct the unstable triple junction that caused the plate reorganization, which led to the birth of the Pacific Plate, and present a model of the plate tectonic configuration that preconditioned this event. We show that a stable but migrating triple junction involving the gradual cessation of intraoceanic Panthalassa subduction culminated in the formation of an unstable transform-transform-transform triple junction. The consequent plate boundary reorganization resulted in the formation of a stable triangular three-ridge system from which the nascent Pacific Plate expanded. We link the birth of the Pacific Plate to the regional termination of intra-Panthalassa subduction. Remnants thereof have been identified in the deep lower mantle of which the locations may provide paleolongitudinal control on the absolute location of the early Pacific Plate. Our results constitute an essential step in unraveling the plate tectonic evolution of “Thalassa Incognita” that comprises the comprehensive Panthalassa Ocean surrounding Pangea. PMID:29713683

A mitogenomic timetree for Darwin’s enigmatic South American mammal Macrauchenia patachonica

PubMed Central

Westbury, Michael; Baleka, Sina; Barlow, Axel; Hartmann, Stefanie; Paijmans, Johanna L.A.; Kramarz, Alejandro; Forasiepi, Analía M; Bond, Mariano; Gelfo, Javier N.; Reguero, Marcelo A.; López-Mendoza, Patricio; Taglioretti, Matias; Scaglia, Fernando; Rinderknecht, Andrés; Jones, Washington; Mena, Francisco; Billet, Guillaume; de Muizon, Christian; Aguilar, José Luis; MacPhee, Ross D.E.; Hofreiter, Michael

2017-01-01

The unusual mix of morphological traits displayed by extinct South American native ungulates (SANUs) confounded both Charles Darwin, who first discovered them, and Richard Owen, who tried to resolve their relationships. Here we report an almost complete mitochondrial genome for the litoptern Macrauchenia. Our dated phylogenetic tree places Macrauchenia as sister to Perissodactyla, but close to the radiation of major lineages within Laurasiatheria. This position is consistent with a divergence estimate of ∼66 Ma (95% credibility interval, 56.64–77.83 Ma) obtained for the split between Macrauchenia and other Panperissodactyla. Combined with their morphological distinctiveness, this evidence supports the positioning of Litopterna (possibly in company with other SANU groups) as a separate order within Laurasiatheria. We also show that, when using strict criteria, extinct taxa marked by deep divergence times and a lack of close living relatives may still be amenable to palaeogenomic analysis through iterative mapping against more distant relatives. PMID:28654082

Modelling the enigmatic Late Pliocene Glacial Event - Marine Isotope Stage M2

USGS Publications Warehouse

Dolan, Aisling M.; Haywood, Alan M.; Hunter, Stephen J.; Tindall, Julia C.; Dowsett, Harry J.; Hill, Daniel J.; Pickering, Steven J.

2015-01-01

The Pliocene Epoch (5.2 to 2.58 Ma) has often been targeted to investigate the nature of warm climates. However, climate records for the Pliocene exhibit significant variability and show intervals that apparently experienced a cooler than modern climate. Marine Isotope Stage (MIS) M2 (~ 3.3 Ma) is a globally recognisable cooling event that disturbs an otherwise relatively (compared to present-day) warm background climate state. It remains unclear whether this event corresponds to significant ice sheet build-up in the Northern and Southern Hemisphere. Estimates of sea level for this interval vary, and range from modern values to estimates of 65 m sea level fall with respect to present day. Here we implement plausible M2 ice sheet configurations into a coupled atmosphere–ocean climate model to test the hypothesis that larger-than-modern ice sheet configurations may have existed at M2. Climate model results are compared with proxy climate data available for M2 to assess the plausibility of each ice sheet configuration. Whilst the outcomes of our data/model comparisons are not in all cases straight forward to interpret, there is little indication that results from model simulations in which significant ice masses have been prescribed in the Northern Hemisphere are incompatible with proxy data from the North Atlantic, Northeast Arctic Russia, North Africa and the Southern Ocean. Therefore, our model results do not preclude the possibility of the existence of larger ice masses during M2 in the Northern or Southern Hemisphere. Specifically they are not able to discount the possibility of significant ice masses in the Northern Hemisphere during the M2 event, consistent with a global sea-level fall of between 40 m and 60 m. This study highlights the general need for more focused and coordinated data generation in the future to improve the coverage and consistency in proxy records for M2, which will allow these and future M2 sensitivity tests to be interrogated further.

A very rare case of bloody tears with enigmatic epistaxis and haematuria.

PubMed

Ho, Jason Z S; de Silva, Julian; Olver, Jane

2011-03-01

Bloody tears are a rare symptom that can be caused by local or systemic pathology. We describe a very rare case of bloody tears that resulted from hyperthyroidism. A 15-year-old female patient presented with a 6-month history of bloody tears and epistaxis. Examination excluded local ocular and nasal pathology, including neoplasm and coagulopathy. Systemic investigations identified elevated thyroid function and following treatment her symptoms resolved. We discuss the mechanism by which hyperthyroidism may induce haemostatic dysfunction. We present the first case of bloody tears secondary to thyroid dysfunction.

The Paleoecology, Habitats, and Stratigraphic Range of the Enigmatic Cretaceous Brachiopod Peregrinella

PubMed Central

Kiel, Steffen; Glodny, Johannes; Birgel, Daniel; Bulot, Luc G.; Campbell, Kathleen A.; Gaillard, Christian; Graziano, Roberto; Kaim, Andrzej; Lazăr, Iuliana; Sandy, Michael R.; Peckmann, Jörn

2014-01-01

Modern and Cenozoic deep-sea hydrothermal-vent and methane-seep communities are dominated by large tubeworms, bivalves and gastropods. In contrast, many Early Cretaceous seep communities were dominated by the largest Mesozoic rhynchonellid brachiopod, the dimerelloid Peregrinella, the paleoecologic and evolutionary traits of which are still poorly understood. We investigated the nature of Peregrinella based on 11 occurrences world wide and a literature survey. All in situ occurrences of Peregrinella were confirmed as methane-seep deposits, supporting the view that Peregrinella lived exclusively at methane seeps. Strontium isotope stratigraphy indicates that Peregrinella originated in the late Berriasian and disappeared after the early Hauterivian, giving it a geologic range of ca. 9.0 (+1.45/–0.85) million years. This range is similar to that of rhynchonellid brachiopod genera in general, and in this respect Peregrinella differs from seep-inhabiting mollusks, which have, on average, longer geologic ranges than marine mollusks in general. Furthermore, we found that (1) Peregrinella grew to larger sizes at passive continental margins than at active margins; (2) it grew to larger sizes at sites with diffusive seepage than at sites with advective fluid flow; (3) despite its commonly huge numerical abundance, its presence had no discernible impact on the diversity of other taxa at seep sites, including infaunal chemosymbiotic bivalves; and (4) neither its appearance nor its extinction coincides with those of other seep-restricted taxa or with global extinction events during the late Mesozoic. A preference of Peregrinella for diffusive seepage is inferred from the larger average sizes of Peregrinella at sites with more microcrystalline carbonate (micrite) and less seep cements. Because other seep-inhabiting brachiopods occur at sites where such cements are very abundant, we speculate that the various vent- and seep-inhabiting dimerelloid brachiopods since Devonian time may have adapted to these environments in more than one way. PMID:25296341

On the Enigmatic Birth of the Pacific Plate within the Panthalassa Ocean

NASA Astrophysics Data System (ADS)

Boschman, L.; Van Hinsbergen, D. J. J.

2016-12-01

The oceanic Pacific Plate started forming in Early Jurassic time within the vast Panthalassa Ocean that surrounded the supercontinent Pangea and contains the oldest lithosphere that can directly constrain the geodynamic history of the circum-Pangean Earth. Here, we show that the geometry of the oldest marine magnetic anomalies of the Pacific Plate attests of a unique plate kinematic event that sparked the plate's birth in virtually a point location, surrounded by the Izanagi, Farallon and Phoenix Plates. We reconstruct the unstable triple junction that caused the plate reorganization leading to the birth of the Pacific Plate and present a model of the plate tectonic configuration that preconditioned this event. We show that a stable, but migrating triple junction involving the gradual cessation of intra-oceanic Panthalassa subduction culminated in the formation of an unstable transform-transform-transform triple junction. The consequent plate boundary reorganization resulted in the formation of a stable triangular three-ridge system from which the nascent Pacific Plate expanded. We link the birth of the Pacific Plate to the regional termination of intra-Panthalassa subduction. Remnants thereof have been identified in the deep lower mantle of which the locations may provide paleolongitudinal control on the absolute location of the early Pacific Plate. Our results constitute an essential step in unraveling the plate tectonic evolution of `Thalassa Incognita' comprising the comprehensive Panthalassa Ocean surrounding Pangea.

The Rovuma Transform Margin: the enigmatic continent-ocean boundary of East Africa

NASA Astrophysics Data System (ADS)

Phethean, Jordan; Kalnins, Lara; van Hunen, Jeroen; McCaffrey, Ken; Davies, Richard

2017-04-01

The N-S trending Davie Fracture Zone (DFZ) is often assumed to form the continent-ocean transform margin (COTM) of the Western Somali Basin. However, multiple plate tectonic reconstructions favour a pre-breakup location for Madagascar that crosses the DFZ, incompatible with its interpretation as the COTM (e.g., Lottes & Rowley, 1990; Reeves, 2014; Phethean et al., 2016). For the first time, we have identified classic COTM features in seismic reflection data from the Southern Rovuma Basin, to the west and inboard of the DFZ. These suggest a NNW trend to the margin, consistent with the tectonic reconstructions. 2D gravity models, with the seabed and top basement constrained by seismic data, are used to investigate the Moho structure across the Rovuma margin and are best fit using steep 'transform style' geometries, confirming the nature of the margin. We thus model generic COTM geometries elsewhere along the East African and Madagascan transform margins to locate best-fitting positions for these conjugate COTMs. This analysis confirms that the COTMs follow a NNW trend along the Rovuma Basin and Southern Madagascar, respectively, and allows a restoration of the conjugate COTMs. This restoration is used alongside geological maps and satellite imagery from Madagascar and East Africa to refine early plate motions and further constrain the precise origin of Madagascar within Gondwana. Our refined plate tectonic model independently predicts major observations made from seismic reflection and gravity data across the basin, including: regions of major transpression/transtension along the DFZ, merging of fracture zones to form the DFZ, oceanic crust on either side of the DFZ and within the Tanzania coastal basin, and the location of an abandoned MOR within the Tanzania coastal basin. We believe that this study finally provides conclusive evidence that Madagascar originated from within the Tanzania Coastal Basin, inboard of the DFZ, after some 30 years of debate regarding this matter. Lottes, A.L., Rowley, D.B., 1990. Reconstruction of the Laurasian and Gondwanan segments of Permian Pangea. Geol. Soc. London Mem., 12, 383-395. Reeves, C., 2014. The position of Madagascar within Gondwana and its movements during Gondwana dispersal. J. Afr. Earth Sci., 94, 45-57. Phethean, J.J.J., Kalnins, L.M., van Hunen, J.,Biffi, P.G., Davies, R.J., McCaffrey, K.J.W., 2016. Madagascar's escape from Africa: A high-resolution plate reconstruction for the Western Somali Basin and implications for supercontinent dispersal. Geochem. Geophys. Geosyst., 17, doi:10.1002/2016GC006624.

An enigmatic plant-eating theropod from the Late Jurassic period of Chile.

PubMed

Novas, Fernando E; Salgado, Leonardo; Suárez, Manuel; Agnolín, Federico L; Ezcurra, Martín D; Chimento, Nicolás R; de la Cruz, Rita; Isasi, Marcelo P; Vargas, Alexander O; Rubilar-Rogers, David

2015-06-18

Theropod dinosaurs were the dominant predators in most Mesozoic era terrestrial ecosystems. Early theropod evolution is currently interpreted as the diversification of various carnivorous and cursorial taxa, whereas the acquisition of herbivorism, together with the secondary loss of cursorial adaptations, occurred much later among advanced coelurosaurian theropods. A new, bizarre herbivorous basal tetanuran from the Upper Jurassic of Chile challenges this conception. The new dinosaur was discovered at Aysén, a fossil locality in the Upper Jurassic Toqui Formation of southern Chile (General Carrera Lake). The site yielded abundant and exquisitely preserved three-dimensional skeletons of small archosaurs. Several articulated individuals of Chilesaurus at different ontogenetic stages have been collected, as well as less abundant basal crocodyliforms, and fragmentary remains of sauropod dinosaurs (diplodocids and titanosaurians).

Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria

PubMed Central

2008-01-01

Background Polypodium hydriforme is a parasite with an unusual life cycle and peculiar morphology, both of which have made its systematic position uncertain. Polypodium has traditionally been considered a cnidarian because it possesses nematocysts, the stinging structures characteristic of this phylum. However, recent molecular phylogenetic studies using 18S rDNA sequence data have challenged this interpretation, and have shown that Polypodium is a close relative to myxozoans and together they share a closer affinity to bilaterians than cnidarians. Due to the variable rates of 18S rDNA sequences, these results have been suggested to be an artifact of long-branch attraction (LBA). A recent study, using multiple protein coding markers, shows that the myxozoan Buddenbrockia, is nested within cnidarians. Polypodium was not included in this study. To further investigate the phylogenetic placement of Polypodium, we have performed phylogenetic analyses of metazoans with 18S and partial 28S rDNA sequences in a large dataset that includes Polypodium and a comprehensive sampling of cnidarian taxa. Results Analyses of a combined dataset of 18S and partial 28S sequences, and partial 28S alone, support the placement of Polypodium within Cnidaria. Removal of the long-branched myxozoans from the 18S dataset also results in Polypodium being nested within Cnidaria. These results suggest that previous reports showing that Polypodium and Myxozoa form a sister group to Bilateria were an artifact of long-branch attraction. Conclusion By including 28S rDNA sequences and a comprehensive sampling of cnidarian taxa, we demonstrate that previously conflicting hypotheses concerning the phylogenetic placement of Polypodium can be reconciled. Specifically, the data presented provide evidence that Polypodium is indeed a cnidarian and is either the sister taxon to Hydrozoa, or part of the hydrozoan clade, Leptothecata. The former hypothesis is consistent with the traditional view that Polypodium should be placed in its own cnidarian class, Polypodiozoa. PMID:18471296

Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria.

PubMed

Evans, Nathaniel M; Lindner, Alberto; Raikova, Ekaterina V; Collins, Allen G; Cartwright, Paulyn

2008-05-09

Polypodium hydriforme is a parasite with an unusual life cycle and peculiar morphology, both of which have made its systematic position uncertain. Polypodium has traditionally been considered a cnidarian because it possesses nematocysts, the stinging structures characteristic of this phylum. However, recent molecular phylogenetic studies using 18S rDNA sequence data have challenged this interpretation, and have shown that Polypodium is a close relative to myxozoans and together they share a closer affinity to bilaterians than cnidarians. Due to the variable rates of 18S rDNA sequences, these results have been suggested to be an artifact of long-branch attraction (LBA). A recent study, using multiple protein coding markers, shows that the myxozoan Buddenbrockia, is nested within cnidarians. Polypodium was not included in this study. To further investigate the phylogenetic placement of Polypodium, we have performed phylogenetic analyses of metazoans with 18S and partial 28S rDNA sequences in a large dataset that includes Polypodium and a comprehensive sampling of cnidarian taxa. Analyses of a combined dataset of 18S and partial 28S sequences, and partial 28S alone, support the placement of Polypodium within Cnidaria. Removal of the long-branched myxozoans from the 18S dataset also results in Polypodium being nested within Cnidaria. These results suggest that previous reports showing that Polypodium and Myxozoa form a sister group to Bilateria were an artifact of long-branch attraction. By including 28S rDNA sequences and a comprehensive sampling of cnidarian taxa, we demonstrate that previously conflicting hypotheses concerning the phylogenetic placement of Polypodium can be reconciled. Specifically, the data presented provide evidence that Polypodium is indeed a cnidarian and is either the sister taxon to Hydrozoa, or part of the hydrozoan clade, Leptothecata. The former hypothesis is consistent with the traditional view that Polypodium should be placed in its own cnidarian class, Polypodiozoa.

BRITE-Constellation reveals evidence for pulsations in the enigmatic binary η Carinae

NASA Astrophysics Data System (ADS)

Richardson, Noel D.; Pablo, Herbert; Sterken, Christiaan; Pigulski, Andrzej; Koenigsberger, Gloria; Moffat, Anthony F. J.; Madura, Thomas I.; Hamaguchi, Kenji; Corcoran, Michael F.; Damineli, Augusto; Gull, Theodore R.; Hillier, D. John; Weigelt, Gerd; Handler, Gerald; Popowicz, Adam; Wade, Gregg A.; Weiss, Werner W.; Zwintz, Konstanze

2018-04-01

η Car is a massive, eccentric binary with a rich observational history. We obtained the first high-cadence, high-precision light curves with the BRITE-Constellation nanosatellites over 6 months in 2016 and 6 months in 2017. The light curve is contaminated by several sources including the Homunculus nebula and neighbouring stars, including the eclipsing binary CPD -59°2628. However, we found two coherent oscillations in the light curve. These may represent pulsations that are not yet understood but we postulate that they are related to tidally excited oscillations of η Car's primary star, and would be similar to those detected in lower mass eccentric binaries. In particular, one frequency was previously detected by van Genderen et al. and Sterken et al. through the time period of 1974-1995 through timing measurements of photometric maxima. Thus, this frequency seems to have been detected for nearly four decades, indicating that it has been stable in frequency over this time span. These pulsations could help provide the first direct constraints on the fundamental parameters of the primary star if confirmed and refined with future observations.

The Nature of the Enigmatic 10-Minute Accreting Binary System ES CET

NASA Technical Reports Server (NTRS)

Steeghs, Daniel

2005-01-01

ES Cet is one of the most compact binary systems known with an orbital period of only 10.3 minutes. Our allocated observations with the XMM-Newton X-ray satellite were performed in January and July 2004, with the data being delivered to the PI in August 2004. Preliminary results were presented by the PI in September 2004 and January 2005. We have also secured supporting optical observations of ES Ceti using the Magellan telescopes (November 2004). The team is currently performing a thorough and final analysis of the X-ray, UV and optical data sets with the latest XMM pipeline software and our own analysis packages.

Enigmatic diamonds in Archean calc-alkaline lamprophyres of Wawa, southern Ontario, Canada

NASA Astrophysics Data System (ADS)

de Stefano, Andrea; Lefebvre, Nathalie; Kopylova, Maya

2006-02-01

A suite of 80 macrodiamonds recovered from volcaniclastic breccia of Wawa (southern Ontario) was characterized on the basis of morphology, nitrogen content and aggregation, cathodoluminescence (CL), and mineral inclusions. The host calc-alkaline lamprophyric breccias were emplaced at 2.68-2.74 Ga, contemporaneously with voluminous bimodal volcanism of the Michipicoten greenstone belt. The studied suite of diamonds differs from the vast majority of diamond suites found worldwide. First, the suite is hosted by calc-alkaline lamprophyric volcanics rather than by kimberlite or lamproite. Second, the host volcanic rock is amongst the oldest known diamondiferous rocks on Earth, and has experienced regional metamorphism and deformation. Finally, most diamonds show yellow-orange-red CL and contain mineral inclusions not in equilibrium with each other or their host diamond. The majority of the diamonds in the Wawa suite are colorless, weakly resorbed, octahedral single crystals and aggregates. The diamonds contain 0-740 ppm N and show two modes of N aggregation at 0-30 and 60-95% B-centers suggesting mantle storage at 1,100-1,170°C. Cathodoluminescence and FTIR spectroscopy shows that emission peaks present in orange CL stones do not likely result from irradiation or single substitutional N, in contrast to other diamonds with red CL. The diamonds contain primary inclusions of olivine (Fo92 and Fo89), omphacite, orthopyroxene (En93), pentlandite, albite, and An-rich plagioclase. These peridotitic and eclogitic minerals are commonly found within single diamonds in a mixed paragenesis which also combines shallow and deep phases. This apparent disequilibrium can be explained by effective small-scale mixing of subducted oceanic crust and mantle rocks in fast “cold” plumes ascending from the top of the slabs in convergent margins. Alternatively, the diamonds could have formed in the pre-2.7-2.9 Ga cratonic mantle and experienced subsequent alteration of syngenetic inclusions related to host magmatism and ensuing metamorphism. Neither orogenic nor cratonic model of the diamond origin fully explains all of the observed characteristics of the diamonds and their host rocks.

On the enigmatic birth of the Pacific Plate within the Panthalassa Ocean.

PubMed

Boschman, Lydian M; van Hinsbergen, Douwe J J

2016-07-01

The oceanic Pacific Plate started forming in Early Jurassic time within the vast Panthalassa Ocean that surrounded the supercontinent Pangea, and contains the oldest lithosphere that can directly constrain the geodynamic history of the circum-Pangean Earth. We show that the geometry of the oldest marine magnetic anomalies of the Pacific Plate attests to a unique plate kinematic event that sparked the plate's birth at virtually a point location, surrounded by the Izanagi, Farallon, and Phoenix Plates. We reconstruct the unstable triple junction that caused the plate reorganization, which led to the birth of the Pacific Plate, and present a model of the plate tectonic configuration that preconditioned this event. We show that a stable but migrating triple junction involving the gradual cessation of intraoceanic Panthalassa subduction culminated in the formation of an unstable transform-transform-transform triple junction. The consequent plate boundary reorganization resulted in the formation of a stable triangular three-ridge system from which the nascent Pacific Plate expanded. We link the birth of the Pacific Plate to the regional termination of intra-Panthalassa subduction. Remnants thereof have been identified in the deep lower mantle of which the locations may provide paleolongitudinal control on the absolute location of the early Pacific Plate. Our results constitute an essential step in unraveling the plate tectonic evolution of "Thalassa Incognita" that comprises the comprehensive Panthalassa Ocean surrounding Pangea.

Turning semicircular canal function on its head: dinosaurs and a novel vestibular analysis.

PubMed

Georgi, Justin A; Sipla, Justin S; Forster, Catherine A

2013-01-01

Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this method fails to discriminate bipedal from quadrupedal non-avian dinosaurs. Because they exhibit a broad range of relative head sizes, we use dinosaurs to test the hypothesis that semicircular ducts scale more closely with head size. Comparing the area enclosed by each semicircular canal to estimated body mass and to two different measures of head size, skull length and estimated head mass, reveals significant patterns that corroborate a connection between physical parameters of the head and semicircular canal morphology. Head mass more strongly correlates with anterior semicircular canal size than does body mass and statistically separates bipedal from quadrupedal taxa, with bipeds exhibiting relatively larger canals. This morphologic dichotomy likely reflects adaptations of the vestibular system to stability demands associated with terrestrial locomotion on two, versus four, feet. This new method has implications for reinterpreting previous studies and informing future studies on the connection between locomotion type and vestibular function.

Turning Semicircular Canal Function on Its Head: Dinosaurs and a Novel Vestibular Analysis

PubMed Central

Georgi, Justin A.; Sipla, Justin S.; Forster, Catherine A.

2013-01-01

Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this method fails to discriminate bipedal from quadrupedal non-avian dinosaurs. Because they exhibit a broad range of relative head sizes, we use dinosaurs to test the hypothesis that semicircular ducts scale more closely with head size. Comparing the area enclosed by each semicircular canal to estimated body mass and to two different measures of head size, skull length and estimated head mass, reveals significant patterns that corroborate a connection between physical parameters of the head and semicircular canal morphology. Head mass more strongly correlates with anterior semicircular canal size than does body mass and statistically separates bipedal from quadrupedal taxa, with bipeds exhibiting relatively larger canals. This morphologic dichotomy likely reflects adaptations of the vestibular system to stability demands associated with terrestrial locomotion on two, versus four, feet. This new method has implications for reinterpreting previous studies and informing future studies on the connection between locomotion type and vestibular function. PMID:23516495

Symmetry in locomotor central pattern generators and animal gaits

NASA Astrophysics Data System (ADS)

Golubitsky, Martin; Stewart, Ian; Buono, Pietro-Luciano; Collins, J. J.

1999-10-01

Animal locomotion is controlled, in part, by a central pattern generator (CPG), which is an intraspinal network of neurons capable of generating a rhythmic output. The spatio-temporal symmetries of the quadrupedal gaits walk, trot and pace lead to plausible assumptions about the symmetries of locomotor CPGs. These assumptions imply that the CPG of a quadruped should consist of eight nominally identical subcircuits, arranged in an essentially unique matter. Here we apply analogous arguments to myriapod CPGs. Analyses based on symmetry applied to these networks lead to testable predictions, including a distinction between primary and secondary gaits, the existence of a new primary gait called `jump', and the occurrence of half-integer wave numbers in myriapod gaits. For bipeds, our analysis also predicts two gaits with the out-of-phase symmetry of the walk and two gaits with the in-phase symmetry of the hop. We present data that support each of these predictions. This work suggests that symmetry can be used to infer a plausible class of CPG network architectures from observed patterns of animal gaits.

Orthotic Body-Weight Support Through Underactuated Potential Energy Shaping with Contact Constraints

PubMed Central

Lv, Ge; Gregg, Robert D.

2015-01-01

Body-weight support is an effective clinical tool for gait rehabilitation after neurological impairment. Body-weight supported training systems have been developed to help patients regain mobility and confidence during walking, but conventional systems constrain the patient's treatment in clinical environments. We propose that this challenge could be addressed by virtually providing patients with body-weight support through the actuators of a powered orthosis (or exoskeleton) utilizing potential energy shaping control. However, the changing contact conditions and degrees of underactuation encountered during human walking present significant challenges to consistently matching a desired potential energy for the human in closed loop. We therefore introduce a generalized matching condition for shaping Lagrangian systems with holonomic contact constraints. By satisfying this matching condition for four phases of gait, we derive control laws to achieve virtual body-weight support through a powered knee-ankle orthosis. We demonstrate beneficial effects of virtual body-weight support in simulations of a human-like biped model, indicating the potential clinical value of this proposed control approach. PMID:26900254

The metabolic cost of walking on an incline in the Peacock (Pavo cristatus).

PubMed

Wilkinson, Holly; Thavarajah, Nathan; Codd, Jonathan

2015-01-01

Altering speed and moving on a gradient can affect an animal's posture and gait, which in turn can change the energetic requirements of terrestrial locomotion. Here, the energetic and kinematic effects of locomoting on an incline were investigated in the Indian peacock, Pavo cristatus. The mass-specific metabolic rate of the Indian peacock was elevated on an incline, but this change was not dependent on the angle ascended and the cost of lifting remained similar between the two inclines (+5 and +7°). Interestingly, the Indian peacock had the highest efficiency when compared to any other previously studied avian biped, despite the presence of a large train. Duty factors were higher for birds moving on an incline, but there was no difference between +5 and +7°. Our results highlight the importance of investigating kinematic responses during energetic studies, as these may enable explanation of what is driving the underlying metabolic differences when moving on inclines. Further investigations are required to elucidate the underlying mechanical processes occurring during incline movement.

Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke.

PubMed

Nudds, Robert L; Dyke, Gareth J

2009-04-01

Ontogenetic and behavioral studies using birds currently do not document the early evolution of flight because birds (including juveniles) used in such studies employ forelimb oscillation frequencies over 10 Hz, forelimb stroke-angles in excess of 130 degrees , and possess uniquely avian flight musculatures. Living birds are an advanced morphological stage in the development of flapping flight. To gain insight into the early stages of flight evolution (i.e., prebird), in the absence of a living analogue, a new approach using Strouhal number was used. Strouhal number is a nondimensional number that describes the relationship between wing-stroke amplitude (A), wing-beat frequency (f), and flight speed (U). Calculations indicated that even moderate wing movements are enough to generate rudimentary thrust and that a propulsive flapping flight-stroke could have evolved via gradual incremental changes in wing movement and wing morphology. More fundamental to the origin of the avian flapping flight-stroke is the question of how a symmetrical forelimb posture-required for gliding and flapping flight-evolved from an alternating forelimb motion, evident in all extant bipeds when running except birds.

Reinforcement learning state estimator.

PubMed

Morimoto, Jun; Doya, Kenji

2007-03-01

In this study, we propose a novel use of reinforcement learning for estimating hidden variables and parameters of nonlinear dynamical systems. A critical issue in hidden-state estimation is that we cannot directly observe estimation errors. However, by defining errors of observable variables as a delayed penalty, we can apply a reinforcement learning frame-work to state estimation problems. Specifically, we derive a method to construct a nonlinear state estimator by finding an appropriate feedback input gain using the policy gradient method. We tested the proposed method on single pendulum dynamics and show that the joint angle variable could be successfully estimated by observing only the angular velocity, and vice versa. In addition, we show that we could acquire a state estimator for the pendulum swing-up task in which a swing-up controller is also acquired by reinforcement learning simultaneously. Furthermore, we demonstrate that it is possible to estimate the dynamics of the pendulum itself while the hidden variables are estimated in the pendulum swing-up task. Application of the proposed method to a two-linked biped model is also presented.

Controlling legs for locomotion-insights from robotics and neurobiology.

PubMed

Buschmann, Thomas; Ewald, Alexander; von Twickel, Arndt; Büschges, Ansgar

2015-06-29

Walking is the most common terrestrial form of locomotion in animals. Its great versatility and flexibility has led to many attempts at building walking machines with similar capabilities. The control of walking is an active research area both in neurobiology and robotics, with a large and growing body of work. This paper gives an overview of the current knowledge on the control of legged locomotion in animals and machines and attempts to give walking control researchers from biology and robotics an overview of the current knowledge in both fields. We try to summarize the knowledge on the neurobiological basis of walking control in animals, emphasizing common principles seen in different species. In a section on walking robots, we review common approaches to walking controller design with a slight emphasis on biped walking control. We show where parallels between robotic and neurobiological walking controllers exist and how robotics and biology may benefit from each other. Finally, we discuss where research in the two fields diverges and suggest ways to bridge these gaps.

A bipedal DNA Brownian motor with coordinated legs.

PubMed

Omabegho, Tosan; Sha, Ruojie; Seeman, Nadrian C

2009-04-03

A substantial challenge in engineering molecular motors is designing mechanisms to coordinate the motion between multiple domains of the motor so as to bias random thermal motion. For bipedal motors, this challenge takes the form of coordinating the movement of the biped's legs so that they can move in a synchronized fashion. To address this problem, we have constructed an autonomous DNA bipedal walker that coordinates the action of its two legs by cyclically catalyzing the hybridization of metastable DNA fuel strands. This process leads to a chemically ratcheted walk along a directionally polar DNA track. By covalently cross-linking aliquots of the walker to its track in successive walking states, we demonstrate that this Brownian motor can complete a full walking cycle on a track whose length could be extended for longer walks. We believe that this study helps to uncover principles behind the design of unidirectional devices that can function without intervention. This device should be able to fulfill roles that entail the performance of useful mechanical work on the nanometer scale.

Does trampolining and anaerobic physical fitness affect sleep?

PubMed

Buchegger, J; Fritsch, R; Meier-Koll, A; Riehle, H

1991-08-01

The structure of nocturnal sleep of 16 volunteers, participating in the anaerobic sports of trampolining, dancing, and soccer, was monitored by means of polygraphic recordings. Since trampolining requires the acquisition of unfamiliar patterns of motor coordination, it can be considered as a special form of motor learning, whereas the acquisition of motor skills specific for dancing and soccer can be linked with motor patterns of normal biped locomotion. According to this view, an experimental group of 8 volunteers was formed; they participated in a training course of trampolining. In addition, a control group of 8 subjects was recruited, who engaged in one of the other two anaerobic sports. Subjects who had acquired new motor skills during a 13-wk. program in trampolining showed a statistically significant increase in REM-sleep. By contrast, the 8 subjects of the control group showed no considerable changes in REM-sleep. This suggests that efforts in acquiring new and complex motor patterns activate processes specifically involved in the generation of REM stage during nocturnal sleep.

Sequential divergence and the multiplicative origin of community diversity

PubMed Central

Hood, Glen R.; Forbes, Andrew A.; Powell, Thomas H. Q.; Egan, Scott P.; Hamerlinck, Gabriela; Smith, James J.; Feder, Jeffrey L.

2015-01-01

Phenotypic and genetic variation in one species can influence the composition of interacting organisms within communities and across ecosystems. As a result, the divergence of one species may not be an isolated process, as the origin of one taxon could create new niche opportunities for other species to exploit, leading to the genesis of many new taxa in a process termed “sequential divergence.” Here, we test for such a multiplicative effect of sequential divergence in a community of host-specific parasitoid wasps, Diachasma alloeum, Utetes canaliculatus, and Diachasmimorpha mellea (Hymenoptera: Braconidae), that attack Rhagoletis pomonella fruit flies (Diptera: Tephritidae). Flies in the R. pomonella species complex radiated by sympatrically shifting and ecologically adapting to new host plants, the most recent example being the apple-infesting host race of R. pomonella formed via a host plant shift from hawthorn-infesting flies within the last 160 y. Using population genetics, field-based behavioral observations, host fruit odor discrimination assays, and analyses of life history timing, we show that the same host-related ecological selection pressures that differentially adapt and reproductively isolate Rhagoletis to their respective host plants (host-associated differences in the timing of adult eclosion, host fruit odor preference and avoidance behaviors, and mating site fidelity) cascade through the ecosystem and induce host-associated genetic divergence for each of the three members of the parasitoid community. Thus, divergent selection at lower trophic levels can potentially multiplicatively and rapidly amplify biodiversity at higher levels on an ecological time scale, which may sequentially contribute to the rich diversity of life. PMID:26499247

The “Neuro” of Neuroblastoma: Neuroblastoma as a Neurodevelopmental Disorder

PubMed Central

Ratner, Nancy; Brodeur, Garrett M.; Dale, Russell C.; Schor, Nina F.

2017-01-01

Neuroblastoma is a childhood cancer derived from cells of neural crest origin. The hallmarks of its enigmatic character include its propensity for spontaneous regression under some circumstances and its association with paraneoplastic opsoclonus, myoclonus, and ataxia. The neurodevelopmental underpinnings of its origins may provide important clues for development of novel therapeutic and preventive agents for this frequently fatal malignancy and for the associated paraneoplastic syndromes. PMID:27043043

Microbiome-on-a-Chip: New Frontiers in Plant-Microbiota Research.

PubMed

Stanley, Claire E; van der Heijden, Marcel G A

2017-08-01

An enigmatic concoction of interactions between microbes and hosts takes place below ground, yet the function(s) of the individual components in this complex playground are far from understood. This Forum article highlights how microfluidic - or 'Microbiome-on-a-Chip' - technology could help to shed light on such relationships, opening new frontiers in plant-microbiota research. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gods behaving badly.

PubMed

Retsas, Spyros

2015-02-01

This paper addresses the myths surrounding the birth and death of Asclepios, the popular healing God of the Greeks and his place among other deities of the Greek Pantheon. The enigmatic invocation of Asclepios by Socrates, the Athenian philosopher condemned to take the hemlock, in his final moments is also discussed. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Evidence for Trivelpiece-Gould modes in a helicon discharge.

PubMed

Blackwell, D D; Madziwa, T G; Arnush, D; Chen, F F

2002-04-08

The high ionization efficiency of helicon discharges has been attributed to Landau damping and mode coupling to Trivelpiece-Gould (TG) modes. Though theory predicts the importance of TG modes, they have rarely been seen. Here they were detected directly by measuring their radiofrequency current with a J-dot probe, thus supporting the contention that TG modes play a role in these enigmatic plasma sources.

Nostradamus (1503-66)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Doctor, astrologer, born in St Rémy, France. Took on the role of a prophet and wrote Centuries, a collection of predictions in rhyme (1555-8). The predictions are expressed in obscure and enigmatic terms, which are both difficult to interpret and open to many interpretations, and so can be interpreted as successful prophesies, including what Catherine of Medici interpreted as the manner of deat...

Pure spin current and phonon thermoelectric transport in a triangulene-based molecular junction.

PubMed

Wang, Qiang; Li, Jianwei; Nie, Yihang; Xu, Fuming; Yu, Yunjin; Wang, Bin

2018-06-13

The experimental synthesis and characterization of enigmatic triangulene were reported for the first time recently. Based on this enigmatic molecule, we proposed a triangulene-based molecular junction and presented first principles calculations to investigate the electron and phonon thermoelectric transport properties. Numerical results show that the spin polarized electric transport properties of the triangulene-based molecular junction can be adjusted effectively by bias voltage and gate voltage. Through varying the gate voltage applied on the triangulene molecule, the system can exhibit a perfect spin filter effect. When a temperature gradient is applied between the two leads, spin up current and spin down current flow along opposite directions in the system simultaneously. Thus pure spin current can be obtained on a large scale by changing the temperature, temperature gradient, and gate voltage. When the phonon vibration effect is considered in thermal transport, the figure of merit is suppressed distinctively especially when the temperature is within the 10 K < T < 100 K range. More importantly, a large spin figure of merit can be achieved accompanied by a small charge figure of merit by adjusting the temperature, gate voltage and chemical potential in a wide range, which indicates a favorable application prospect of the triangulene-based molecular junction as a spin calorigenic device.

Toward a comprehensive understanding of phylogenetic relationships among lineages of Acanthaceae s.l. (Lamiales).

PubMed

McDade, Lucinda A; Daniel, Thomas F; Kiel, Carrie A

2008-09-01

Acanthaceae (Asteridae; Lamiales) include ∼4000 species and encompass a range of morphological diversity, habitats, and biogeographic patterns. Although they are important components of tropical and subtropical habitats worldwide, inadequate knowledge of the family's phylogenetic framework has impeded comparative research. In this study, we sampled all known lineages of Acanthaceae including Andrographideae. Also included were eight of 13 genera whose relationships remain enigmatic. We used sequence data from nrITS and four chloroplast noncoding regions, and parsimony and Bayesian methods of analysis. Results strongly support most aspects of relationships including inclusion of Avicennia in Acanthaceae. Excepting Neuracanthus, newly sampled taxa are placed with strong support; Kudoacanthus is in Justicieae, Tetramerium lineage, and the remaining enigmatic genera are in Whitfieldieae or Barlerieae, and Andrographideae are sister to Barlerieae. This last result is unanticipated, but placement of Andrographideae based on structural characters has been elusive. Neuracanthus is monophyletic but placement relative to (Whitfieldieae (Andrographideae + Barlerieae)) is weakly supported. Many clades have clear morphological synapomorphies, but nonmolecular evidence for some remains elusive. Results suggest an Old World origin with multiple dispersal events to the New World. This study informs future work by clarifying sampling strategy and identifying aspects of relationships that require further study.

Global warming and ocean acidification through halted weathering feedback during the Middle Eocene Climatic Optimum

NASA Astrophysics Data System (ADS)

van der Ploeg, R.; Selby, D. S.; Cramwinckel, M.; Bohaty, S. M.; Sluijs, A.; Middelburg, J. J.

2016-12-01

The Middle Eocene Climatic Optimum (MECO) represents a 500 kyr period of global warming 40 million years ago associated with a rise in atmospheric CO2 concentrations, but its cause remains enigmatic. Moreover, on the timescale of the MECO, an increase in silicate weathering rates on the continents is expected to balance carbon input and restore the alkalinity of the oceans, but this is in sharp disagreement with observations of extensive carbonate dissolution. Here we show, based on osmium isotope ratios of marine sediments from three different sites, that CO2 rise and warming did not lead to enhanced continental weathering during the MECO, in contrast to expectations from carbon cycle theory. Remarkably, a minor shift to lower, more unradiogenic osmium isotope ratios rather indicates an episode of increased volcanism or reduced continental weathering. This disproves silicate weathering as a geologically constant feedback to CO2 variations. Rather, we suggest that global Early and Middle Eocene warmth diminished the weatherability of continental rocks, ultimately leading to CO2 accumulation during the MECO, and show the plausibility of this scenario using carbon cycle modeling simulations. We surmise a dynamic weathering feedback might explain multiple enigmatic phases of coupled climate and carbon cycle change in the Cretaceous and Cenozoic.

Exploring microbial dark matter to resolve the deep archaeal ancestry of eukaryotes

DOE PAGES

Saw, Jimmy H.; Spang, Anja; Zaremba-Niedzwiedzka, Katarzyna; ...

2015-08-31

The origin of eukaryotes represents an enigmatic puzzle, which is still lacking a number of essential pieces. Whereas it is currently accepted that the process of eukaryogenesis involved an interplay between a host cell and an alphaproteobacterial endosymbiont, we currently lack detailed information regarding the identity and nature of these players. A number of studies have provided increasing support for the emergence of the eukaryotic host cell from within the archaeal domain of life, displaying a specific affiliation with the archaeal TACK superphylum. Recent studies have shown that genomic exploration of yet-uncultivated archaea, the so-called archaeal 'dark matter', is ablemore » to provide unprecedented insights into the process of eukaryogenesis. Here, we provide an overview of state-of-the-art cultivation-independent approaches, and demonstrate how these methods were used to obtain draft genome sequences of several novel members of the TACK superphylum, including Lokiarchaeum, two representatives of the Miscellaneous Crenarchaeotal Group (Bathyarchaeota), and a Korarchaeum-related lineage. In conclusion, the maturation of cultivation-independent genomics approaches, as well as future developments in next-generation sequencing technologies, will revolutionize our current view of microbial evolution and diversity, and provide profound new insights into the early evolution of life, including the enigmatic origin of the eukaryotic cell.« less

Some surprising manifestations of charged particle dynamics in a magnetic field

NASA Astrophysics Data System (ADS)

Varma, Ram K.

2010-08-01

We present here some very unusual experimental results on the dynamics of charged particle in a magnetic field which cannot be comprehended in terms of the Lorentz dynamics regarded, as per the current conceptual framework, as the appropriate one for the macro-scale description. Astonishingly, these results have been shown to be manifestations of a novel macro-scale quantum structure, designated as ‘transition amplitude wave’ (TAW), riding with the guiding centre trajectory, which is generated in the latter trajectory in consequence of the scattering of the particle with a fixed scattering centre. One set of observed results is thus identified as matter wave interference effects on the macro-scale attributable to this entity. The other enigmatic observation demonstrates the detection of a curl-free magnetic vector potential on the macro-scale, which is also shown to be a consequence of the TAW embedded in the Lorentz trajectory. These enigmatic results thus point to the unravelling of a new concept of a ‘dressed’ Lorentz trajectory—dressed with the TAW—accountable for these results, as against the ‘bare’ trajectory. These results and the formalism which enables one to comprehend them have led to the emergence of a new class of phenomena which display quantum properties on the macro-scale.

Exploring microbial dark matter to resolve the deep archaeal ancestry of eukaryotes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saw, Jimmy H.; Spang, Anja; Zaremba-Niedzwiedzka, Katarzyna

The origin of eukaryotes represents an enigmatic puzzle, which is still lacking a number of essential pieces. Whereas it is currently accepted that the process of eukaryogenesis involved an interplay between a host cell and an alphaproteobacterial endosymbiont, we currently lack detailed information regarding the identity and nature of these players. A number of studies have provided increasing support for the emergence of the eukaryotic host cell from within the archaeal domain of life, displaying a specific affiliation with the archaeal TACK superphylum. Recent studies have shown that genomic exploration of yet-uncultivated archaea, the so-called archaeal 'dark matter', is ablemore » to provide unprecedented insights into the process of eukaryogenesis. Here, we provide an overview of state-of-the-art cultivation-independent approaches, and demonstrate how these methods were used to obtain draft genome sequences of several novel members of the TACK superphylum, including Lokiarchaeum, two representatives of the Miscellaneous Crenarchaeotal Group (Bathyarchaeota), and a Korarchaeum-related lineage. In conclusion, the maturation of cultivation-independent genomics approaches, as well as future developments in next-generation sequencing technologies, will revolutionize our current view of microbial evolution and diversity, and provide profound new insights into the early evolution of life, including the enigmatic origin of the eukaryotic cell.« less

North American import? Charting the origins of an enigmatic Trypanosoma cruzi domestic genotype.

PubMed

Zumaya-Estrada, Federico A; Messenger, Louisa A; Lopez-Ordonez, Teresa; Lewis, Michael D; Flores-Lopez, Carlos A; Martínez-Ibarra, Alejandro J; Pennington, Pamela M; Cordon-Rosales, Celia; Carrasco, Hernan V; Segovia, Maikel; Miles, Michael A; Llewellyn, Martin S

2012-10-10

Trypanosoma cruzi, the agent of Chagas disease, is currently recognized as a complex of six lineages or Discrete Typing Units (DTU): TcI-TcVI. Recent studies have identified a divergent group within TcI - TcI(DOM). TcI(DOM). is associated with a significant proportion of human TcI infections in South America, largely absent from local wild mammals and vectors, yet closely related to sylvatic strains in North/Central America. Our aim was to examine hypotheses describing the origin of the TcI(DOM) genotype. We propose two possible scenarios: an emergence of TcI(DOM) in northern South America as a sister group of North American strain progenitors and dispersal among domestic transmission cycles, or an origin in North America, prior to dispersal back into South American domestic cycles. To provide further insight we undertook high resolution nuclear and mitochondrial genotyping of multiple Central American strains (from areas of México and Guatemala) and included them in an analysis with other published data. Mitochondrial sequence and nuclear microsatellite data revealed a cline in genetic diversity across isolates grouped into three populations: South America, North/Central America and TcI(DOM). As such, greatest diversity was observed in South America (A(r) = 4.851, π = 0.00712) and lowest in TcI(DOM) (Ar = 1.813, π = 0.00071). Nuclear genetic clustering (genetic distance based) analyses suggest that TcI(DOM) is nested within the North/Central American clade. Declining genetic diversity across the populations, and corresponding hierarchical clustering suggest that emergence of this important human genotype most likely occurred in North/Central America before moving southwards. These data are consistent with early patterns of human dispersal into South America.

Enigmatic Extinction: An Investigation of the 2175Å Extinction Bump in M101

NASA Astrophysics Data System (ADS)

Danowski, Meredith E.; Cook, Timothy; Gordon, Karl D.; Chakrabarti, Supriya; Lawton, Brandon L.; Misselt, Karl A.

2014-06-01

Evidence from studies of starburst galaxies indicates that active formation of high mass stars modifies the UV dust extinction curve as seen by a lack of the characteristic 2175Å bump. For over 45 years, the source of the 2175Å extinction feature has yet to be positively identified. Small aromatic/PAH grains are suggested as a leading contender in dust grain models. The face-on spiral galaxy M101 is an ideal laboratory for the study of dust, with many well-studied HII regions and a steep metallicity and ionization gradient.The Interstellar Medium Absorption Gradient Experiment Rocket (IMAGER) probes the correlation between dust extinction, and the metallicity and radiation environment in M101 at ultraviolet wavelengths. IMAGER simultaneously images M101 in three 400Å-wide bandpasses, measuring the apparent strength of the 2175Å bump and the UV continuum.Combining data from IMAGER with high S/N far- and near- UV observations from the MAMA detectors on the Hubble STIS instrument, we examine the apparent strength of the 2175Å bump in HII regions of M101. With additional infrared data from Spitzer, the DIRTY radiative transfer model, and stellar evolution models, we probe the correlation between the 2175Å feature and the aromatic/PAH features across HII regions of varying metallicity and radiation field hardness. The results of this experiment will directly impact our understanding of the nature of dust and our ability to accurately account for the effects of dust on observations at all redshifts.

An enigmatic long-lasting gamma-ray burst not accompanied by a bright supernova.

PubMed

Della Valle, M; Chincarini, G; Panagia, N; Tagliaferri, G; Malesani, D; Testa, V; Fugazza, D; Campana, S; Covino, S; Mangano, V; Antonelli, L A; D'Avanzo, P; Hurley, K; Mirabel, I F; Pellizza, L J; Piranomonte, S; Stella, L

2006-12-21

Gamma-ray bursts (GRBs) are short, intense flashes of soft gamma-rays coming from the distant Universe. Long-duration GRBs (those lasting more than approximately 2 s) are believed to originate from the deaths of massive stars, mainly on the basis of a handful of solid associations between GRBs and supernovae. GRB 060614, one of the closest GRBs discovered, consisted of a 5-s hard spike followed by softer, brighter emission that lasted for approximately 100 s (refs 8, 9). Here we report deep optical observations of GRB 060614 showing no emerging supernova with absolute visual magnitude brighter than M(V) = -13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs. This demonstrates that some long-lasting GRBs can either be associated with a very faint supernova or produced by different phenomena.

The enigmatic object 2201 Oljato - Is it an asteroid or an evolved comet?

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy A.; Cochran, Anita L.; Barker, Edwin S.; Cruikshank, Dale P.; Hartmann, William K.

1993-01-01

The orbital properties of near-earth object 2201 have been associated with meteor showers, and its modeled orbital evolution is chaotic - a property which might indicate a history related to comets. Telescopic observations of its visible and near-infrared spectral reflectance, broad-band visible and near-infrared photometry, infrared radiometric measurements, and radar echoes are reported here from two apparitions, 1979 and 1983. This asteroid has a high radiometric albedo, a property not associated with comet nuclei. In certain wavelength regimes it is classified as an S-type asteroid, in others, an E-type, but its overall spectral reflectance is not typical of either taxonomic type, and neither type is thought of as cometlike. Unexpectedly high ultraviolet reflectance at the 1979 apparition was suggested to be the result of residual outgassing as in a comet. The UV photometric data are modeled as fluorescent emission from neutral species found in comets. The resulting calculations indicate a plausible value for OH and CN emission at 0.3085 and 0.38 micron relative to the observed range of active comets.

The Enigmatic Cornea and Intraocular Lens Calculations: The LXXIII Edward Jackson Memorial Lecture.

PubMed

Koch, Douglas D

2016-11-01

To review the progress and challenges in obtaining accurate corneal power measurements for intraocular lens (IOL) calculations. Personal perspective, review of literature, case presentations, and personal data. Through literature review findings, case presentations, and data from the author's center, the types of corneal measurement errors that can occur in IOL calculation are categorized and described, along with discussion of future options to improve accuracy. Advances in IOL calculation technology and formulas have greatly increased the accuracy of IOL calculations. Recent reports suggest that over 90% of normal eyes implanted with IOLs may achieve accuracy to within 0.5 diopter (D) of the refractive target. Though errors in estimation of corneal power can cause IOL calculation errors in eyes with normal corneas, greater difficulties in measuring corneal power are encountered in eyes with diseased, scarred, and postsurgical corneas. For these corneas, problematic issues are quantifying anterior corneal power and measuring posterior corneal power and astigmatism. Results in these eyes are improving, but 2 examples illustrate current limitations: (1) spherical accuracy within 0.5 D is achieved in only 70% of eyes with post-refractive surgery corneas, and (2) astigmatism accuracy within 0.5 D is achieved in only 80% of eyes implanted with toric IOLs. Corneal power measurements are a major source of error in IOL calculations. New corneal imaging technology and IOL calculation formulas have improved outcomes and hold the promise of ongoing progress. Copyright © 2016 Elsevier Inc. All rights reserved.

An Enigmatic Population of Luminous Globular Clusters in a Galaxy Lacking Dark Matter

NASA Astrophysics Data System (ADS)

van Dokkum, Pieter; Cohen, Yotam; Danieli, Shany; Kruijssen, J. M. Diederik; Romanowsky, Aaron J.; Merritt, Allison; Abraham, Roberto; Brodie, Jean; Conroy, Charlie; Lokhorst, Deborah; Mowla, Lamiya; O’Sullivan, Ewan; Zhang, Jielai

2018-04-01

We recently found an ultra diffuse galaxy (UDG) with a half-light radius of R e = 2.2 kpc and little or no dark matter. The total mass of NGC1052–DF2 was measured from the radial velocities of bright compact objects that are associated with the galaxy. Here, we analyze these objects using a combination of Hubble Space Telescope (HST) imaging and Keck spectroscopy. Their average size is < {r}h> =6.2+/- 0.5 pc and their average ellipticity is < ε > =0.18+/- 0.02. From a stacked Keck spectrum we derive an age of ≳9 Gyr and a metallicity of [Fe/H] = ‑1.35 ± 0.12. Their properties are similar to ω Centauri, the brightest and largest globular cluster in the Milky Way, and our results demonstrate that the luminosity function of metal-poor globular clusters is not universal. The fraction of the total stellar mass that is in the globular cluster system is similar to that in other UDGs, and consistent with “failed galaxy” scenarios, where star formation terminated shortly after the clusters were formed. However, the galaxy is a factor of ∼1000 removed from the relation between globular cluster mass and total galaxy mass that has been found for other galaxies, including other UDGs. We infer that a dark matter halo is not a prerequisite for the formation of metal-poor globular cluster-like objects in high-redshift galaxies.

An Enigmatic Case of Acute Mercury Poisoning: Clinical, Immunological Findings and Platelet Function.

PubMed

Kleffner, Ilka; Eichler, Susann; Ruck, Tobias; Schüngel, Lisa; Pfeuffer, Steffen; Polzer, Philipp; Dittrich, Ralf; Dziewas, Rainer; Gross, Catharina C; Göbel, Kerstin; Wiendl, Heinz; Kehrel, Beate E; Meuth, Sven G

2017-01-01

Severe mercury intoxication is very rare in developed countries, but still occurs as the result of volatile substance abuse, suicide attempts, occupational hazards, or endemic food ingestion as reported in the cases of public health disasters in Iraq and in Minamata Bay, Japan. Here, we describe the dramatic physical and cognitive decline of a 23-year-old patient caused by a severe methyl mercury (MeHg) intoxication of unknown origin. We show serial magnetic resonance imaging (MRI) of the patient's brain, as well as ex vivo analyses of blood and cerebrospinal fluid including multicolor flow cytometric measurements, functional assays of hemostaseologic efficacy, and evaluation of regulatory effector molecules. Together with the clinical history, our findings show the progressive neuronal degeneration accompanying the deterioration of the patient. Moreover, the ex vivo analyses display alterations of thrombocyte function and coagulation, as well as an immunological milieu facilitating autoimmunity. Despite the successful reduction of the MeHg concentration in the patient's blood with erythrocyte apheresis and chelator therapy, his condition did not improve and led to a persistent vegetative state. This case illustrates the neurotoxicity of MeHg following severe intoxication for the first time by serial MRI. Data on immune-cell and thrombocyte function as well as on coagulation in mercury poisoning reveal potential implications for anticoagulation and immunomodulatory treatment.

An Enigmatic Case of Acute Mercury Poisoning: Clinical, Immunological Findings and Platelet Function

PubMed Central

Kleffner, Ilka; Eichler, Susann; Ruck, Tobias; Schüngel, Lisa; Pfeuffer, Steffen; Polzer, Philipp; Dittrich, Ralf; Dziewas, Rainer; Gross, Catharina C.; Göbel, Kerstin; Wiendl, Heinz; Kehrel, Beate E.; Meuth, Sven G.

2017-01-01

Severe mercury intoxication is very rare in developed countries, but still occurs as the result of volatile substance abuse, suicide attempts, occupational hazards, or endemic food ingestion as reported in the cases of public health disasters in Iraq and in Minamata Bay, Japan. Here, we describe the dramatic physical and cognitive decline of a 23-year-old patient caused by a severe methyl mercury (MeHg) intoxication of unknown origin. We show serial magnetic resonance imaging (MRI) of the patient’s brain, as well as ex vivo analyses of blood and cerebrospinal fluid including multicolor flow cytometric measurements, functional assays of hemostaseologic efficacy, and evaluation of regulatory effector molecules. Together with the clinical history, our findings show the progressive neuronal degeneration accompanying the deterioration of the patient. Moreover, the ex vivo analyses display alterations of thrombocyte function and coagulation, as well as an immunological milieu facilitating autoimmunity. Despite the successful reduction of the MeHg concentration in the patient’s blood with erythrocyte apheresis and chelator therapy, his condition did not improve and led to a persistent vegetative state. This case illustrates the neurotoxicity of MeHg following severe intoxication for the first time by serial MRI. Data on immune-cell and thrombocyte function as well as on coagulation in mercury poisoning reveal potential implications for anticoagulation and immunomodulatory treatment. PMID:29033890

Enigmatic human tails: A review of their history, embryology, classification, and clinical manifestations.

PubMed

Tubbs, R Shane; Malefant, Jason; Loukas, Marios; Jerry Oakes, W; Oskouian, Rod J; Fries, Fabian N

2016-05-01

The presence of a human tail is a rare and intriguing phenomenon. While cases have been reported in the literature, confusion remains with respect to the proper classification, definition, and treatment methods. We review the literature concerning this anatomical derailment. We also consider the importance of excluding underlying congenital anomalies in these patients to prevent neurological deficits and other abnormal manifestations. © 2016 Wiley Periodicals, Inc.

The enigmatic truffle Fevansia aurantiaca is an ectomycorrhizal member of the Albatrellus lineage

Treesearch

Matthew E. Smith; Karlee J. Schell; Michael Castellano; Matthew J. Trappe; James M. Trappe

2013-01-01

Fevansia aurantiaca is an orange-colored truffle that has been collected infrequently in the Pacific Northwest of the USA. This sequestrate, hypogeous fungus was originally thought to be related to the genera Rhizopogon or Alpova in the Boletales, but the large, inflated cells in the trama and the very pale...

Arabinogalactan-proteins and the research challenges for these enigmatic plant cell surface proteoglycans

PubMed Central

Tan, Li; Showalter, Allan M.; Egelund, Jack; Hernandez-Sanchez, Arianna; Doblin, Monika S.; Bacic, Antony

2012-01-01

Arabinogalactan-proteins (AGPs) are complex glycoconjugates that are commonly found at the cell surface and in secretions of plants. Their location and diversity of structures have made them attractive targets as modulators of plant development but definitive proof of their direct role(s) in biological processes remains elusive. Here we overview the current state of knowledge on AGPs, identify key challenges impeding progress in the field and propose approaches using modern bioinformatic, (bio)chemical, cell biological, molecular and genetic techniques that could be applied to redress these gaps in our knowledge. PMID:22754559

A plate-driven model for enigmatic volcanic history of the Cascades-Yellowstone System

NASA Astrophysics Data System (ADS)

Szwaja, S.; Kincaid, C. R.; Druken, K. A.; MacDougall, J.

2013-12-01

The Cascades subduction system in the Pacific Northwest (USA) represents a complex tectonic setting, where rollback subduction of the Juan de Fuca plate beneath the North American plate, back-arc extension, and a possible mantle plume have been proposed to explain the complicated volcanic trends observed over the past 20 Ma. Plume and non-plume models have been developed to reconcile the voluminous Columbia River/Steens Flood Basalts (CSFB) (~20 Ma), the age progressive (15 Ma to present) Snake River Plain (SRP) that terminates at Yellowstone and the opposite, or westward trending High Lava Plains (HLP) volcanic track of eastern/central Oregon. We present results from laboratory experiments designed to test a plate-driven model for reproducing gross spatial-temporal characteristics of these three magmatic features. Models use a glucose fluid with temperature dependent viscosity in representing Earth's mantle and continuous rubber belts that kinematically reproduce subduction trends for the Cascades system. Experiments begin at 20 Ma with a volume of mantle residuum in the Cascades wedge that is elongated and restricted in the trench-parallel and trench-normal directions, respectively. The underlying assumption is that residuum was created in the wedge during an earlier plate steepening event that caused the flood basalts. Our models characterize dispersion patterns for the melt residuum material as it deforms within four-dimensional wedge circulation fields driven by rollback subduction (e.g. with a translational component of motion). Results show that residuum viscosity, relative to the ambient fluid, determines whether anomalous fluid can evolve to a morphology that matches the SRP/HLP tracks over ~15-20Ma. A weak residuum (e.g. retained partial melt) deforms over this time scale from the initial north-south oriented feature to an east-west trending morphology that is thin in both depth and north-south extent, material initially beneath CSFB is offset to the south, and is capable of producing opposite age progressions beneath the surface HLP/SRP track locations. The evolution of a high viscosity residuum in rollback-driven flow did not match the observed trends, as the feature deformed into an overly thick and wide morphology in the sub-HLP wedge compared to seismic data. Higher viscosity also produces stress coupling throughout the residuum, causing efficient entrainment from under the SRP towards the trench, leaving only ambient fluid beneath this track. In cases with stronger viscous coupling to the base of the overriding plate, the residuum is not able to deform into a morphology that is consistent with SRP/HLP tracks over the period 15 - 0 Ma. Models show only a limited range of conditions, where a low viscosity residuum is decoupled from the overriding plate, are capable of producing morphologies and offsets that roughly match observed spatial and temporal trends for primary features in the Pacific Northwest. Additional work is needed to understand the vertical heat/mass transfer processes that would enable deforming residuum to continually supply the bimodal magmatic output recorded over ~15Ma along the HLP and SRP tracks.

Similarities in features of autism and asthma and a possible link to acetaminophen use

PubMed Central

Becker, Kevin G.; Schultz, Stephen T.

2012-01-01

Autism and autism spectrum disorders are enigmatic conditions that have their origins in the interaction of genes and environmental factors. In this hypothesis, genes statistically associated with autism are emphasized to be important in inflammation and in innate immune pathways, including pathways for susceptibility to asthma. The role of acetaminophen (paracetamol) in an increased risk for asthma is described and a possible similar link to an increased risk for autism is suggested. PMID:19748189

Conductivity Dynamics of the Metal to Insulator Transition in EuNiO3/LANiO3 Superlattices

DTIC Science & Technology

2016-02-07

lead to emergent phenomena with the insulator -to- insulator transition (IMT) being one of the most enigmatic from fundamental and applied perspectives...2015 Approved for Public Release; Distribution Unlimited Final Report: Conductivity Dynamics of the Metal to Insulator Transition in EuNiO3/LANiO3...Conductivity Dynamics of the Metal to Insulator Transition in EuNiO3/LANiO3 Superlattices Report Title In numerous transition metal oxides (TMO

Archeological and Historical Studies in the White Castle Gap Revetment, Iberville Parish, Louisiana.

DTIC Science & Technology

1982-01-01

enigmatic nature of the Poverty Point type site, coupled with its temporal parallels in coastal Mexico , lead Weaver (1972: 281) to suggest that the horizon...trade between Mexico and the Mississippi drainage, it must be noted that we have neither evidence of site-unit intrusions of Mexican peoples, nor...Two canoes have examined the coast thirty leagues towards Mexico , and twenty-five towards Florida (deTonty 1905: 35,36). The column to which de Tonty

Synthesis of GEMS from Shock-accelerated Crystalline Dust in Superbubbles: Model and Predictions

NASA Technical Reports Server (NTRS)

Westphal, Andrew J.; Bradley, John P.

2005-01-01

GEMS (Glass Embedded with Metals and Sulfides) are highly enigmatic yet common components of anhydrous IDPs. We have recently proposed a model of GEMS formation from shock-accelerated crystalline dust in superbubbles[1] which explains the three most perplexing properties of GEMS: pseudomorphism[2], their chemistry[3], and their size range. In this Abstract, we briefly review the main points of the model, and suggest tests that will either prove or rule out this hypothesis.

Category III chronic prostatitis/chronic pelvic pain syndrome: insights from the National Institutes of Health Chronic Prostatitis Collaborative Research Network studies.

PubMed

Nickel, J Curtis; Alexander, Richard B; Anderson, Rodney; Berger, Richard; Comiter, Craig V; Datta, Nand S; Fowler, Jackson E; Krieger, John N; Landis, J Richard; Litwin, Mark S; McNaughton-Collins, Mary; O'Leary, Michael P; Pontari, Michel A; Schaeffer, Anthony J; Shoskes, Daniel A; White, Paige; Kusek, John; Nyberg, Leroy

2008-07-01

Chronic prostatitis/chronic pelvic pain syndrome remains an enigmatic medical condition. Creation of the National Institutes of Health-funded Chronic Prostatitis Collaborative Research Network (CPCRN) has stimulated a renewed interest in research on and clinical aspects of chronic prostatitis/chronic pelvic pain syndrome. Landmark publications of the CPCRN document a decade of progress. Insights from these CPCRN studies have improved our management of chronic prostatitis/chronic pelvic pain syndrome and offer hope for continued progress.

Volatiles in the Desert: Subtle Remote-sensing Signatures of the Dakhleh Oasis Catastrophic Event, Western Desert, Egypt

NASA Technical Reports Server (NTRS)

Haldemann, A. F. C.; Kleindienst, M. R.; Churcher, C. S.; Smith, J. R.; Schwarcz, H. P.; Osinski, G.

2005-01-01

Over the past decade members of the Dakhleh Oasis Project have studied enigmatic signatures in the Pleistocene geologic record of portions of the Dakhleh oasis and palaeo-oasis in Egypt's Western Desert [1,2]. In particular, Si-Ca-Al rich glass melt (Dakhleh Glass, Fig. 1) points to a catastrophic event between c.100,000-200,000 years ago [3] in this well-studied African savannah and freshwater lake Middle Stone Age environment [4,5].

Analysis of heavy metal accumulation in fish from the coastal waters of Terengganu, Malaysia

NASA Astrophysics Data System (ADS)

Rosli, M. N. R.; Samat, S. B.; Yasir, M. S.

2018-04-01

Bioaccumulation of toxic metals in fish causes serious threats to the human when they are consumed. Thus, the detection of toxic element concentration levels in fish is important. The accumulation of four heavy metal concentration of Cd, Cu, Mn and Zn in fish was determined. Five fish species namely Epinephelus lanceolatus, Rastrelliger, Megalaspis cordyla, Bramidae and Siganus canaliculatus were collected from the coastal waters of Terengganu, Malaysia. The analysis was done using inductive coupled plasma-mass spectrometer (ICP-MS) technique. The accumulation of the four heavy metals in muscle tissues of the fish are lower compared to liver and gill tissues. Cd concentration was higher in liver tissues except in Megalaspis cordyla. Meanwhile Cu concentration was higher in liver for all selected fishes. Mn concentration was higher in gill tissues of all fish studied while Zn concentration was higher in gill tissues except in Epinephelus lanceolatus and Rastrelliger. The highest average level of heavy metal recorded in fish is Zn (11.05 × 10-2 ± 1.44 × 10-2 mg kg-1) followed by Mn (1.81 × 10-2 ± 0.58 × 10-2 mg kg-1), Cu (0.70 × 10-2 ± 0.10 × 10-2 mg kg-1) and Cd (0.52×10-2 ± 0.27 × 10-2 mg kg-1). The metal concentration found in this study was lower than the national and international Recommended Dietary Allowance (RDA) for human consumption. Long term monitoring system of metal bioaccumulation in fishes need to be done to provide useful information for the assessment of the potential health risks of metals in Malaysia.

Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

PubMed

Ravago-Gotanco, Rachel; de la Cruz, Talna Lorena; Pante, Ma Josefa; Borsa, Philippe

2018-01-01

The taxonomy of the mottled rabbitfish Siganus fuscescens species complex has long been challenging. In this study, we analyzed microsatellite genotypes, mitochondrial lineages, and morphometric data from 373 S. fuscescens individuals sampled from the northern Philippines and Hong Kong (South China Sea, Philippine Sea and Sulu Sea basins), to examine putative species boundaries in samples comprising three co-occurring mitochondrial lineages previously reported to characterize S. fuscescens (Clade A and Clade B) or S. canaliculatus (Clade C). We report the existence of two cryptic species within S. fuscescens in the northeast region of the South China Sea and northern Philippine Sea, supported by genetic and morphological differences. Individual-based assignment methods recovered concordant groupings of individuals into two nuclear genotype clusters (Cluster 1, Cluster 2) with (1) limited gene flow, if any, between them (FST = 0.241; P < 0.001); (2) low frequency of later-generation hybrids; (3) significant association with mitochondrial Clade A and Clade B, respectively; and (4) subtle yet significant body shape differences as inferred from geometric morphometric analysis. The divergence between mitochondrial Clade C and the two other clades was not matched by genetic differences at microsatellite marker loci. The occurrence of discordant mitonuclear combinations (20.5% of the total number of individuals) is thought to result from mitochondrial introgression, consistent with a scenario of demographic, and presumably spatial, post-Pleistocene expansion of populations from northern regions into a secondary contact zone in the South China Sea. Mitonuclear discordance due to introgression obscures phylogenetic relationships for recently-diverged lineages, and cautions against the use of mitochondrial markers alone for species identification within the mottled rabbitfish species complex in the South China Sea region.

Defining the scope of systems of care: an ecological perspective.

PubMed

Cook, James R; Kilmer, Ryan P

2010-02-01

The definition of a system of care (SOC) can guide those intending to develop and sustain SOCs. Hodges, Ferreira, Israel, and Mazza [Hodges, S., Ferreira, K., Israel, N., & Mazza, J. (in press). Systems of care, featherless bipeds, and the measure of all things. Evaluation and Program Planning] have emphasized contexts in which services are provided to families, plus the adaptive, dynamic, complex nature of systems and multiple components that comprise SOCs. However, two areas need additional clarification: (1) the nature of the "system" of concern in a "system of care," and how it should differ from a "service delivery system"; and (2) the degree to which intended, or desired, outcomes of a SOC extend beyond increased access to "necessary" services and supports. These prime issues in the conceptualization of SOCs are addressed, drawing on ecological theory to underscore the need for broader systems--including factors in the proximal and distal contexts of children and families--to be engaged in the process of promoting well-being and helping children and families function and participate fully in their communities. A revised definition is proposed, with implications for the implementation of SOCs.

Bipedal animals, and their differences from humans.

PubMed

Alexander, R McN

2004-05-01

Humans, birds and (occasionally) apes walk bipedally. Humans, birds, many lizards and (at their highest speeds) cockroaches run bipedally. Kangaroos, some rodents and many birds hop bipedally, and jerboas and crows use a skipping gait. This paper deals only with walking and running bipeds. Chimpanzees walk with their knees bent and their backs sloping forward. Most birds walk and run with their backs and femurs sloping at small angles to the horizontal, and with their knees bent. These differences from humans make meaningful comparisons of stride length, duty factor, etc., difficult, even with the aid of dimensionless parameters that would take account of size differences, if dynamic similarity were preserved. Lizards and cockroaches use wide trackways. Humans exert a two-peaked pattern of force on the ground when walking, and an essentially single-peaked pattern when running. The patterns of force exerted by apes and birds are never as markedly two-peaked as in fast human walking. Comparisons with quadrupedal mammals of the same body mass show that human walking is relatively economical of metabolic energy, and human running is expensive. Bipedal locomotion is remarkably economical for wading birds, and expensive for geese and penguins.

Effect of reduced gravity on the preferred walk-run transition speed

NASA Technical Reports Server (NTRS)

Kram, R.; Domingo, A.; Ferris, D. P.

1997-01-01

We investigated the effect of reduced gravity on the human walk-run gait transition speed and interpreted the results using an inverted-pendulum mechanical model. We simulated reduced gravity using an apparatus that applied a nearly constant upward force at the center of mass, and the subjects walked and ran on a motorized treadmill. In the inverted pendulum model for walking, gravity provides the centripetal force needed to keep the pendulum in contact with the ground. The ratio of the centripetal and gravitational forces (mv2/L)/(mg) reduces to the dimensionless Froude number (v2/gL). Applying this model to a walking human, m is body mass, v is forward velocity, L is leg length and g is gravity. In normal gravity, humans and other bipeds with different leg lengths all choose to switch from a walk to a run at different absolute speeds but at approximately the same Froude number (0.5). We found that, at lower levels of gravity, the walk-run transition occurred at progressively slower absolute speeds but at approximately the same Froude number. This supports the hypothesis that the walk-run transition is triggered by the dynamics of an inverted-pendulum system.

Bipedal animals, and their differences from humans

PubMed Central

Alexander, R McN

2004-01-01

Humans, birds and (occasionally) apes walk bipedally. Humans, birds, many lizards and (at their highest speeds) cockroaches run bipedally. Kangaroos, some rodents and many birds hop bipedally, and jerboas and crows use a skipping gait. This paper deals only with walking and running bipeds. Chimpanzees walk with their knees bent and their backs sloping forward. Most birds walk and run with their backs and femurs sloping at small angles to the horizontal, and with their knees bent. These differences from humans make meaningful comparisons of stride length, duty factor, etc., difficult, even with the aid of dimensionless parameters that would take account of size differences, if dynamic similarity were preserved. Lizards and cockroaches use wide trackways. Humans exert a two-peaked pattern of force on the ground when walking, and an essentially single-peaked pattern when running. The patterns of force exerted by apes and birds are never as markedly two-peaked as in fast human walking. Comparisons with quadrupedal mammals of the same body mass show that human walking is relatively economical of metabolic energy, and human running is expensive. Bipedal locomotion is remarkably economical for wading birds, and expensive for geese and penguins. PMID:15198697

Mechanical analysis of infant carrying in hominoids

PubMed Central

2007-01-01

In all higher nonhuman primates, species survival depends upon safe carrying of infants clinging to body hair of adults. In this work, measurements of mechanical properties of ape hair (gibbon, orangutan, and gorilla) are presented, focusing on constraints for safe infant carrying. Results of hair tensile properties are shown to be species-dependent. Analysis of the mechanics of the mounting position, typical of heavier infant carrying among African apes, shows that both clinging and friction are necessary to carry heavy infants. As a consequence, a required relationship between infant weight, hair–hair friction coefficient, and body angle exists. The hair–hair friction coefficient is measured using natural ape skin samples, and dependence on load and humidity is analyzed. Numerical evaluation of the equilibrium constraint is in agreement with the knuckle-walking quadruped position of African apes. Bipedality is clearly incompatible with the usual clinging and mounting pattern of infant carrying, requiring a revision of models of hominization in relation to the divergence between apes and hominins. These results suggest that safe carrying of heavy infants justify the emergence of biped form of locomotion. Ways to test this possibility are foreseen here. PMID:18030438

The Double-Edged Sword: Conserved Functions of Extracellular Hsp90 in Wound Healing and Cancer

PubMed Central

Hance, Michael W.; Nolan, Krystal D.; Isaacs, Jennifer S.

2014-01-01

Heat shock proteins (Hsps) represent a diverse group of chaperones that play a vital role in the protection of cells against numerous environmental stresses. Although our understanding of chaperone biology has deepened over the last decade, the “atypical” extracellular functions of Hsps have remained somewhat enigmatic and comparatively understudied. The heat shock protein 90 (Hsp90) chaperone is a prototypic model for an Hsp family member exhibiting a duality of intracellular and extracellular functions. Intracellular Hsp90 is best known as a master regulator of protein folding. Cancers are particularly adept at exploiting this function of Hsp90, providing the impetus for the robust clinical development of small molecule Hsp90 inhibitors. However, in addition to its maintenance of protein homeostasis, Hsp90 has also been identified as an extracellular protein. Although early reports ascribed immunoregulatory functions to extracellular Hsp90 (eHsp90), recent studies have illuminated expanded functions for eHsp90 in wound healing and cancer. While the intended physiological role of eHsp90 remains enigmatic, its evolutionarily conserved functions in wound healing are easily co-opted during malignancy, a pathology sharing many properties of wounded tissue. This review will highlight the emerging functions of eHsp90 and shed light on its seemingly dichotomous roles as a benevolent facilitator of wound healing and as a sinister effector of tumor progression. PMID:24805867

Fungal Melanins Differ in Planar Stacking Distances

PubMed Central

Casadevall, Arturo; Nakouzi, Antonio; Crippa, Pier R.; Eisner, Melvin

2012-01-01

Melanins are notoriously difficult to study because they are amorphous, insoluble and often associated with other biological materials. Consequently, there is a dearth of structural techniques to study this enigmatic pigment. Current models of melanin structure envision the stacking of planar structures. X ray diffraction has historically been used to deduce stacking parameters. In this study we used X ray diffraction to analyze melanins derived from Cryptococcus neoformans, Aspergillus niger, Wangiella dermatitides and Coprinus comatus. Analysis of melanin in melanized C. neoformans encapsulated cells was precluded by the fortuitous finding that the capsular polysaccharide had a diffraction spectrum that was similar to that of isolated melanin. The capsular polysaccharide spectrum was dominated by a broad non-Bragg feature consistent with origin from a repeating structural motif that may arise from inter-molecular interactions and/or possibly gel organization. Hence, we isolated melanin from each fungal species and compared diffraction parameters. The results show that the inferred stacking distances of fungal melanins differ from that reported for synthetic melanin and neuromelanin, occupying intermediate position between these other melanins. These results suggest that all melanins have a fundamental diffracting unit composed of planar graphitic assemblies that can differ in stacking distance. The stacking peak appears to be a distinguishing universal feature of melanins that may be of use in characterizing these enigmatic pigments. PMID:22359541

Cd(II)-coordination polymers based on tetracarboxylic acid and diverse bis(imidazole) ligands: Synthesis, structural diversity and photoluminescence properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arıcı, Mürsel, E-mail: marici@ogu.edu.tr; Yeşilel, Okan Zafer; Taş, Murat

Three new Cd(II)-coordination polymers, namely, ([Cd{sub 2}(μ{sub 6}-ao{sub 2}btc)(μ-1,5-bipe){sub 2}]·2H{sub 2}O){sub n} (1), ([Cd{sub 2}(μ{sub 6}-ao{sub 2}btc)(μ-1,4-bix){sub 2}]{sub n}·2DMF) (2) and ([Cd{sub 2}(μ{sub 8}-abtc)(μ-1,4-betix)]·DMF·H{sub 2}O){sub n} (3) (ao{sub 2}btc=di-oxygenated form of 3,3′,5,5′-azobenzenetetracarboxylate, 1,5-bipe: 1,5-bis(imidazol-1yl)pentane, 1,4-bix=1,4-bis(imidazol-1ylmethyl)benzene, 1,4-betix=1,4-bis(2-ethylimidazol-1ylmethyl)benzene) were synthesized with 3,3′,5,5′-azobenzenetetracarboxylic acid and flexible, semi-flexible and semi-flexible substituted bis(imidazole) linkers. They were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and thermal analyses (TG/DTA). Complexes 1–3 exhibited structural diversities depending on flexible, semi-flexible and semi-flexible substituted bis(imidazole) ligands. Complex 1 was 2D structure with 3,6L18 topology. Complex 2 had a 3D pillar-layered framework with the raremore » sqc27 topology. When semi-flexible substituted bis(imidazole) linker was used, 3D framework of complex 3 was obtained with the paddlewheel Cd{sub 2}(CO{sub 2}){sub 4}-type binuclear SBU. Moreover, thermal and photoluminescence properties of the complexes were determined in detailed. - Graphical abstract: In this study, three novel Cd(II)-coordination polymers were synthesized with 3,3′,5,5′-azobenzenetetracarboxylic acid and flexible, semi-flexible and semi-flexible substituted bis(imidazole) linkers. They were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and thermal analyses (TG/DTA). Complexes 1–3 exhibited structural diversities depending on flexible, semi-flexible and semi-flexible substituted bis(imidazole) ligands. Complex 1 was 2D structure with 3,6L18 topology. Complex 2 had a 3D pillar-layered framework with the rare sqc27 topology

The influence of oceans on Martian volcanism

NASA Technical Reports Server (NTRS)

Mouginis-Mark, Peter

1993-01-01

Geomorphological evidence for episodic oceans on Mars has recently been identified. This idea of large bodies of water on Mars is innovative and controversial compared to the more generally accepted view of a 'dry Mars', but also enables some of the more enigmatic volcanic landforms to be reinterpreted in a self-consistent model. This hypothesis can be used to develop new models for the mode of formation of several volcanic landforms in the W. Tharsis and S.E. Elysium Planitia regions of Mars.

Category III Chronic Prostatitis/Chronic Pelvic Pain Syndrome: Insights from The National Institutes of Health Chronic Prostatitis Collaborative Research Network Studies

PubMed Central

Nickel, J. Curtis; Alexander, Richard B.; Anderson, Rodney; Berger, Richard; Comiter, Craig V.; Datta, Nand S.; Fowler, Jackson E.; Krieger, John N.; Landis, J. Richard; Litwin, Mark S.; McNaughton-Collins, Mary; O'Leary, Michael P.; Pontari, Michel A.; Schaeffer, Anthony J.; Shoskes, Daniel A.; White, Paige; Kusek, John; Nyberg, Leroy

2010-01-01

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) remains an enigmatic medical condition. Creation of the (NIH) Chronic Prostatitis Collaborative Research Network (CPCRN) funded by the National Institutes of Health has stimulated a renewed interest in the research and clinical aspects of CP/CPPS. Landmark publications of the NIH-CPCRN over the last 10 years document a decade of progress. Insights from these CPCRN studies have improved our management of patients diagnosed with CP/CPPS and offer hope for continued progress. PMID:18765132

Enigmatic origin of hepatitis B virus: An ancient travelling companion or a recent encounter?

PubMed Central

Zehender, Gianguglielmo; Ebranati, Erika; Gabanelli, Elena; Sorrentino, Chiara; Lo Presti, Alessandra; Tanzi, Elisabetta; Ciccozzi, Massimo; Galli, Massimo

2014-01-01

Hepatitis B virus (HBV) is the leading cause of liver disease and infects an estimated 240 million people worldwide. It is characterised by a high degree of genetic heterogeneity because of the use of a reverse transcriptase during viral replication. The ten genotypes (A-J) that have been described so far further segregate into a number of subgenotypes which have distinct ethno-geographic distribution. Genotypes A and D are ubiquitous and the most prevalent genotypes in Europe (mainly represented by subgenotypes D1-3 and A2); genotypes B and C are restricted to eastern Asia and Oceania; genotype E to central and western Africa; and genotypes H and F (classified into 4 subgenotypes) to Latin America and Alaska. This review summarises the data obtained by studying the global phylodynamics and phylogeography of HBV genotypes, particularly those concerning the origin and dispersion histories of genotypes A, D, E and F and their subgenotypes. The lack of any consensus concerning the HBV substitution rate and the conflicting data obtained using different calibration approaches make the time of origin and divergence of the various genotypes and subgenotypes largely uncertain. It is hypothesised that HBV evolutionary rates are time dependent, and that the changes depend on the main transmission routes of the genotypes and the dynamics of the infected populations. PMID:24976700

Photometry, polarimetry, spectroscopy, and spectropolarimetry of the enigmatic Wolf-Rayet star EZ Canis Majoris

NASA Technical Reports Server (NTRS)

Robert, Carmelle; Moffat, Anthony F. J.; Drissen, Laurent; Lamontagne, Robert; Seggewiss, Wilhelm; Niemela, Virpi S.; Cerruti, Miguel A.; Barrett, Paul; Bailey, Jeremy; Garcia, Jorge

1992-01-01

New observations of the peculiar Wolf-Rayet star EZ Canis Majoris collected since 1987 are presented, and photometric, polarimetric, spectroscopic, and spectropolarimetric data are discussed. Linear polarization data are well fitted with an eccentric binary model where an additional free parameter is included to allow for epoch-dependent changes of the geometrical electron distribution in the W-R envelope. This yields a set of basic parameters, including an eccentricity e = 0.39 +/- 0.02 and an orbital inclination i = 114 deg +/- 3 deg. The spectroscopic data show global profile variations for all three observed strong emission lines He II 5412 A, C IV 5807 A, and He I 5876 A. Radial velocities of the lines vary with the 3.766-day period. Radially expanding inhomogeneities are superposed on the line profiles and variable polarization in the lines is observed.

Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier

NASA Technical Reports Server (NTRS)

Mcintyre, Andrew

1992-01-01

Equatorial Atlantic surface waters respond directly to changes in zonal and meridional lower tropospheric winds forced by annual insolation. This mechanism has its maximum effect along the equatorial wave guide centered on 10 deg W. The result is to amplify even subtle tropical climate changes such that they are recorded by marked amplitude changes in the proxy signals. Model realizations, NCAR AGCM and OGCM for 0 Ka and 126 Ka (January and July), and paleoceanographic proxy data show that these winds are also forced by insolation changes at the orbital periods of precession and obliquity. Perhelion in boreal summer produces a strengthened monsoon, e.g., increase meridional and decrease zonal wind stress. This reduces oceanic Ekman divergence and thermocline/nutricline shallowing. The result, in the equatorial Atlantic, is reduced primary productivity and higher euphotic zone temperatures; vice versa for perihelion in boreal winter. Perihelion is controlled by precession. Thus, the dominant period in spectra from a stacked SST record (0-252 Ka BP) at the site of the equatorial Atlantic amplifier is 23 Ky (53 percent of the total variance). This precessional period is coherent (k = 0.920) and in phase with boreal summer insolation. Oscillations of shorter period are present in records from cores sited beneath the amplifier region. These occur between 12.5 and 74.5 Ka BP, when eccentricity modulation of precession is at a minimum. Within this time interval there are 21 cycles with mean periods of 3.0 plus or minus 0.5 Ky. Similar periods have been documented from high latitude regions, e.g., Greenland ice cores from Camp Century. The Camp Century signal in this same time interval contains 21 cycles. A subjective correlation was made between the Camp Century and the equatorial records; the signals were statistically similar, r = 0.722 and k = 0.960.

The enigmatic WR46: A binary or a pulsator in disguise. II. The spectroscopy

NASA Astrophysics Data System (ADS)

Veen, P. M.; van Genderen, A. M.; Crowther, P. A.; van der Hucht, K. A.

2002-04-01

We present spectroscopic monitoring of the Wolf-Rayet (WR) star WR 46 between 1989 and 1998, which has been obtained simultaneously with multicolour photometry (Veen et al. \\cite{Veen02a}, Paper I). The spectroscopic monitoring data show that the radiative fluxes of the optical emission lines (O Vi 3811/34, O Vi 5290, N V 4944, N V 4604/20, He Ii 4686, He Ii 4859, He Ii 5411, He Ii 6560) vary in concert with the photometric single-wave (sw) frequency f_sw (Paper I), and also the difference of that period between 1989 and 1991. The line-flux variability does not provide obvious support for a short second period (Paper I). The radial-velocity variations show a remarkable behaviour: usually, they display a coherent single-wave on the time scale of the double-wave period, while during some nights the radial velocity appears surprisingly to stay constant (see also Marchenko et al. \\cite{Marchenko00}). These so-called stand-stills may be related to the observed time-delay effects. A time-delay effect manifests itself in several phenomena. Firstly, the line flux shows small, but persistent, time-delays for lines originating from lower optical depths, the outer-wind lines (N V 4604/20 and He Ii). Secondly, the radial-velocity variations display much larger time-delays than the line fluxes and their behaviour appears less consistent. Assuming that the double-wave period controls the radial velocity, the stand-still is observed to start when the radial motion is in anti-phase with the presumed orbital motion. Thirdly, the outer-wind lines are observed to enter a stand-still much later than the inner-wind lines. Fourthly, the radial-velocity variations of the peaks of the emission lines precede the radial-velocity variations of the wings of those lines. In addition to line-flux- and radial-velocity variability, the He Ii 4686 emission line shows pronounced line-profile changes on a time scale of hours. Our monitoring is not sufficient to study this in detail. Furthermore, we discern a flaring behaviour, i.e., an emission bump appeared on the blue wing of two He Ii-lines (around -1700 km s-1) lasting less than 5 min. Finally, the line fluxes follow the observed brightenings, also on a time scale of years. We conclude that the short-term cyclic variability confirms the WR nature as established from the WR standard model analysis by Crowther et al. (\\cite{Crowther95}; hereafter referred to as CSH). The various time-delay effects are consistent with the formation of the spectrum in a stratified stellar wind. The outer layers trail the inner ones. The variability is inconsistent with the formation of the spectrum in a stellar disc as proposed by Niemela et al. (\\cite{Niemela95}) and Steiner & Diaz (\\cite{Steiner98}). The long-term cyclic variability of the brightness and line fluxes is related to an increase of the mass-loss-rate, and, possibly, to the period changes. The interpretation of the nature of the variability is deferred to Veen et al. (\\cite{Veen02b}, Paper III). Based on observations collected at the European Southern Observatory (ESO), La Silla, Chile.

A polymicrobial perspective of pulmonary infections exposes an enigmatic pathogen in cystic fibrosis patients.

PubMed

Sibley, Christopher D; Parkins, Michael D; Rabin, Harvey R; Duan, Kangmin; Norgaard, Jens C; Surette, Michael G

2008-09-30

Lung disease is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients. A modest number of bacterial pathogens have been correlated with pulmonary function decline; however, microbiological and molecular evidence suggests that CF airway infection is polymicrobial. To obtain a more complete assessment of the microbial community composition and dynamics, we undertook a longitudinal study by using culture-independent and microbiological approaches. In the process, we demonstrated that within complex and dynamic communities, the Streptococcus milleri group (SMG) can establish chronic pulmonary infections and at the onset of 39% of acute pulmonary exacerbations, SMG is the numerically dominant pathogen. We report the comprehensive polymicrobial community dynamics of a CF lung infection in a clinically relevant context. If a given organism, such as Pseudomonas aeruginosa, becomes resistant to antibiotic therapy, an alternative treatment avenue may mediate the desired clinical response by effectively managing the composition of the microbial community.

An enigmatic Hawaiian moth is a missing link in the adaptive radiation of Schiedea.

PubMed

Weller, Stephen G; Sakai, Ann K; Campbell, Diane R; Powers, John M; Peña, Sean R; Keir, Matthew J; Loomis, Alexander K; Heintzman, Scott M; Weisenberger, Lauren

2017-02-01

Shifts in pollination may drive adaptive diversification of reproductive systems within plant lineages. The monophyletic genus Schiedea is a Hawaiian lineage of 32 extant species, with spectacular diversity in reproductive systems. Biotic pollination is the presumed ancestral condition, but this key element of the life history and its role in shaping reproductive systems has remained undocumented. We observed floral visitors to two species of Schiedea and conducted field experiments to test pollinator effectiveness. We used choice tests to compare attraction of pollinators to species hypothesized to be biotically vs wind-pollinated. Pseudoschrankia brevipalpis (Erebidae), a recently described moth species known only from O'ahu, visited hermaphroditic Schiedea kaalae and S. hookeri and removed nectar from their unique tubular nectary extensions. Pseudoschrankia brevipalpis effectively pollinates S. kaalae; single visits to emasculated flowers resulted in pollen transfer. In choice tests, P. brevipalpis strongly preferred these hermaphroditic species over two subdioecious species capable of wind pollination. A shift from biotic to abiotic pollination is clearly implicated in the diversification of reproductive systems within Schiedea. Abundant pollination by a previously unknown native moth in experimental and restored populations suggests the potential for restoration to re-establish native plant-pollinator interactions critical for production of outcrossed individuals with high fitness. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Enigmatic rift-parallel, strike-slip faults around Eyjafjörður, Northern Iceland

NASA Astrophysics Data System (ADS)

Proett, J. A.; Karson, J. A.

2014-12-01

Strike-slip faults along mid-ocean ridge spreading centers are generally thought to be restricted to transform boundaries connecting rift segments. Faults that are parallel to spreading centers are generally assumed to be normal faults associated with tectonic extension. However, clear evidence of north-south (rift-parallel), strike-slip displacements occur widely around the southern portion of Eyjafjörður, northern Iceland about 50 km west of the Northern Rift Zone. The area is south of the southernmost strand (Dalvík Lineament) of the NW-SE-trending, dextral-slip, Tjӧrnes Fracture Zone (where N-S, sinistral, strike-slip "bookshelf" faulting occurs). Faults in the Eyjafjörður area cut 8.5-10 m.y. basaltic crust and are parallel to spreading-related dikes and are commonly concentrated along dike margins. Fault rocks range from fault breccia to gouge. Riedel shears and other kinematic indicators provide unambiguous evidence of shear sense. Most faults show evidence of sinistral, strike-slip movement but smaller proportions of normal and oblique-slip faults also are present. Cross cutting relations among the different types of faults are inconsistent and appear to be related to a single deformation event. Fault slip-line kinematic analysis yields solutions indicating sinistral-normal oblique-slip overall. These results may be interpreted in terms of either previously unrecognized transform-fault bookshelf faulting or slip accommodating block rotation associated with northward propagation of the Northern Rift Zone.

The Enigmatic and Ephemeral M Dwarf System KOI 6705: Cheshire Cat or Wild Goose?

NASA Astrophysics Data System (ADS)

Gaidos, Eric; Mann, Andrew W.; Ansdell, Megan

2016-01-01

We confirm a 0.995 day periodic planetary transit-like signal, KOI 6705.01, in the Kepler light curve of the star KIC 6423922. Optical and infrared spectra show that this star is a mid M-type dwarf with an effective temperature =\\3327+/- 60 K, metallicity [Fe/H] = -0.08 ± 0.10, radius =\\0.31+/- 0.03R⊙, and mass = 0.28 ± 0.05M⊙. The star is ≈ 70 pc away and its space motion, rotation period, and lack of Hα emission indicate it is an older member of the “thin disk” population. On the other hand, the star exhibits excess infrared emission suggesting a dust disk more typical of a very young star. If the KOI 6705.01 signal is produced by a planet, the transit depth of 60 ppm means its radius is only {0.26}-0.029+0.034R⊕, or about the size of the Moon. However, the duration (≳ 3 hr) and time variation of KOI 6705.01 are anomalous: the signal was undetected in the first two years of the mission and increased through the latter two years. These characteristics require implausible orbits and material properties for any planet and rule out such an explanation, although a dust cloud is possible. We excluded several false positive scenarios including background stars, scattered light from stars that are nearby on the sky, and electronic cross-talk between detector readout channels. We find the most likely explanation to be that KOI 6705.01 is a false positive created by charge transfer inefficiency in a detector column on which KIC 6423922 and a 1.99 day eclipsing binary both happened to fall.

Low basal salivary flow and burning mouth syndrome: new evidence in this enigmatic pathology.

PubMed

Spadari, Francesco; Venesia, Paolo; Azzi, Lorenzo; Veronesi, Giovanni; Costantino, Dario; Croveri, Fabio; Farronato, Davide; Tagliabue, Angelo; Tettamanti, Lucia

2015-03-01

Burning mouth syndrome remains a puzzling condition. One symptom commonly associated with the burning sensation is xerostomia. The current study measured basal and stimulated salivary flow in a group of burning mouth syndrome patients. Three groups of patients were recruited: 44 burning mouth syndrome patients, 27 oral lichen planus patients and 40 healthy patients. We chose to measure basal salivary flow and stimulated salivary flow in the three groups of patients using the 'spitting' method. Thus, the patients were asked to spit every minute for 5 min. Afterwards, they were asked to repeat the procedure a second time, but a drop of citric acid was positioned on their tongue every minute to stimulate salivary secretion. After 14 days, the same procedure was repeated for 15 min. Although there was no significant difference between the burning mouth syndrome group and the other two groups regarding the stimulated volumes, an important difference was found in the basal volumes, with the burning mouth syndrome patients showing lower values. The outcomes of our research demonstrate the presence of very low basal salivary flow in burning mouth syndrome patients compared with the other two groups, but the stimulated salivary flow was equal, if not higher, in the burning mouth syndrome patients. This study contributes new topics for further investigation of a solution to the very mysterious pathology represented by burning mouth syndrome. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

XTE J1946+274 = GRO J1944+26: An Enigmatic Be/X-ray Binary

NASA Technical Reports Server (NTRS)

Wilson, Colleen A.; Finger, Mark H.; Coe, M. J.; Negueruela, Ignacio; Six, N. Frank (Technical Monitor)

2002-01-01

XTE J1946+274 = GRO J1944+26 is a 15.8-s Be/X-ray pulsar discovered simultaneously in 1998 September with the, Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) and the All-Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE). Pulse timing analysis yielded an orbital period of 169.2 days, a moderate eccentricity of 0.33, and implied a mass function of 9.7 solar mass. We observed evidence for an accretion disk, a correlation between measured spin-up rate and flux, which was fitted to obtain a distance estimate of 9.2 +/- 1.0 kpc. XTE J1946+274 remained active from 1998 September - 2001 July, undergoing 13 outbursts that were not locked in orbital phase. Comparing RXTE PCA observations from the initial bright outburst in 1998 and the last pair of outburst in 2001, we found energy and intensity dependent pulse profile variations in both outbursts and hardening spectra with increasing intensity during the fainter 2001 outbursts. In 2001 July, optical H(alpha) observations indicate a density perturbation appeared in the Be disk as the X-ray outbursts ceased. We propose that the equatorial plane of the Be star is inclined with respect to the orbital plane in this system and that this inclination may produce the unusual outburst behavior of the system.

XTE J1946+274 = GRO J1944+26: An Enigmatic Be/X-Ray Binary

NASA Technical Reports Server (NTRS)

Wilson, Colleen A.; Finger, Mark H.; Coe, M. J.; Negueruela, Ignacio

2003-01-01

XTE J1946+274 = GRO J1944+26 is a 15.8 s Be/X-ray pulsar discovered simultaneously in 1998 September with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) and the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE). Here we present new results from BATSE and RXTE including a pulse timing analysis, spectral analysis, and evidence for an accretion disk. Our pulse timing analysis yielded an orbital period of 169.2 days, a moderate eccentricity 0.33, and implied a mass function of 9.7 solar masses. We observed evidence for an accretion disk, a correlation between measured spin-up rate and flux, which was fitted to obtain a distance estimate of 9.5 +/- 2.9 kpc. XTE J1946+274 remained active from 1998 September to 2001 July, undergoing 13 outbursts that were not locked in orbital phase. Comparing RXTE Proportional Counter Array observations from the initial bright outburst in 1998 and the last pair of outbursts in 2001, we found energy and intensity-dependent pulse profile variations in both outbursts and hardening spectra with increasing intensity during the fainter 2001 outbursts. In 2001 July, optical H alpha observations indicated that a density perturbation appeared in the Be disk as the X-ray outbursts ceased. We propose that the equatorial plane of the Be star is inclined with respect to the orbital plane in this system and that this inclination may be a factor in the unusual outburst behavior of the system.

EPIC Study of Two Enigmatic Sources: The Mouse and SNR 359.1-0.5

NASA Technical Reports Server (NTRS)

Pavlov, George

2004-01-01

The objective of the original proposal was to observe the Mouse pulsar wind nebula (associated with PSR J1744-2958) and the nearby supernova remnant G359.1-0.5, where the pulsar was probably born, with the XMM-Newton observatory to study the properties of these objects. SNR G359.1-0.5 was accepted as a Category C target and has not been observed. The Mouse was observed on April 27,2003 for 52 ks. The image analysis has shown that the Mouse is extended in the East-West direction, possibly along the direction of the pulsar's proper motion. The spectrum of this pulsar wind nebula can be described as an absorbed power law with the photon index GAMMA = 1.9 plus or minus 0.1, effective hydrogen column density n(sub H) = (2.6 plus or minus 0.1) x 10(exp 22) per square centimeter, and flux F = 1.8 x 10(exp -11) erg per square centimeter per second in the 1-10 keV energy range. Based on the n(sub H) value, the distance to the source is about 5 kpc, which results in the luminosity 3.7 x 10(exp 34) erg per second. We conclude that PSR J1744-2958 and the Mouse are not physically associated with G359.1-0.5, which lies at a larger distance. In addition to the Mouse, we also detected two Low-Mass X-ray Binaries, SLX 1744-299 and 1744-300, in the EPIC MOS and PN fields of view. The latter of these objects showed a Type I X-ray burst during our observation, with a rise time of 5 s and decay time of 60 s. A very strong pileup during the burst made the analysis of the burst properties unreliable. The spectral analysis of the persistent radiation from SLX 1744-299 and 1744-300 yields the hydrogen column densities of 3.2 plus or minus 0.1 and (3.6 plus or minus 0.2) x 10(exp 22) per square centimeter, respectively, which suggests that the sources are close to the Galactic center (d = 8-9 kpc). The spectra can be reasonably well fitted with a blackbody plus thin disk model, with the blackbody temperatures of 1.7 plus or minus 0.2 and 1.8 plus or minus 0.2 keV, respectively.

A Reevaluation of the Morphology, Paleoecology, and Phylogenetic Relationships of the Enigmatic Walrus Pelagiarctos

PubMed Central

Boessenecker, Robert W.; Churchill, Morgan

2013-01-01

Background A number of aberrant walruses (Odobenidae) have been described from the Neogene of the North Pacific, including specialized suction-feeding and generalist fish-eating taxa. At least one of these fossil walruses has been hypothesized to have been a specialized predator of other marine mammals, the middle Miocene walrus Pelagiarctos thomasi from the Sharktooth Hill Bonebed of California (16.1–14.5 Ma). Methodology/Principal Findings A new specimen of Pelagiarctos from the middle Miocene “Topanga” Formation of southern California (17.5–15 Ma) allows a reassessment of the morphology and feeding ecology of this extinct walrus. The mandibles of this new specimen are robust with large canines, bulbous premolars with prominent paraconid, metaconid, hypoconid cusps, crenulated lingual cingula with small talonid basins, M2 present, double-rooted P3–M1, single-rooted P1 and M2, and a P2 with a bilobate root. Because this specimen lacks a fused mandibular symphysis like Pelagiarctos thomasi, it is instead referred to Pelagiarctos sp. This specimen is more informative than the fragmentary holotype of Pelagiarctos thomasi, permitting Pelagiarctos to be included within a phylogenetic analysis for the first time. Analysis of a matrix composed of 90 cranial, dental, mandibular and postcranial characters indicates that Pelagiarctos is an early diverging walrus and sister to the late Miocene walrus Imagotaria downsi. We reevaluate the evidence for a macropredatory lifestyle for Pelagiarctos, and we find no evidence of specialization towards a macrophagous diet, suggesting that Pelagiarctos was a generalist feeder with the ability to feed on large prey. Conclusions/Significance This new specimen of Pelagiarctos adds to the knowledge of this problematic taxon. The phylogenetic analysis conclusively demonstrates that Pelagiarctos is an early diverging walrus. Pelagiarctos does not show morphological specializations associated with macrophagy, and was likely a generalist predator, feeding on fish, invertebrates, and the occasional warm-blooded prey item. PMID:23342129

Creativity and mood disorders: The enigmatic case of Isaak Il'ich Levitan (1860-1900).

PubMed

Lerner, Vladimir; Margolin, Jacob; Witztum, Eliezer

2017-05-01

Isaak Levitan (1860-1900) was one of Russia's most influential landscape artists. He lived a very short life, only 40 years, but left more than 1000 paintings. He suffered from mood fluctuations, and died as a result of serious heart disease. After an introduction related to the issue of creativity and mental disorders, a short biography of Levitan's life is outlined, followed by some examples of his mood and behavior. A section on the mood's reflection in Levitan's professional work is followed by a description of his romantic loves and disappointments and his relationship with his contemporary Russian, the writer Anton Chekhov.

New Eocene damselflies and first Cenozoic damsel-dragonfly of the isophlebiopteran lineage (Insecta: Odonata).

PubMed

Garrouste, Romain; Nel, André

2015-10-09

The study of a new specimen of Petrolestes hendersoni from the Eocene Green Formation allows a more precise description of the enigmatic damselfly and the diagnosis of the Petrolestini. Petrolestes messelensis sp. nov. is described from the Eocene Messel Formation in Germany, extending the distribution of the Petrolestini to the European Eocene. The new damsel-dragonfly family Pseudostenolestidae is described for the new genus and species Pseudostenolestes bechlyi, from the Eocene Messel Formation. It is the first Cenozoic representative of the Mesozoic clade Isophlebioptera.

Insight into the growth dynamics and systematic affinities of the Late Cretaceous Gargantuavis from bone microstructure

NASA Astrophysics Data System (ADS)

Chinsamy, Anusuya; Buffetaut, Eric; Canoville, Aurore; Angst, Delphine

2014-05-01

Enigmatic avialan remains of Gargantuavis philoinos from the Ibero-Armorican island of the Late Cretaceous European archipelago (Southern France) led to a debate concerning its taxonomic affinities. Here, we show that the bone microstructure of Gargantuavis resembles that of Apteryx, the extinct emeids and Megalapteryx from New Zealand, and indicates that like these slow-growing terrestrial birds, it took several years to attain skeletal maturity. Our findings suggest that the protracted cyclical growth in these ornithurines may have been in response to insular evolution.

Syntheses and Biological Studies of Marine Terpenoids Derived from Inorganic Cyanide

PubMed Central

Schnermann, Martin J.; Shenvi, Ryan A.

2015-01-01

Isocyanoterpenes (ICTs) are marine natural products biosynthesized through an unusual pathway that adorns terpene scaffolds with nitrogenous functionality derived from cyanide. The appendage of nitrogen functional groups–isonitriles in particular–onto stereochemically-rich carbocyclic ring systems provides enigmatic, bioactive molecules that have required innovative chemical syntheses. This review discusses the challenges inherent to the synthesis of this diverse family and details the development of the field. We also present recent progress in isolation and discuss key aspects of the remarkable biological activity of these compounds. PMID:25514696

Trigger events: enviroclimatic coupling of Ebola hemorrhagic fever outbreaks

NASA Technical Reports Server (NTRS)

Pinzon, Jorge E.; Wilson, James M.; Tucker, Compton J.; Arthur, Ray; Jahrling, Peter B.; Formenty, Pierre

2004-01-01

We use spatially continuous satellite data as a correlate of precipitation within tropical Africa and show that the majority of documented Ebola hemorrhagic fever outbreaks were closely associated with sharply drier conditions at the end of the rainy season. We propose that these trigger events may enhance transmission of Ebola virus from its cryptic reservoir to humans. These findings suggest specific directions to help understand the sylvatic cycle of the virus and may provide early warning tools to detect possible future outbreaks of this enigmatic disease.

Study on interaction between induced and natural fractures by extended finite element method

NASA Astrophysics Data System (ADS)

Xu, DanDan; Liu, ZhanLi; Zhuang, Zhuo; Zeng, QingLei; Wang, Tao

2017-02-01

Fracking is one of the kernel technologies in the remarkable shale gas revolution. The extended finite element method is used in this paper to numerically investigate the interaction between hydraulic and natural fractures, which is an important issue of the enigmatic fracture network formation in fracking. The criteria which control the opening of natural fracture and crossing of hydraulic fracture are tentatively presented. Influence factors on the interaction process are systematically analyzed, which include the approach angle, anisotropy of in-situ stress and fluid pressure profile.

A re-description of the fossil damselfly Eolestes syntheticus Cockerell, 1940 (Odonata: Zygoptera: Eolestidae n. fam.) with description of new taxa from the Eocene of North America.

PubMed

Greenwalt, Dale E; Bechly, Günter

2014-11-24

The enigmatic species Eolestes syntheticus Cockerell, 1940, from the Early Eocene of North America, previously attributed to the lestoid family Synlestidae, is re-examined in light of the discovery of new material from the Middle Eocene Kishenehn Formation in northwestern Montana. E. syntheticus and a new species, Eolestes ramosus sp. n., are attributed to a new family Eolestidae fam. n.. In addition, a new genus and species very closely related to Lestidae but assigned to family unknown, Lutetialestes uniformis sp. n., is described from the Kishenehn Formation.

Aspergillus fumigatus Trehalose-Regulatory Subunit Homolog Moonlights To Mediate Cell Wall Homeostasis through Modulation of Chitin Synthase Activity.

PubMed

Thammahong, Arsa; Caffrey-Card, Alayna K; Dhingra, Sourabh; Obar, Joshua J; Cramer, Robert A

2017-04-25

Trehalose biosynthesis is found in fungi but not humans. Proteins involved in trehalose biosynthesis are essential for fungal pathogen virulence in humans and plants through multiple mechanisms. Loss of canonical trehalose biosynthesis genes in the human pathogen Aspergillus fumigatus significantly alters cell wall structure and integrity, though the mechanistic link between these virulence-associated pathways remains enigmatic. Here we characterize genes, called tslA and tslB , which encode proteins that contain domains similar to those corresponding to trehalose-6-phosphate phosphatase but lack critical catalytic residues for phosphatase activity. Loss of tslA reduces trehalose content in both conidia and mycelia, impairs cell wall integrity, and significantly alters cell wall structure. To gain mechanistic insights into the role that TslA plays in cell wall homeostasis, immunoprecipitation assays coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to reveal a direct interaction between TslA and CsmA, a type V chitin synthase enzyme. TslA regulates not only chitin synthase activity but also CsmA sub-cellular localization. Loss of TslA impacts the immunopathogenesis of murine invasive pulmonary aspergillosis through altering cytokine production and immune cell recruitment. In conclusion, our data provide a novel model whereby proteins in the trehalose pathway play a direct role in fungal cell wall homeostasis and consequently impact fungus-host interactions. IMPORTANCE Human fungal infections are increasing globally due to HIV infections and increased use of immunosuppressive therapies for many diseases. Therefore, new antifungal drugs with reduced side effects and increased efficacy are needed to improve treatment outcomes. Trehalose biosynthesis exists in pathogenic fungi and is absent in humans. Components of the trehalose biosynthesis pathway are important for the virulence of human-pathogenic fungi, including Aspergillus fumigatus

Processing of Presolar Grains around Post-Asymptotic Giant Branch Stars: Silicon Carbide as the Carrier of the 21 Micron Feature

NASA Astrophysics Data System (ADS)

Speck, Angela K.; Hofmeister, Anne M.

2004-01-01

Some proto-planetary nebulae (PPNs) exhibit an enigmatic feature in their infrared spectra at ~21 μm. This feature is not seen in the spectra of either the precursors to PPNs, the asymptotic giant branch (AGB) stars, or the successors of PPNs, ``normal'' planetary nebulae (PNs). However, the 21 μm feature has been seen in the spectra of PNs with Wolf-Rayet central stars. Therefore, the carrier of this feature is unlikely to be a transient species that only exists in the PPN phase. This feature has been attributed to various molecular and solid-state species, none of which satisfy all constraints, although titanium carbide (TiC) and polycyclic aromatic hydrocarbons (PAHs) have seemed the most viable. We present new laboratory data for silicon carbide (SiC) and show that it has a spectral feature that is a good candidate for the carrier of the 21 μm feature. The SiC spectral feature appears at approximately the same wavelength (depending on the polytype/grain size) and has the same asymmetric profile as the observed astronomical feature. We suggest that processing and cooling of the SiC grains known to exist around carbon-rich AGB stars are responsible for the emergence of the enigmatic 21 μm feature. The emergence of this feature in the spectra of post-AGB stars demonstrates the processing of dust due to the changing physical environments around evolving stars.

The temporal distribution of seismic radiation during deep earthquake rupture

USGS Publications Warehouse

Houston, H.; Vidale, J.E.

1994-01-01

The time history of energy release during earthquakes illuminates the process of failure, which remains enigmatic for events deeper than about 100 kilometers. Stacks of teleseismic records from regional arrays for 122 intermediate (depths of 100 to 350 kilometers) and deep (depths of 350 to 700 kilometers) earthquakes show that the temporal pattern of short-period seismic radiation has a systematic variation with depth. On average, for intermediate depth events more radiation is released toward the beginning of the rupture than near the end, whereas for deep events radiation is released symmetrically over the duration of the event, with an abrupt beginning and end of rupture. These findings suggest a variation in the style of rupture related to decreasing fault heterogeneity with depth.The time history of energy release during earthquakes illuminates the process of failure, which remains enigmatic for events deeper than about 100 kilometers. Stacks of teleseismic records from regional arrays for 122 intermediate (depths of 100 to 350 kilometers) and deep (depths of 350 to 700 kilometers) earthquakes show that the temporal pattern of short-period seismic radiation has a systematic variation with depth. On average, for intermediate depth events more radiation is released toward the beginning of the rupture than near the end, whereas for deep events radiation is released symmetrically over the duration of the event, with an abrupt beginning and end of rupture. These findings suggest a variation in the style of rupture related to decreasing fault heterogeneity with depth.

Amphibian and reptile declines over 35 years at La Selva, Costa Rica.

PubMed

Whitfield, Steven M; Bell, Kristen E; Philippi, Thomas; Sasa, Mahmood; Bolaños, Federico; Chaves, Gerardo; Savage, Jay M; Donnelly, Maureen A

2007-05-15

Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibian species are globally threatened, and over 120 species have likely suffered global extinction since 1980. Most alarmingly, many rapid declines and extinctions are occurring in pristine sites lacking obvious adverse effects of human activities. The causes of these "enigmatic" declines remain highly contested. Still, lack of long-term data on amphibian populations severely limits our understanding of the distribution of amphibian declines, and therefore the ultimate causes of these declines. Here, we identify a systematic community-wide decline in populations of terrestrial amphibians at La Selva Biological Station, a protected old-growth lowland rainforest in lower Central America. We use data collected over 35 years to show that population density of all species of terrestrial amphibians has declined by approximately 75% since 1970, and we show identical trends for all species of common reptiles. The trends we identify are neither consistent with recent emergence of chytridiomycosis nor the climate-linked epidemic hypothesis, two leading putative causes of enigmatic amphibian declines. Instead, our data suggest that declines are due to climate-driven reductions in the quantity of standing leaf litter, a critical microhabitat for amphibians and reptiles in this assemblage. Our results raise further concerns about the global persistence of amphibian populations by identifying widespread declines in species and habitats that are not currently recognized as susceptible to such risks.

Hairless mutation: a driving force of humanization from a human–ape common ancestor by enforcing upright walking while holding a baby with both hands

PubMed Central

Sutou, Shizuyo

2012-01-01

Three major characteristics distinguish humans from other primates: bipedality, practical nakedness, and the family as a social unit. A hairless mutation introduced into the chimpanzee/human last common ancestor (CLCA) 6 million years ago (Mya) diverged hairless human and hairy chimpanzee lineages. All primates except humans can carry their babies without using their hands. A hairless mother would be forced to stand and walk upright. Her activities would be markedly limited. The male partner would have to collect food and carry it to her by hand to keep her and their baby from starving; irresponsible and selfish males could not have left their offspring. The mother would have sexually accepted her partner at any time as a reward for food. Sexual relations irrespective of estrus cycles might have strengthened the pair bond. Molecular and paleontological dating indicates that CLCA existed 6 Mya, and early hominin fossils show that they were bipeds, indicating that humanization from CLCA occurred rapidly. A single mutation in animals with scalp hair is known to induce hairless phenotype (ectodermal dysplasia). Bipedalism and hairlessness are disadvantageous traits; only those who could survive trials and tribulations in cooperation with family members must have been able to evolve as humans. PMID:22404045

Recolonization of macrofauna in unpolluted sands placed in a polluted yachting harbour: A field approach using experimental trays

NASA Astrophysics Data System (ADS)

Guerra-García, J. M.; García-Gómez, J. C.

2009-01-01

A field experiment using trays was conducted at Ceuta's yachting harbour, North Africa, to study the effect in recolonization of placing trays with unpolluted defaunate sediments (fine and gross sands with low contents of organic matter) inside an enclosed yachting harbour characterized by high percentages of silt and clay and high concentrations of organic matter. Sediment recolonization in the trays was mainly undertaken by the species living naturally at the yachting harbour, which recolonized both uncontaminated gross and fine sand trays (such as the crustaceans Corophium runcicorne, Corophium sextonae and Nebalia bipes, the mollusc Parvicardium exiguum and the polychaete Pseudomalacoceros tridentata). However, other species like the polychaetes Cirriformia tentaculata and Platynereis dumerilii, although also abundant in the yachting harbour, were unable to colonize the trays through transport of larvae and/or adults in the water column. The recolonization was very quick, and after the first month, the values of abundance, species richness, diversity and evenness were similar in the experimental trays and in the reference area (yachting harbour). Although the multivariate analysis showed that the species composition differed between the trays and the reference area, there were no significant differences in recolonization of gross and fine sands, indicating that other factors different from the granulometry are modulating the recolonization patterns.

[The temporo-mandibular articulation].

PubMed

Dargaud, J; Vinkka-Puhakka, H

2004-04-01

The standing posture of humans has created both morphological and functional adaptations in the temporo-mandibular joint and the masticatory function. This biped state is the one of the most important characteristic of human evolution. It is furthermore the agent determining most of the functional changes in the whole body. This survey will be carried out in several levels including, a descriptive anatomy, biomechanics, radiological imaging, functioning in the articulation of TMJ. The descriptive anatomic picture will be obtained by the traditional dissection techniques. 20 TMJ joints are dissected from 10 cadavers: 7 cadavers, 65-75 year old, 3 cadavers, 60-65 year old. The x-rays are lateral view and the subjects of the radiological imaging are young's, adults and olds: 1, 3 y-old Male; 1, 7 y-old Female; 1, 14 y-old Female; 10, 19-23 y-old Male; 1, 26 y-old Female; 1, 34 y-old Male; 1, 75 y-old Female. The anatomic elements in the TMJ well resembled the ones described in the literature of the capsule, the ligament, the masticator muscles (masseter, temporal, medial and lateral pterygoids). The temporo-mandibular ligament proved to be difficult to separate from the capsule in some of the specimens. Sometimes it was not always found after a dissection.

Unusual presentation of hidradenitis suppurativa with massive enlargement of penis.

PubMed

Baughman, Steven M; Cespedes, R Duane

2004-08-01

Hidradenitis suppurativa is a chronic, recurrent inflammatory disease affecting the cutaneous apocrine glands and resulting in their obstruction. This enigmatic disease causes recurrent episodes of infection, edema, scarring, and fibrosis of surrounding tissues. We present the case of a 55-year-old man with two decades of inguinal hidradenitis suppurativa that resulted in extensive penile subcutaneous lymphedema and enlargement secondary to scarring and obstructive lymphadenopathy. Reconstructive phalloplasty to restore normal penile function was required. Minimal recurrent induration, normal cutaneous sensation, and normal voiding and erectile function were noted at 3 years of follow-up.

New Concepts in Complex Regional Pain Syndrome

PubMed Central

Tajerian, Maral; Clark, J David

2015-01-01

SYNOPSIS Despite the severe pain and disability associated with Complex Regional Pain Syndrome (CRPS), our lack of understanding of the pathophysiological mechanisms supporting this enigmatic condition prevents the rational design of new therapies, a situation that is frustrating both to the physician and the patient. The following review will highlight some of the mechanisms thought to be involved in the pathophysiology of CRPS in preclinical models and CRPS patients, with the ultimate goal that understanding these mechanisms will lead to the design of efficacious, mechanism-based treatments available to the clinic. PMID:26611388

Old Dad Chiro: his thoughts, words, and deeds

PubMed Central

Brown, Myron D.

2010-01-01

Objective This article offers the author's opinions about some of the thoughts, words, and deeds of the profession's founder, Daniel David Palmer. Discussion Reviewing D.D. Palmer's writings is challenging because he was the discoverer and founder of a developing profession and therefore his thoughts and words were rapidly evolving. Statements made by Palmer without judicious consideration of context could easily be misunderstood. Conclusion D.D. Palmer was individualistic and enigmatic. This commentary provides a look at the whole in an attempt to reveal the character and spirit of the founder. PMID:22693470

Spermidine boosts autophagy to protect from synapse aging.

PubMed

Bhukel, Anuradha; Madeo, Frank; Sigrist, Stephan J

2017-02-01

All animals form memories to adapt their behavior in a context-dependent manner. With increasing age, however, forming new memories becomes less efficient. While synaptic plasticity promotes memory formation, the etiology of age-induced memory formation remained enigmatic. Previous work showed that simple feeding of polyamine spermidine protects from age-induced memory impairment in Drosophila. Most recent work now shows that spermidine operates directly at synapses, allowing for an autophagy-dependent homeostatic regulation of presynaptic specializations. How exactly autophagic regulations intersect with synaptic plasticity should be an interesting subject for future research.

Assessing the geologic and climatic forcing of biodiversity and evolution surrounding the Gulf of California

USGS Publications Warehouse

Dolby, Greer; Bennett, Scott E. K.; Lira-Noriega, Andres; Wilder, Benjamin T.; Munguia-Vega, Adrian

2015-01-01

For almost a century the Baja California peninsula (Peninsula), Gulf of California (Gulf), and broader Sonoran Desert region (figure 1) have drawn geologists and biologists alike to study its unique physical and evolutionary processes (e.g., Wittich 1920; Darton 1921; Nelson 1921; Johnston 1924; Beal 1948; Durham and Allison 1960). The challenge remains to untangle the long, intricate, and at times enigmatic geological and climatological histories that have shaped the high levels of endemism and biodiversity observed in the region today (Van Devender 1990; Grismer 2000; Riddle et al. 2000).

Burning mouth syndrome.

PubMed

Thoppay, Jaisri R; De Rossi, Scott S; Ciarrocca, Katharine N

2013-07-01

Burning mouth syndrome (BMS) is a chronic condition that is characterized by burning symptoms of the oral mucosa without obvious clinical examination findings. This syndrome has complex characteristics, but its cause remains largely enigmatic, making treatment and management of patients with BMS difficult. Despite not being accompanied by evident organic changes, BMS can significantly reduce the quality of life for such patients. Therefore, it is incumbent on dental professionals to diagnose and manage patients with BMS as a part of comprehensive care. Copyright © 2013. Published by Elsevier Inc.

Women stereotypes in Shi Zhecun's short stories.

PubMed

Rosenmeier, Christopher

2010-01-01

This article analyses the representation of women in two 1933 short story collections by Shi Zhecun: An Evening of Spring Rain and Exemplary Conduct of Virtuous Women. It discusses how the New Woman image was a site of contestation in Republican China, and argues that Shi Zhecun’s short stories contain four basic stereotypes: the enigmatic woman, the estranged wife, the prostitute, and the inhibited woman. Using these narratives of women and how they were perceived by men, Shi Zhecun deconstructed the New Woman image by subverting the various ways modernity was projected onto women.

O-acetylserine (thiol) lyase: an enigmatic enzyme of plant cysteine biosynthesis revisited in Arabidopsis thaliana.

PubMed

Wirtz, Markus; Droux, Michel; Hell, Rüdiger

2004-08-01

The synthesis of cysteine is positioned at a decisive stage of assimilatory sulphate reduction, marking the fixation of inorganic sulphide into a carbon skeleton. O-acetylserine (thiol) lyase (OAS-TL) catalyses the reaction of inorganic sulphide with O-acetylserine (OAS). Despite its prominent position in the pathway OAS-TL is generally regarded as a non-limiting enzyme without regulatory function, due to low substrate affinities and semi-constitutive expression patterns. To resolve this apparent contradiction, the kinetic properties of three OAS-TLs from Arabidopsis thaliana, localized in the cytosol (A), plastids (B), and mitochondria (C), were analysed. The recombinant expressed OAS-TLs were purified to apparent homogeneity without any fusion tag to maintain their native forms. The proteins displayed high specific activities of 550-900 micromol min(-1) mg(-1). Using an improved and highly sensitive assay method for cysteine determination, the apparent K(m)(sulphide) was 3-6 microM for OAS-TL A, B, and C and thus 10-100 times lower than previously reported for plant OAS-TLs. K(m)(OAS) was between 310 microM and 690 microM for OAS-TL isoform A, B, and C, whereas the apparent dissociation binding constant for OAS was much lower (K(d)<1 microM OAS). A HPLC method was developed for OAS quantification that revealed fast increases of the cellular OAS concentration in response to sulphate deprivation. The observed fluctuations of intracellular OAS concentrations, combined with the OAS dissociation constant and the catalytic properties of OAS-TL, support the model of a dynamic cysteine synthesis system with regulatory function as can be expected from the position of the reaction in the sulphur assimilation pathway.

Spectacular Oscillations in Plant Isoprene Emission under Transient Conditions Explain the Enigmatic CO2 Response.

PubMed

Rasulov, Bahtijor; Talts, Eero; Niinemets, Ülo

2016-12-01

Plant isoprene emissions respond to light and temperature similarly to photosynthesis, but CO 2 dependencies of isoprene emission and photosynthesis are profoundly different, with photosynthesis increasing and isoprene emission decreasing with increasing CO 2 concentration due to reasons not yet understood. We studied isoprene emission, net assimilation rate, and chlorophyll fluorescence under different CO 2 and O 2 concentrations in the strong isoprene emitter hybrid aspen (Populus tremula × Populus tremuloides), and used rapid changes in ambient CO 2 or O 2 concentrations or light level to induce oscillations. As isoprene-emitting species support very high steady-state chloroplastic pool sizes of the primary isoprene substrate, dimethylallyl diphosphate (DMADP), which can mask the effects of oscillatory dynamics on isoprene emission, the size of the DMADP pool was experimentally reduced by either partial inhibition of isoprenoid synthesis pathway by fosmidomycin-feeding or by changes in ambient gas concentrations leading to DMADP pool depletion in intact leaves. In feedback-limited conditions observed at low O 2 and/or high CO 2 concentration under which the rate of photosynthesis is governed by the limited rate of ATP and NADPH formation due to low chloroplastic phosphate levels, oscillations in photosynthesis and isoprene emission were repeatedly induced by rapid environmental modifications in both partly fosmidomycin-inhibited leaves and in intact leaves with in vivo reduced DMADP pools. The oscillations in net assimilation rate and isoprene emission in feedback-inhibited leaves were in the same phase, and relative changes in the pools of photosynthetic metabolites and DMADP estimated by in vivo kinetic methods were directly proportional through all oscillations induced by different environmental perturbations. We conclude that the oscillations in isoprene emission provide direct experimental evidence demonstrating that the response of isoprene emission to changes in ambient gas concentrations is controlled by the chloroplastic reductant supply. © 2016 American Society of Plant Biologists. All Rights Reserved.

Hahajima Seamount: an enigmatic tectonic block at the junction between Izu-Bonin and Mariana Trench

NASA Astrophysics Data System (ADS)

Tokunaga, W.; Fujioka, K.; Yokose, H.

2005-12-01

The Hahajima Seamount located at the junction between Izu-Bonin and Mariana forearc slopes, represents a notable rectangular shape and consists of various kinds of rocks. An elaborated bathymetric swath mapping with geophysical measurements and dredge hauls showed the Hahajima Seamount is cut by two predominating lineaments, NE-SW and NW-SE. These lineaments are of faults based on the topographic cross sections and three-dimensional view (Whale's-eye view). The former lineament is parallel to the transform faults of the Parece Vela Basin in the Philippine Sea whereas the latter is to the nearby transform fault on the subducting Pacific Plate underneath the Izu-Bonin arc-trench system. The rocks obtained from the Hahajima Seamount are ultramafic rocks mostly harzburgite, boninite, basalt, andesite, gabbro breccia and sedimentary rocks, which characterize an island arc and an ocean basin affinities. The gravity measurement and seismic reflection survey offer neither definite gravity anomaly at the seamount nor definite internal structures beneath the seamount. The NW-SE trending fault and small scale serpentine flows were observed during the JAMSTEC submersible Shinkai 2000 dives at the Hahajima Seamount. The rectangular shape, size of seamount, various kinds of rocks and all the geophysical measurements strongly support that the Hahajima Seamount is not a simple serpentine seamount but a tectonic block unlike previously believed that was controlled by various tectonic movements.

On the enigmatic Heterostomus curvipalpis Bigot, 1857, with a description of the pupa (Diptera, Brachycera).

PubMed

Coscarón, Sixto; Coscarón, María Del Carmen; Gil-Azevedo, Leonardo H

2013-02-20

The previously unknown pupa of Heterostomus curvipalpis Bigot is described. The morphology of the pupa of Heterostomus is compared with the pupae of Xylophagomorpha, Tabanomorpha and Stratiomyomorpha families, based on five characters, and its phylogenetic position is discussed. Currently placed in Xylophagidae, we conclude that the pupa of Heterostomus shares most characters with the pupae of Pelecorhynchidae.

Ancient phylogenetic divergence of the enigmatic African rodent Zenkerella and the origin of anomalurid gliding

PubMed Central

Fernández, David; Sallam, Hesham M.; Cronin, Drew T.; Esara Echube, José Manuel

2016-01-01

The “scaly-tailed squirrels” of the rodent family Anomaluridae have a long evolutionary history in Africa, and are now represented by two gliding genera (Anomalurus and Idiurus) and a rare and obscure genus (Zenkerella) that has never been observed alive by mammalogists. Zenkerella shows no anatomical adaptations for gliding, but has traditionally been grouped with the glider Idiurus on the basis of craniodental similarities, implying that either the Zenkerella lineage lost its gliding adaptations, or that Anomalurus and Idiurus evolved theirs independently. Here we present the first nuclear and mitochondrial DNA sequences of Zenkerella, based on recently recovered whole-body specimens from Bioko Island (Equatorial Guinea), which show unambiguously that Zenkerella is the sister taxon of Anomalurus and Idiurus. These data indicate that gliding likely evolved only once within Anomaluridae, and that there were no subsequent evolutionary reversals. We combine this new molecular evidence with morphological data from living and extinct anomaluromorph rodents and estimate that the lineage leading to Zenkerella has been evolving independently in Africa since the early Eocene, approximately 49 million years ago. Recently discovered fossils further attest to the antiquity of the lineage leading to Zenkerella, which can now be recognized as a classic example of a “living fossil,” about which we know remarkably little. The osteological markers of gliding are estimated to have evolved along the stem lineage of the Anomalurus–Idiurus clade by the early Oligocene, potentially indicating that this adaptation evolved in response to climatic perturbations at the Eocene–Oligocene boundary (∼34 million years ago). PMID:27602286

Revelations of X-ray spectral analysis of the enigmatic black hole binary GRS 1915+105

NASA Astrophysics Data System (ADS)

Peris, Charith; Remillard, Ronald A.; Steiner, James; Vrtilek, Saeqa Dil; Varniere, Peggy; Rodriguez, Jerome; Pooley, Guy

2016-01-01

Of the black hole binaries discovered thus far, GRS 1915+105 stands out as an exceptional source primarily due to its wild X-ray variability, the diversity of which has not been replicated in any other stellar-mass black hole. Although extreme variability is commonplace in its light-curve, about half of the observations of GRS1915+105 show fairly steady X-ray intensity. We report on the X-ray spectral behavior within these steady observations. Our work is based on a vast RXTE/PCA data set obtained on GRS 1915+105 during the course of its entire mission and 10 years of radio data from the Ryle Telescope, which overlap the X-ray data. We find that the steady observations within the X-ray data set naturally separate into two regions in a color-color diagram, which we refer to as steady-soft and steady-hard. GRS 1915+105 displays significant curvature in the Comptonization component within the PCA band pass suggesting significantly heating from a hot disk present in all states. A new Comptonization model 'simplcut' was developed in order to model this curvature to best effect. A majority of the steady-soft observations display a roughly constant inner radius; remarkably reminiscent of canonical soft state black hole binaries. In contrast, the steady-hard observations display a growing disk truncation that is correlated to the mass accretion rate through the disk, which suggests a magnetically truncated disk. A comparison of X-ray model parameters to the canonical state definitions show that almost all steady-soft observations match the criteria of either thermal or steep power law state, while the thermal state observations dominate the constant radius branch. A large portion (80%) of the steady-hard observations matches the hard state criteria when the disk fraction constraint is neglected. These results suggest that within the complexity of this source is a simpler underlying basis of states, which map to those observed in canonical black hole binaries. When represented in a color-color diagram, state assignments appear to map to ``A, B and C'' (Belloni et al. 2000) regions that govern fast variability cycles in GRS 1915+105 demonstrating a compelling link between short and long time scales in its phenomenology.

Enigmatic Isovaline: Investigating the Stability, Racemization, and Formation of a Non-biological Meteoritic Amino Acid

NASA Technical Reports Server (NTRS)

Hudson, Reggie; Moore, Marla; Lewis, Ariel; Dworkin, Jason

2008-01-01

Among the Murchison meteoritic amino acids, isovaline stands out as being both nonbiological (non-protein) and having a relatively high abundance. While approximately equal amounts of D- and L-isovaline have been reported in Murchison and other CM meteorites, the molecule's structure appears to prohibit its racemization in aqueous solutions. We recently have investigated the low-temperature solid-phase chemistry of both isovaline and valine with an eye toward each molecule's formation, stability, and possible interconversions of D and L enantiomers. Ion-irradiated isovaline- and valinecontaining ices were examined by IR spectroscopy and highly-sensitive liquid chromatography/time-of-flight mass spectral methods to assess both amino acid destruction and racemization. Samples were studied in the presence and in the absence of water-ice, and the destruction of both isovaline and valine was measured as a function of radiation dose. In addition, we have undertaken experiments to synthesize isovaline, valine, and their amino acid isomers by solid-phase radiation-chemical pathways other than the oft-invoked Strecker process. This presentation will review and summarize some of our recent findings. -- Our work has been supported by a grant to the Goddard Center for Astrobiology through the NASA Astrobiology Institute. Experiments were performed in the Cosmic Ice Laboratory (RLH, MHM, AL) and the Astrobiology Analytical Laboratory (JPD, DPG) at the NASA Goddard Space Flight Center.

Chandra Detects Enigmatic Point X-ray Sources in the Cat's Eye and the Helix Nebulae

NASA Astrophysics Data System (ADS)

Guerrero, M. A.; Gruendl, R. A.; Chu, Y.-H.; Kaler, J. B.; Williams, R. M.

2000-12-01

Central stars of planetary nebulae (PNe) with Teff greater than 100,000 K are expected to emit soft X-rays that peak below 0.1 keV. Chandra ACIS-S observations of the Cat's Eye Nebula (NGC 6543) and the Helix Nebula (NGC 7293) have detected point X-ray sources at their central stars. The point X-ray source at the central star of the Cat's Eye is both unknown previously and unexpected because the stellar temperature is only ~50,000 K. In contrast, the point X-ray source at the central star of the Helix was previously detected by ROSAT and its soft X-ray emission is expected because the stellar temperature is ~100,000 K. However, the Helix X-ray source also shows a harder X-ray component peaking at 0.8 keV that is unexpected and for which Chandra has provided the first high-resolution spectrum for detailed analysis. The spectra of the point X-ray sources in the Cat's Eye and the Helix show line features indicating an origin of thermal plasma emission. The spectrum of the Helix source can be fit by Raymond & Smith's model of plasma emission at ~9*E6 K. The spectrum of the Cat's Eye source has too few counts for a spectral fit, but appears to be consistent with plasma emission at 2-3*E6 K. The X-ray luminosities of both sources are ~5*E29 erg s-1. The observed plasma temperatures are too high for accretion disks around white dwarfs, but they could be ascribed to coronal X-ray emission. While central stars of PNe are not known to have coronae, the observed spectra are consistent with quiescent X-ray emission from dM flare stars. On the other hand, neither the central star of the Helix or the Cat's Eye are known to have a binary companion. It is possible that the X-rays from the Cat's Eye's central star originate from shocks in the stellar wind, but the central star of the Helix does not have a measurable fast stellar wind. This work is supported by the CXC grant number GO0-1004X.

Cryptic extinction of a common Pacific lizard Emoia impar (Squamata, Scincidae) from the Hawaiian Islands.

USGS Publications Warehouse

Fisher, Robert; Ineich, Ivan

2012-01-01

Most documented declines of tropical reptiles are of dramatic or enigmatic species. Declines of widespread species tend to be cryptic. The early (1900s) decline and extinction of the common Pacific skink Emoia impar from the Hawaiian Islands is documented here through an assessment of literature, museum vouchers and recent fieldwork. This decline appears contemporaneous with the documented declines of invertebrates and birds across the Hawaiian Islands. A review of the plausible causal factors indicates that the spread of the introduced big-headed ant Pheidole megacephala is the most likely factor in this lizard decline. The introduction and spread of a similar skink Lampropholis delicata across the islands appears to temporally follow the decline of E. impar, although there is no evidence of competition between these species. It appears that L. delicata is spreading to occupy the niche vacated by the extirpated E. impar. Further confusion exists because the skink E. cyanura, which is very similar in appearance to E. impar, appears to have been introduced to one site within a hotel on Kaua'i and persisted as a population at that site for approximately 2 decades (1970s–1990s) but is now also extirpated. This study highlights the cryptic nature of this early species extinction as evidence that current biogeographical patterns of non-charismatic or enigmatic reptiles across the Pacific may be the historical result of early widespread invasion by ants. Conservation and restoration activities for reptiles in the tropical Pacific should consider this possibility and evaluate all evidence prior to any implementation.

What do unicellular organisms teach us about DNA methylation?

PubMed

Harony, Hala; Ankri, Serge

2008-05-01

DNA methylation is an epigenetic hallmark that has been studied intensively in mammals and plants. However, knowledge of this phenomenon in unicellular organisms is scanty. Examining epigenetic regulation, and more specifically DNA methylation, in these organisms represents a unique opportunity to better understand their biology. The determination of their methylation status is often complicated by the presence of several differentiation stages in their life cycle. This article focuses on some recent advances that have revealed the unexpected nature of the epigenetic determinants present in protozoa. The role of the enigmatic DNA methyltransferase Dnmt2 in unicellular organisms is discussed.

Role of LRF/Pokemon in lineage fate decisions

PubMed Central

Lunardi, Andrea; Guarnerio, Jlenia; Wang, Guocan

2013-01-01

In the human genome, 43 different genes are found that encode proteins belonging to the family of the POK (poxvirus and zinc finger and Krüppel)/ZBTB (zinc finger and broad complex, tramtrack, and bric à brac) factors. Generally considered transcriptional repressors, several of these genes play fundamental roles in cell lineage fate decision in various tissues, programming specific tasks throughout the life of the organism. Here, we focus on functions of leukemia/lymphoma-related factor/POK erythroid myeloid ontogenic factor, which is probably one of the most exciting and yet enigmatic members of the POK/ZBTB family. PMID:23396304

Immunology of the Uterine and Vaginal Mucosae.

PubMed

Zhou, Jordan Z; Way, Sing Sing; Chen, Kang

2018-04-01

Along with the maintenance of symbiotic mutualism with commensal microbes and protection against invasive infections common to all mucosal barrier tissues, female reproductive tissues have additional, unique tasks that include dynamic cyclic cellular turnover in menstruation and immunological tolerance to genetically foreign fetal antigens in pregnancy. Here we review current knowledge on distinct features of the immune cells in female reproductive tissue with regard to antimicrobial host defense and adaptations to accommodate the fetus during pregnancy. Outstanding areas for future research to obtain new functional insights on this enigmatic mucosal barrier are also highlighted. Copyright © 2018 Elsevier Ltd. All rights reserved.

Possible Geological Records of the Symbiotic Binary R Aquarii's Historical Outbursts

NASA Astrophysics Data System (ADS)

Tanabe, Kenji

2015-08-01

R Aquarii, known as one of the most enigmatic variable stars, seems to experience several outbursts as suggested by its surrounding nebulosity. Fortunately,in Korean ancient official books two outbursts in A.D.1073 and 1074 are recorded precisely (both its position and brightness). These two events possibly coincide with the two prominent spikes of nitrate ion frozen in the ice core extracted in 2001 from the top of Dome Fuji(3810 mheight) at the Japanese Antarctic station.We shall discuss whether such a coincidence is plausible or not from the point of viw of time resolution and age determination.

[Music in the picture -- musical scores and other music-related pictorial elements in the visual artworks of schizophrenic patients].

PubMed

Simon, Mária

2015-01-01

Since the beginning of the 20th century music scores and other music releated pictoral elements have repeteadly appeared in psychotic patients' visual artworks. Interestingly, little attention was paid to these enigmatic forms of psychopathological art expression till the 1970s. This essay investigates the underlying psychopathology and the psychodynamic basis of musical elements applied in psychotic patients' visual art expression within a phenomenological- intersubjective framework integrating the art-historical context of the 20th century. As an illustration, artworks of the psychopathological art collection of the Department of Psychiatry and Psychotherapy, Medical Faculty, University of Pecs, Hungary are presented.

Juxtaoral organ of Chievitz: An innocuous organ to be known

PubMed Central

Bommanavar, Sushma Basavaraj; Hema, K N; Baad, Rajendra

2017-01-01

The Juxtaoral Organ of Chievitz is a normal anatomical structure located within the soft tissue in the buccotemporal fascia on the medial surface of the ascending ramus. This enigmatic vestigial structure is considered to be of neuroepithelial origin with no known function. As a matter of fact, JOOC is one of the most treacherous pitfalls in surgical pathology with respect to lesions in the head and neck area. Hence the basic aim of this short communication is to reveal the importance about this organ and enlighten the oral pathologist about this histopathological structure, thus preventing extensive and unnecessary investigations. PMID:28479708

The Charcot Foot in Diabetes

PubMed Central

Frykberg, Robert G.; Armstrong, David G.; Boulton, Andrew J.M.; Edmonds, Michael; Van, Georges Ha; Hartemann, Agnes; Game, Frances; Jeffcoate, William; Jirkovska, Alexandra; Jude, Edward; Morbach, Stephan; Morrison, William B.; Pinzur, Michael; Pitocco, Dario; Sanders, Lee; Wukich, Dane K.; Uccioli, Luigi

2011-01-01

The diabetic Charcot foot syndrome is a serious and potentially limb-threatening lower-extremity complication of diabetes. First described in 1883, this enigmatic condition continues to challenge even the most experienced practitioners. Now considered an inflammatory syndrome, the diabetic Charcot foot is characterized by varying degrees of bone and joint disorganization secondary to underlying neuropathy, trauma, and perturbations of bone metabolism. An international task force of experts was convened by the American Diabetes Association and the American Podiatric Medical Association in January 2011 to summarize available evidence on the pathophysiology, natural history, presentations, and treatment recommendations for this entity. PMID:21868781

Odontogenic keratocyst: What is in the name?

PubMed Central

Nayak, Meghanand T.; Singh, Anjali; Singhvi, Abhishek; Sharma, Rohit

2013-01-01

The classification of odontogenic cysts is complicated and can create confusion for both clinicians and pathologists. The odontogenic keratocyst (OKC) is an enigmatic developmental cyst that deserves special attention. It has characteristic histopathological and clinical features; but, what makes this cyst special is its aggressive behavior and high recurrence rate. Despite of many classifications and nomenclature, unfortunately the clinicians still have to face difficulties in the management of this commonly found jaw lesion. This article is an effort to provide an overview of various aspects of OKC with emphasis on nomenclature, recurrence, molecular aspects, and management of OKC. PMID:24082717

Cushing syndrome: update on testing.

PubMed

Raff, Hershel

2015-03-01

Endogenous hypercortisolism (Cushing syndrome) is one of the most enigmatic diseases in clinical medicine. The diagnosis and differential diagnosis of Cushing syndrome depend on proper laboratory evaluation. In this review, an update is provided on selected critical issues in the diagnosis and differential diagnosis of Cushing syndrome: the use of late-night salivary cortisol in initial diagnosis and for postoperative surveillance, and the use of prolactin measurement to improve the performance of inferior petrosal sinus sampling to distinguish Cushing disease from ectopic adrenocorticotropic hormone (ACTH) syndrome during differential diagnosis of ACTH-dependent Cushing syndrome. Copyright © 2015 Elsevier Inc. All rights reserved.

The bee's map of the e-vector pattern in the sky.

PubMed

Rossel, S; Wehner, R

1982-07-01

It has long been known that bees can use the pattern of polarized light in the sky as a compass cue even if they can see only a small part of the whole pattern. How they solve this problem has remained enigmatic. Here we show that the bees rely on a generalized celestial map that is used invariably throughout the day. We reconstruct this map by analyzing the navigation errors made by bees to which single e-vectors are displayed. In addition, we demonstrate how the bee's celestial map can be derived from the e-vector patterns in the sky.

1 Hz FLARING IN SAX J1808.4-3658: FLOW INSTABILITIES NEAR THE PROPELLER STAGE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patruno, Alessandro; Watts, Anna; Klein Wolt, Marc

2009-12-20

We present a simultaneous periodic and aperiodic timing study of the accreting millisecond X-ray pulsar SAX J1808.4-3658. We analyze five outbursts of the source and for the first time provide a full and systematic investigation of the enigmatic phenomenon of the 1 Hz flares observed during the final stages of some of the outbursts. We show that links between pulsations and 1 Hz flares might exist, and suggest that they are related with hydrodynamic disk instabilities that are triggered close to the disk-magnetosphere boundary layer when the system is entering the propeller regime.

Back to the future: Rational maps for exploring acetylcholine receptor space and time.

PubMed

Tessier, Christian J G; Emlaw, Johnathon R; Cao, Zhuo Qian; Pérez-Areales, F Javier; Salameh, Jean-Paul J; Prinston, Jethro E; McNulty, Melissa S; daCosta, Corrie J B

2017-11-01

Global functions of nicotinic acetylcholine receptors, such as subunit cooperativity and compatibility, likely emerge from a network of amino acid residues distributed across the entire pentameric complex. Identification of such networks has stymied traditional approaches to acetylcholine receptor structure and function, likely due to the cryptic interdependency of their underlying amino acid residues. An emerging evolutionary biochemistry approach, which traces the evolutionary history of acetylcholine receptor subunits, allows for rational mapping of acetylcholine receptor sequence space, and offers new hope for uncovering the amino acid origins of these enigmatic properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Burning Mouth Syndrome.

PubMed

Klasser, Gary D; Grushka, Miriam; Su, Nan

2016-08-01

Burning mouth syndrome (BMS) is an enigmatic, misunderstood, and under-recognized painful condition. Symptoms associated with BMS can be varied, thereby providing a challenge for practitioners and having a negative impact on oral health-related quality of life for patients. Management also remains a challenge for practitioners because it is currently only targeted for symptom relief without a definitive cure. There is an urgent need for further investigations to determine the efficacy of different therapies because this is the only way viable therapeutic options can be established for patients with this chronic and painful syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

Close-wedge osteotomy for bony locking stiffness of the elbow in Gorham disease patients: a case report.

PubMed

Wang, Hsien-Chung; Lin, Gau-Tyan

2004-05-01

Gorham disease is a so-called massive idiopathic osteolysis or vanishing bone disorder. Massive osteolysis remains an enigmatic condition that involves various skeletal locations and is caused by endothelial proliferation. The diagnosis is difficult and is established via the association of clinical, radiologic and histologic pictures. Treatment modalities yield variable results. We report a case of vanishing bone in the elbow joint and carpal bones following trauma. This 13-year-old boy complained of severe restricted motion and deformity of the right elbow. We managed the problem using arthroplasty with close-wedge osteotomy on the lateral condyle of the humerus.

KIC 8462852: Potential Repeat of the Kepler Day 1540 Dip in 2017 August

NASA Astrophysics Data System (ADS)

Bourne, Rafik; Gary, Bruce

2017-12-01

We report 33 V-band observations by the Hereford Arizona Observatory (HAO) of the enigmatic star KIC 8462852 during the two week period 3-17 August 2017. We find a striking resemblance of these observations to the Kepler day 1540 dip with HAO observations tracking the Kepler light curve (adjusted for egress symmetry). A possible explanation of this potential repeat transit is a brown dwarf and extensive ring system in a 1601-day eccentric orbit. We suggest this object may be detectable through radial velocity observations in October and November 2017, with an amplitude of ~ 1-2 kms-1.

Shaking the tyrant's bloody robe.

PubMed

Kiper, Jordan; Sosis, Richard

Group violence, despite much study, remains enigmatic. Its forms are numerous, its proximate causes myriad, and the interrelation of its forms and proximate causes poorly understood. We review its evolution, including preadaptations and selected propensities, and its putative environmental and psychological triggers. We then reconsider one of its forms, ethnoreligious violence, in light of recent discoveries in the behavioral and brain sciences. We find ethnoreligious violence to be characterized by identity fusion and by manipulation of religious traditions, symbols, and systems. We conclude by examining the confluence of causes and characteristics before and during Yugoslavia's wars of disintegration.

Variability of Young Stars: the Importance of Keeping an Eye on Children

NASA Astrophysics Data System (ADS)

Herbst, W.

2013-06-01

(Abstract only) I will review the state of our understanding of young stars with an emphasis on how and why they vary in brightness. The main causes of the variations will be reviewed, including the rotation of spotted weak-lined T Tauri stars, accretion onto classical T Tauri stars, the eruptive behavior of FUors, and the enigmatic variations of the UXors. The important role that amateurs have and will continue to play in these studies is highlighted. I will also discuss the latest results on two unusual young binaries, BM Orionis in the Trapezium asterism and KH 15D in NGC 2264.

Genetics and Genomics of Endometriosis

PubMed Central

Hansen, Keith A.; Eyster, Kathleen M.

2015-01-01

Endometriosis is a common cause of morbidity in women with an unknown etiology. Studies have demonstrated the familial nature of endometriosis and suggest that inheritance occurs in a polygenic/multifactorial fashion. Studies have attempted to define the gene or genes responsible for endometriosis through association or linkage studies with candidate genes or DNA mapping technology. A number of genomics studies have demonstrated significant alterations in gene expression in endometriosis. A more thorough understanding of the genetics and genomics of endometriosis will facilitate understanding the basic biology of the disease and open new inroads to diagnosis and treatment of this enigmatic condition. PMID:20436317

A taxonomic monograph of the genus Tylodinus Champion (Coleoptera: Curculionidae: Cryptorhynchinae: Tylodina) of Chiapas, Mexico.

PubMed

Luna-Cozar, Jesús; Anderson, Robert S; Jones, Robert W; León-Corté, Jorge L

2014-04-15

The species of the genus Tylodinus from the Mexican state of Chiapas are revised. We examined 989 specimens representing 36 species; 23 species are grouped into eight species groups with 13 species considered as Incertae sedis. A total of 32 species are described as new and one species is a new record for México. Species groups  (numbers of species in parentheses) and species are: Tylodinus buchanani species group (6) T. buchanani new species (type locality: Chiapas, Unión Juárez, Volcán Tacan), T. exiguus new species (type locality: Chiapas, Motozintla, 7 km SSW Motozintla de Mendoza), T. ixchel new species (type locality: Chiapas, Unión Juarez, Volcán Tacan), T. jonesi new species (type locality: Chiapas, Angel Albino Corzo, Reserva de la Biosfera el Triunfo, Campamento el Quetzal), T. variabilis new species (type locality: Chiapas, San Cristóbal de las Casas, Cerro Huitepec), T. wibmeri new species (type locality: Chiapas, Motozintla, 7 km SSW Motozintla de Mendoza); Tylodinus canaliculatus species group (3) T. canaliculatus Champion (Chiapas, Unión Juárez, Volcán Tacan, new record for  México), T. sepulturaensis new species (Type locality: Chiapas, Villa Corzo, Ejido Sierra Morena), T. triumforium new species (Type locality: Chiapas, La Concordia, 4 km SE Custepec); Tylodinus cavicrus species group (3) T. cavicrus Champion, T. pseudocavicrus new species (type locality: Chiapas, San Cristóbal de las Casas, Cerro Huitepec), T. rugosus new species (type locality: Chiapas, Villa Flores, Sierra Morena); Tylodinus coapillensis species group (2) T. coapillensis new species (type locality: Chiapas, Coapilla, ca. 10.5 km NE Coapilla), T. leoncortesi new species (type locality: Chiapas, Pueblo Nuevo Solistahuacán, La Yerbabuena); Tylodinus mutabilis species group (2) Tylodinus mutabilis new species (type locality: Chiapas, Villa Corzo, Ejido Sierra Morena), T. parvus new species (type locality: Chiapas, Trinitaria, Lagunas de Montebello); Tylodinus

A biomechanical analysis of upper extremity kinetics in children with cerebral palsy using anterior and posterior walkers.

PubMed

Konop, Katherine A; Strifling, Kelly M B; Wang, Mei; Cao, Kevin; Schwab, Jeffrey P; Eastwood, Daniel; Jackson, Scott; Ackman, Jeffrey D; Harris, Gerald F

2009-10-01

Upper extremity (UE) joint kinetics during aided ambulation is an area of research that is not well characterized in the current literature. Biped UE joints are not anatomically designed to be weight bearing, therefore it is important to quantify UE kinetics during assisted gait. This will help to better understand the biomechanical implications of UE weight bearing, and enable physicians to prescribe more effective methods for treatment and therapy, perhaps minimizing excessive loads and torques. To address this challenge, an UE model that incorporates both kinematics and kinetics has been developed for use with walkers instrumented with load cells. In this study, the UE joint kinetics are calculated for 10 children with cerebral palsy using both anterior and posterior walkers. Three-dimensional joint reaction forces and moments are fully characterized for the wrist, elbow, and shoulder (glenohumeral) joints for both walker types. Statistical analysis methods are used to quantify the differences in forces or moments between the two walker types. Comparisons showed no significant differences in kinetic joint parameters between walker types. Results from a power analysis of the current data are provided which may be useful for planning longer term clinical studies. If risk factors for UE joint pathology can be identified early, perhaps a change in gait training routine, walker prescription, or walker design could prevent further harm.

On the origin of avian air sacs.

PubMed

Farmer, C G

2006-11-01

For many vertebrates the lung is the largest and lightest organ in the body cavity and for these reasons can greatly affect an organism's shape, density, and its distribution of mass; characters that are important to locomotion. In this paper non-respiratory functions of the lung are considered along with data on the respiratory capacities and gas exchange abilities of birds and crocodilians to infer the evolutionary history of the respiratory systems of dinosaurs, including birds. From a quadrupedal ancestry theropod dinosaurs evolved a bipedal posture. Bipedalism is an impressive balancing act, especially for tall animals with massive heads. During this transition selection for good balance and agility may have helped shape pulmonary morphology. Respiratory adaptations arising for bipedalism are suggested to include a reduction in costal ventilation and the use of cuirassal ventilation with a caudad expansion of the lung into the dorsal abdominal cavity. The evolution of volant animals from bipeds required yet again a major reorganization in body form. With this transition avian air sacs may have been favored because they enhanced balance and agility in flight. Finally, I propose that these hypotheses can be tested by examining the importance of the air sacs to balance and agility in extant animals and that these data will enhance our understanding of the evolution of the respiratory system in archosaurs.

Control of constraint forces and trajectories in a rich sensory and actuation environment.

PubMed

Hemami, Hooshang; Dariush, Behzad

2010-12-01

A simple control strategy is proposed and applied to a class of non-linear systems that have abundant sensory and actuation channels as in living systems. The main objective is the independent control of constrained trajectories of motion, and control of the corresponding constraint forces. The peripheral controller is a proportional, derivative and integral (PID) controller. A central controller produces, via pattern generators, reference signals that are the desired constrained position and velocity trajectories, and the desired constraint forces. The basic tenet of the this hybrid control strategy is the use of two mechanisms: 1. linear state and force feedback, and 2. non-linear constraint velocity feedback - sliding mode feedback. The first mechanism can be envisioned as a high gain feedback systems. The high gain attribute imitates the agonist-antagonist co-activation in natural systems. The strategy is applied to the control of the force and trajectory of a two-segment thigh-leg planar biped leg with a mass-less foot cranking a pedal that is analogous to a bicycle pedal. Five computational experiments are presented to show the effectiveness of the strategy and the performance of the controller. The findings of this paper are applicable to the design of orthoses and prostheses to supplement functional electrical stimulation for support purposes in the spinally injured cases. Copyright © 2010 Elsevier Inc. All rights reserved.

The first well-preserved coelophysoid theropod dinosaur from Asia.

PubMed

You, Hai-Lu; Azuma, Yoichi; Wang, Tao; Wang, Ya-Ming; Dong, Zhi-Ming

2014-10-16

Coelophysoid dinosaurs represent the earliest major radiation of neotheropods. These small-to-medium-sized agile bipeds lived throughout much of Pangaea during the Late Triassic-arly Jurassic. Previously reported coelophysoid material from Asia (excluding the Gondwanan territory of India) is limited to two specimens that comprise only limb fragments. This paper describes a new genus and species of coelophysoid, Panguraptor lufengensis, from the Lower Jurassic Lufeng Formation of Yunnan Province, China. The new taxon is represented by a well-preserved skeleton, including the skull and lower jaw, the presacral vertebral column and partial ribs, the right scapula, a partial forelimb, part of the pelvic girdle, and an almost complete hind limb. It is distinguished from other coelophysoid theropods by the unique combination of the following three character states: 1) diagonal (rostrodorsal-caudoventral) ridge on lateral surface of maxilla, within antorbital fossa, 2) elliptical, laterally facing fenestra caudodorsal to aforementioned diagonal ridge, and 3) hooked craniomedial corner of distal tarsal IV. Cladistic analysis recovers Panguraptor lufengensis deeply nested within Coelophysoidea as a member of Coelophysidae, and it is more closely related to Coelophysis than to "Syntarsus". Panguraptor represents the first well-preserved coelophysoid theropod dinosaur from Asia, and provides fresh evidence supporting the hypothesis that terrestrial tetrapods tended to be distributed pan-continentally during the Early Jurassic.

Inside pyroclastic density currents - uncovering the enigmatic flow structure and transport behaviour in large-scale experiments

NASA Astrophysics Data System (ADS)

Breard, Eric C. P.; Lube, Gert

2017-01-01

Pyroclastic density currents (PDCs) are the most lethal threat from volcanoes. While there are two main types of PDCs (fully turbulent, fully dilute pyroclastic surges and more concentrated pyroclastic flows encompassing non-turbulent to turbulent transport) pyroclastic flows, which are the subject of the present study, are far more complex than dilute pyroclastic surges and remain the least understood type despite their far greater hazard, greater runout length and ability to transport vast quantities of material across the Earth's surface. Here we present large-scale experiments of natural volcanic material and gas in order to provide the missing quantitative view of the internal structure and gas-particle transport mechanisms in pyroclastic flows. We show that the outer flow structure with head, body and wake regions broadly resembles current PDC analogues of dilute gravity currents. However, the internal structure, in which lower levels consist of a concentrated granular fluid and upper levels are more dilute, contrasts significantly with the internal structure of fully dilute gravity currents. This bipartite vertical structure shows strong analogy to current conceptual models of high-density turbidity currents, which are responsible for the distribution of coarse sediment in marine basins and of great interest to the hydrocarbon industry. The lower concentrated and non-turbulent levels of the PDC (granular-fluid basal flow) act as a fast-flowing carrier for the more dilute and turbulent upper levels of the current (ash-cloud surge). Strong kinematic coupling between these flow parts reduces viscous dissipation and entrainment of ambient air into the lower part of the ash-cloud surge. This leads to a state of forced super-criticality whereby fast and destructive PDCs can endure even at large distances from volcanoes. Importantly, the basal flow/ash-cloud surge coupling yields a characteristically smooth rheological boundary across the non-turbulent/turbulent interface, as well as vertical velocity and density profiles in the ash-cloud surge, which strongly differ from current theoretical predictions. Observed generation of successive pulses of high dynamic pressure within the upper dilute levels of the PDC may be important to understand the destructive potential of PDCs. The experiments further show that a wide range in the degree of coupling between particle and gas phases is critical to the vertical and longitudinal segregation of the currents into reaches that have starkly contrasting sediment transport capacities. In particular, the formation of mesoscale turbulence clusters under strong particle-gas feedback controls vertical stratification inside the turbulent upper levels of the current (ash-cloud surge) and triggers significant transfers of mass and momentum from the ash-cloud surge onto the granular-fluid basal flow. These results open up new pathways to advance current computational PDC hazard models and to describe and interpret PDCs as well as other types of high-density gravity currents transported across the surfaces of Earth and other planets and across marine basins.

Taxonomic identity of two enigmatic aquatic snake populations (Squamata: Homalopsidae: Cerberus and Homalopsis) from southern Thailand.

PubMed

Pauwels, Olivier S G; Sumontha, Montri

2016-05-02

In their revision of the homalopsid genus Homalopsis Kuhl & Van Hasselt, Murphy et al. (2012) resurrected H. semizonata Blyth, 1855 and noted that ''Frith (1977) reported on two Homalopsis from Phuket, Thailand with 40 and 42 dorsal scale rows, and 159 and 162 ventrals-scale counts within the range of H. semizonata which is found along the same coast, about 900 km to the north''. Murphy et al. (2012), however, did not list H. semizonata from Thailand, and on their species' distribution map they indicated an interrogation mark along the southern coast of Myanmar and the southwestern coast of peninsular Thailand. It should be noted that Murphy et al. (2012) misread Frith: while one of the two specimens reported by Frith was indeed from Phuket (''from the rocky edge of a stream torrent in good forest east of Thalang, central Phuket Island''), the other was from ''Klong Nakha, 80 kilometeres [sic] south of Ranong in lowland rain forest with some clearings and dwellings'', thus in Ranong Province, closer to the border with Myanmar. Nabhitabhata et al. (2004) recognized a single Homalopsis species in Thailand, H. buccata, which they listed for numerous provinces, including Phuket, based on Frith's (1977) record. Among the two Homalopsis species recognized to occur in Thailand by Nabhitabhata and Chan-ard (2005), H. buccata and H. nigroventralis, none was recorded by them from Phuket Province, but H. buccata was listed from, among others, the neighbouring provinces of Phang-Nga and Ranong. Chuaynkern & Chuaynkern (2012) recognized the same two species, and listed H. buccata from, among others, the provinces of Phang-Nga, Phuket and Ranong. Cox et al. (2012) listed three Homalopsis for Thailand (H. buccata, H. mereljcoxi and H. nigroventralis), and indicated that H. mereljcoxi is the species occurring, a.o., in Phang-Nga, Phuket and Ranong provinces. Wallach et al. (2014) noted that H. semizonata lives in southern Myanmar near sea level, but also that it ''possibly occurs in Phuket''. Chan-ard et al. (2015), in their field guide whose reptile taxonomy is largely outdated (Pauwels & Grismer 2015), recognized only Homalopsis nigroventralis and H. buccata and the map for the latter indicates its presence in Phuket and Phang-Nga provinces. In the most recent synthesis on the family Homalopsidae, Murphy & Voris (2014) made however no mention of the possibility that H. semizonata occurs in Thailand. Because of the lack of voucher material, the identity of the Homalopsis living on the Indian Ocean coastal area of Thailand has thus remained poorly understood so far.

The biological soil crusts of the San Nicolas Island: Enigmatic algae from a geographically isolated ecosystem

USGS Publications Warehouse

Flechtner, V.R.; Johansen, J.R.; Belnap, J.

2008-01-01

Composite soil samples from 7 sites on San Nicolas Island were evaluated quantitatively and qualitatively for the presence of cyanobacteria and eukaryotic microalgae. Combined data demonstrated a rich algal flora with 19 cyanobacterial and 19 eukaryotic microalgal genera being identified, for a total of 56 species. Nine new species were identified and described among the cyanobacteria and the eukaryotic microalgae that were isolated: Leibleinia edaphica, Aphanothece maritima, Chroococcidiopsis edaphica, Cyanosarcina atroveneta, Hassallia californica, Hassallia pseudoramosissima, Microchaete terrestre, Palmellopsis californiens, and Pseudotetracystis compactis. Distinct distributional patterns of algal taxa existed among sites on the island and among soil algal floras of western North America. Some algal taxa appeared to be widely distributed across many desert regions, including Microcoleus vaginatus, Nostoc punctiforme, Nostoc paludosum, and Tolypothrix distorta, Chlorella vulgaris, Diplosphaera cf. chodatii, Myrmecia astigmatica, Myrmecia biatorellae, Hantzschia amphioxys, and Luticola mutica. Some taxa share a distinctly southern distribution with soil algae from southern Arizona, southern California, and Baja California (e.g., Scenedesmus deserticola and Eustigmatos magnus). The data presented herein support the view that the cyanobacterial and microalgal floras of soil crusts possess significant biodiversity, much of it previously undescribed.

A Continuing Analysis of Possible Activity Drivers for the Enigmatic Comet 29P/Schwassmann-Wachmann 1

NASA Astrophysics Data System (ADS)

Schambeau, Charles; Fernández, Yanga; Samarasinha, Nalin H.; Mueller, Beatrice E. A.; Sarid, Gal; Meech, Karen Jean; Woodney, Laura

2016-01-01

We present results from our effort to understand activity drivers in Comet 29P/Schwassmann-Wachmann 1 (SW1). In a nearly circular orbit around 6 AU, outside of the water-sublimation zone, SW1 is continuously active and experiences frequent outbursts. Our group's effort is focusing on finding constraints on physical and dynamical properties of SW1's nucleus and their incorporation into a thermophysical model [1,2] to explain this behavior. We are currently analyzing coma morphology of SW1 before, during, and after outburst placing constraints on the spin-pole direction, spin period, and surface areas of activity. In addition, we are using the thermal model to investigate if the continuous activity comes from one or multiple processes, such as the release of trapped supervolatiles during the amorphous to crystalline (A-C) water ice phase transition and/or the direct sublimation of pockets of supervolatile ices. The supervolatile ices may be primordial or from the condensation of gases released during the A-C phase transition. To explain the possibly quasi-periodic but frequent outbursts, we are looking into subsurface cavities where internal pressures can build, reaching and exceeding surrounding material strengths [3,4] and/or thermal waves reaching a pocket of supervolatile ices, causing a rapid increase in the sublimation rate. For all these phenomena, the model is constrained by comparing the output dust mass loss rate and its variability with what has been observed through optical imaging of the comet at various points in its orbit. We will present preliminary thermal modeling of a homogeneous progenitor nucleus that evolves into a body showing internal material layering, the generation of CO and CO2 ice pockets, and the production of outbursts, thus bringing us closer to explaining the behavior of this intriguing comet. [1] Sarid, G., et al.: 2005, PASP, 117, 843. [2] Sarid, G.: 2009, PhD Thesis, Tel Aviv Univ. [3] Gronkowski, P., 2014, Astron. Nachr./AN 2, No. 335, 124-134. [4] Gronkowski, P. and Wesolowski, M., 2015, MNRAS, 451, 3068-3077. We thank the NASA Outer Planets Research Program (NNX12AK50G) and the Center for Lunar and Asteroid Surface Science (CLASS, NNA14AB05A) for support of this work.

A Continuing Analysis of Possible Activity Drivers for the Enigmatic Comet 29P/Schwassmann-Wachmann 1

NASA Astrophysics Data System (ADS)

Schambeau, Charles Alfred; Fernandez, Yanga; Samarasinha, Nalin; Sarid, Gal; Mueller, Beatrice; Meech, Karen; Woodney, Laura

2015-11-01

We present results from our continuing effort to understand activity drivers in Comet 29P/Schwassmann-Wachmann 1 (SW1). While being in a nearly circular orbit around 6 AU, SW1 is continuously active and experiences frequent outbursts. Our group’s effort is focusing on finding constraints on physical and dynamical properties of SW1’s nucleus and their incorporation into a thermophysical model [1,2] to explain this behavior. Now we are analyzing coma morphology of SW1 before, during, and after outburst to place constraints on the spin-pole direction, spin period, and surface areas of activity (a spin period lower limit has been measured). Also, we are using the thermal model to investigate if the continuous activity comes from one or multiple processes, such as the release of trapped supervolatiles during the amorphous to crystalline (A-C) water ice phase transition and/or the direct sublimation of pockets of supervolatile ices, which may be primordial or from the condensation of gases released during the A-C phase transition. To explain the possibly quasi-periodic but frequent outbursts, we are looking into subsurface cavities where internal pressures can build, reaching and exceeding surrounding material strengths [3,4] and/or thermal waves reaching a pocket of supervolatile ices, causing a rapid increase in the sublimation rate. For all these phenomena, the model is constrained by comparing the output dust mass loss rate and its variability with what has been observed through optical imaging of the comet at various points in its orbit. We will present preliminary thermal modeling of a homogeneous progenitor nucleus that evolves into a body showing internal material layering, the generation of CO and CO2 ice pockets, and the production of outbursts, thus bringing us closer to explaining the behavior of this intriguing comet.[1] Sarid, G., et al.: 2005, PASP, 117, 843. [2] Sarid, G.: 2009, PhD Thesis, Tel Aviv Univ. [3] Gronkowski, P., 2014, Astron. Nachr./AN 2, No. 335, 124-134. [4] Gronkowski, P. and Wesolowski, M., 2015, MNRAS, 451, 3068-3077. We thank the NASA Outer Planets Research Program (NNX12AK50G) and the Center for Lunar and Asteroid Surface Science (CLASS, NNA14AB05A) for support of this work.

On the Recurrence of Enigmatic Nannoplankton Blooms in the Subtropical South Atlantic during the Early Oligocene

NASA Astrophysics Data System (ADS)

Shanks, L. V.; Kelly, D. C.; Meyers, S. R.

2015-12-01

Climatic cooling and expansion of Antarctic ice sheets was accompanied by a global reorganization in ocean circulation during the early Oligocene. Such a change in the ocean-climate system is expected to alter the pelagic ecosystem through elevated rates of extinction and increased biogeographic provincialism. A well documented, but poorly understood, example of this provincialism is the recurrence of unusual chalks composed of the nannofossil genus Braarudosphaera across the subtropical South Atlantic Ocean. Here we present preliminary findings from a study of the paleoceanographic conditions that fostered these Braarudosphaera "blooms" at Deep Sea Drilling Site 516 (Rio Grande Rise, southwestern Atlantic). Within the early Oligocene stratigraphy at this site, there are four chalky (recrystallized) layers in which braarudosphaerids compose ~70% of the nannofossil assemblages. Astronomical tuning was performed on conventional benthic foraminiferal δ18O and δ13C records encompassing the four layers to determine the timing of their recurrence. A strong astronomical rhythm is preserved with the blooms occurring during nodes in the theoretical obliquity solution. In addition, planktic foraminiferal stable isotope (δ18O, δ13C) records were generated for the study section using both secondary ion mass spectrometry (SIMS) and conventional gas-source isotope ratio mass spectrometry (IRMS). The SIMS-based δ13C record for the thermocline-dwelling genus Catapsydrax registers substantial (~1.5‰) decreases during the blooms, signaling pulsed increases in the upwelling of 13C-depleted waters. By contrast, the IRMS-based δ13C record for this same genus show no appreciable change in hydrographic conditions during the blooms. We attribute the invariant nature of the IRMS-based δ13C record to the smoothing effects of diagenesis. These results demonstrate how marine plankton respond to changing oceanographic conditions driven by astronomical forcing of ice-sheet dynamics.

Spectacular Oscillations in Plant Isoprene Emission under Transient Conditions Explain the Enigmatic CO2 Response1

PubMed Central

2016-01-01

Plant isoprene emissions respond to light and temperature similarly to photosynthesis, but CO2 dependencies of isoprene emission and photosynthesis are profoundly different, with photosynthesis increasing and isoprene emission decreasing with increasing CO2 concentration due to reasons not yet understood. We studied isoprene emission, net assimilation rate, and chlorophyll fluorescence under different CO2 and O2 concentrations in the strong isoprene emitter hybrid aspen (Populus tremula × Populus tremuloides), and used rapid changes in ambient CO2 or O2 concentrations or light level to induce oscillations. As isoprene-emitting species support very high steady-state chloroplastic pool sizes of the primary isoprene substrate, dimethylallyl diphosphate (DMADP), which can mask the effects of oscillatory dynamics on isoprene emission, the size of the DMADP pool was experimentally reduced by either partial inhibition of isoprenoid synthesis pathway by fosmidomycin-feeding or by changes in ambient gas concentrations leading to DMADP pool depletion in intact leaves. In feedback-limited conditions observed at low O2 and/or high CO2 concentration under which the rate of photosynthesis is governed by the limited rate of ATP and NADPH formation due to low chloroplastic phosphate levels, oscillations in photosynthesis and isoprene emission were repeatedly induced by rapid environmental modifications in both partly fosmidomycin-inhibited leaves and in intact leaves with in vivo reduced DMADP pools. The oscillations in net assimilation rate and isoprene emission in feedback-inhibited leaves were in the same phase, and relative changes in the pools of photosynthetic metabolites and DMADP estimated by in vivo kinetic methods were directly proportional through all oscillations induced by different environmental perturbations. We conclude that the oscillations in isoprene emission provide direct experimental evidence demonstrating that the response of isoprene emission to changes in ambient gas concentrations is controlled by the chloroplastic reductant supply. PMID:27770061

Infill of tunnel valleys associated with landward-flowing ice sheets: The missing Middle Pleistocene record of the NW European rivers?

NASA Astrophysics Data System (ADS)

Moreau, Julien; Huuse, Mads

2014-01-01

The southern termination of the Middle and Late Pleistocene Scandinavian ice sheets was repeatedly located in the southern North Sea (sNS) and adjacent, north-sloping land areas. Giant meltwater-excavated valleys (tunnel valleys) formed at the southern termination of the ice sheets and contain a hitherto enigmatic succession of northward prograding clinoforms, comprising 1000s km3 of sediment. This study analyses 3D seismic data, covering the entire sNS, and demonstrates for the first time that the formation of these tunnel valleys was separate from their infill. The infill constitutes the postglacial record of the NW European river deltas, which had so far been considered missing.

Tako-tsubo-like syndrome, a case report.

PubMed

Patanè, Salvatore; Marte, Filippo

2008-02-29

Tako-tsubo-like (Japanese word for octopus-catcher) left ventricular dysfunction is an enigmatic cardiomyopathy. Typically, the patients have a history of recent stressful incidents immediately preceding onset of mild to moderate chest pain, have ST-segment elevation in leads V3 through V6, ECG changes that typically demonstrate diffuse T-wave inversions and abnormal QS-wave development, discrete wall motion abnormalities involving the lower anterior wall and apex on echocardiography or left ventriculography, and limited myocardial enzyme release without evidence for hemodynamically significant coronary arterial stenoses by angiography. We describe a case of a Tako-tsubo-like left ventricular dysfunction in a 72-year-old female Italian woman.

Distribution and Orientation of Alluvial Fans in Martian Craters

NASA Technical Reports Server (NTRS)

Kraal, E. R.; Moore, J. M.; Howard, A. D.; Asphaug, E. I.

2005-01-01

We present the results of the complete survey of Martian alluvial fans from 0-30 S, initiated by Moore and Howard. Nineteen impact craters contain alluvial fans. They are regionally grouped into three distinct areas. We present our initial results regarding their distribution and orientation in order to understand what controls their formation. Since alluvial fans are formed by water transport of sediment, these features record wetter episodes of Martian climate. In addition, their enigmatic distribution (in regional groups and in some craters, but not similar adjacent ones) needs to be understood, to see how regional geology, topographic characteristics, and/or climate influence their formation and distribution.

Frog decline, frog malformations, and a comparison of frog and human health.

PubMed

Cohen, M M

2001-11-22

The decline in frog populations and the increase in the frequency of frog malformations are discussed. Topics considered for analysis include chytridiomycosis, retinoids, UV-B radiation, chemical contaminants, environmental threats, introduced invasive species and predation, unsustainable use, and enigmatic decline. Care must be taken to distinguish between hypotheses, laboratory experiments, and the findings in feral frog populations. Clearly, the causes of population decline and malformations are heterogeneous. The subject of frogs and humans is addressed under three subheadings: the importance of frogs to human societies, medical implications of frog studies, and a comparison of frog and human disease factors. Copyright 2001 Wiley-Liss, Inc.

GRACE Gravity Data Target Possible Mega-impact in North Central Wilkes Land, Antarctica

NASA Technical Reports Server (NTRS)

vonFrese, Ralph R. B.; Wells, Stuart B.; Potts. Laramie V.; Gaya-Pique, Luis R.; Golynsky, Alexander V.; Hernandez, Orlando; Kim, Jeong Woo; Kim, Hyung Rae; Hwang, Jong Sun; Taylor, Patrick T.

2005-01-01

A prominent positive GRACE satellite-measured free-air gravity anomaly over regionally depressed subglacial topography may identify a mascon centered on (70 deg S, 120 deg E) between the Gamburtsev and Transantarctic Mountains of East Antarctica. Being more than twice the size of the Chicxulub crater, the inferred Wilkes Land impact crater is a strong candidate for a Gondwana source of the greatest extinction of life at the end of the Permian. Its ring structure intersects the coastline and thus may have strongly influenced the Cenozoic rifting of East Antarctica from Australia that resulted in the enigmatic lack of crustal thinning on the conjugate Australian block.

Toward understanding early Earth evolution: Prescription for approach from terrestrial noble gas and light element records in lunar soils

PubMed Central

Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.

2008-01-01

Because of the almost total lack of geological record on the Earth's surface before 4 billion years ago, the history of the Earth during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light elements such as He, N, O, Ne, and Ar would shed a new light on this dark age in the Earth's history and resolve three of the most fundamental questions in earth science: the onset time of the geomagnetic field, the appearance of an oxygen atmosphere, and the secular variation of an Earth–Moon dynamical system. PMID:19001263

Nanostructured Drugs Embedded into a Polymeric Matrix: Vinpocetine/PVP Hybrids Investigated by Debye Function Analysis.

PubMed

Hasa, Dritan; Giacobbe, Carlotta; Perissutti, Beatrice; Voinovich, Dario; Grassi, Mario; Cervellino, Antonio; Masciocchi, Norberto; Guagliardi, Antonietta

2016-09-06

Microcrystalline vinpocetine, coground with cross-linked polyvinylpyrrolidone, affords hybrids containing nanosized drug nanocrystals, the size and size distributions of which depend on milling times and drug-to-polymer weight ratios. Using an innovative approach to microstructural characterization, we analyzed wide-angle X-ray total scattering data by the Debye function analysis and demonstrated the possibility to characterize pharmaceutical solid dispersions obtaining a reliable quantitative view of the physicochemical status of the drug dispersed in an amorphous carrier. The microstructural properties derived therefrom have been successfully employed in reconciling the enigmatic difference in behavior between in vitro and in vivo solubility tests performed on nanosized vinpocetine embedded in a polymeric matrix.

Porphyritic Olivine-Pyroxene Clast in Kaidun: First Discovery of an Ordinary Chondrite Clast?

NASA Technical Reports Server (NTRS)

Mikouchi, T.; Makishima, J.; Koizumi, E.; Zolensky, M. E.

2005-01-01

Kaidun is an enigmatic meteorite showing a micro-brecciated texture composed of variable kinds of lithic clasts and mineral fragments. The constituent components range from primitive chondritic materials to differentiated achondritic materials, and thus believed to have originated from a large parent body accumulating materials from many different bodies in the asteroid belt. One of the interesting observations is that no ordinary chondrite component has been found yet, although C and E chondrites components are abundant. In this abstract, we report mineralogy of the clast (Kaidun #15415- 01.3.13a) showing a porphyritic olivine-pyroxene chondrule-like texture similar to those found in unequilibrated ordinary chondrites.

The Hermetic Frontispiece: Contextualising John Dee's Hieroglyphic Monad.

PubMed

Forshaw, Peter J

2017-05-01

This essay examines the elaborate title pages of some of alchemist, astrologer, and bibliophile John Dee's publications with a focus on the two best known works that feature his famous Hieroglyphic Monad, the Propaedeumata Aphoristica (1558) and Monas Hieroglyphica (1564). The aim is to cast light on its context, identify sources for some textual influences in the works, unpack the visual symbolism in the two "monadic" title pages in relation to the two complementary sciences of "superior" and "inferior" astronomy, speculate on some of the more enigmatic details, and conclude with a brief discussion of a possible astrological significance to the dates of composition of the Monas Hieroglyphica.

Bluetooth: The invisible connector. Short-range wireless technology for the contemporary orthodontic practice.

PubMed

Mupparapu, Muralidhar

2007-06-01

Although it sounds like a nonvital tooth, Bluetooth is actually one of technology's hottest trends. It is an industrial specification for wireless personal area networks, but for a busy orthodontic practice, it translates to freedom from cables and cords. Despite its enigmatic name, Bluetooth-based devices and the wireless technology that these gadgets work with are here to stay. They promise to make life easier for the electronic-device users of all stripes, and orthodontists are no exception. The purpose of this article is to orient orthodontists, office staff, and auxiliary personnel to this universal wireless technology that is slowly becoming an integral part of every office.

Synaptophysin regulates the kinetics of synaptic vesicle endocytosis in central neurons

PubMed Central

Kwon, Sung E.; Chapman, Edwin R.

2011-01-01

Summary Despite being the most abundant synaptic vesicle membrane protein, the function of synaptophysin remains enigmatic. For example, synaptic transmission was reported to be completely normal in synaptophysin knockout mice; however, direct experiments to monitor the synaptic vesicle cycle have not been carried out. Here, using optical imaging and electrophysiological experiments, we demonstrate that synaptophysin is required for kinetically efficient endocytosis of synaptic vesicles in cultured hippocampal neurons. Truncation analysis revealed that distinct structural elements of synaptophysin differentially regulate vesicle retrieval during and after stimulation. Thus, synaptophysin regulates at least two phases of endocytosis to ensure vesicle availability during and after sustained neuronal activity. PMID:21658579

An exhumed Late Paleozoic canyon in the rocky mountains

USGS Publications Warehouse

Soreghan, G.S.; Sweet, D.E.; Marra, K.R.; Eble, C.F.; Soreghan, M.J.; Elmore, R.D.; Kaplan, S.A.; Blum, M.D.

2007-01-01

Landscapes are thought to be youthful, particularly those of active orogenic belts. Unaweep Canyon in the Colorado Rocky Mountains, a large gorge drained by two opposite-flowing creeks, is an exception. Its origin has long been enigmatic, but new data indicate that it is an exhumed late Paleozoic landform. Its survival within a region of profound late Paleozoic orogenesis demands a reassessment of tectonic models for the Ancestral Rocky Mountains, and its form and genesis have significant implications for understanding late Paleozoic equatorial climate. This discovery highlights the utility of paleogeomorphology as a tectonic and climatic indicator. ?? 2007 by The University of Chicago. All rights reserved.

A guide to the clinical management of attrition.

PubMed

Rees, J S; Somi, S

2018-03-09

Attrition is an enigmatic condition often found in older individuals and often as a result of bruxism which can take place as a result of either day bruxism, night bruxism or both. Various studies and systemic reviews clearly shown that tooth wear is an age-related phenomena and the last Adult Dental Health Survey showed that 15% of participants showed moderate wear and 3% severe wear with 80% of patients over 50 years of age showing signs of wear. This review examines current theories around the aetiological factors contributing to attrition together with the clinical management of attrition focusing on minimal intervention where possible.

Deep-focus earthquakes and recycling of water into the earth's mantle

NASA Technical Reports Server (NTRS)

Meade, Charles; Jeanloz, Raymond

1991-01-01

For more than 50 years, observations of earthquakes to depths of 100 to 650 kilometers inside earth have been enigmatic: at these depths, rocks are expected to deform by ductile flow rather than brittle fracturing or frictional sliding on fault surfaces. Laboratory experiments and detailed calculations of the pressures and temperatures in seismically active subduction zones indicate that this deep-focus seismicity could originate from dehydration and high-pressure structural instabilities occurring in the hydrated part of the lithosphere that sinks into the upper mantle. Thus, seismologists may be mapping the recirculation of water from the oceans back into the deep interior of the planet.

Ancestor–descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata

PubMed Central

Tsai, Cheng-Hsiu; Fordyce, R. Ewan

2015-01-01

Ancestor–descendant relationships (ADRs), involving descent with modification, are the fundamental concept in evolution, but are usually difficult to recognize. We examined the cladistic relationship between the only reported fossil pygmy right whale, †Miocaperea pulchra, and its sole living relative, the enigmatic pygmy right whale Caperea marginata, the latter represented by both adult and juvenile specimens. †Miocaperea is phylogenetically bracketed between juvenile and adult Caperea marginata in morphologically based analyses, thus suggesting a possible ADR—the first so far identified within baleen whales (Cetacea: Mysticeti). The †Miocaperea–Caperea lineage may show long-term morphological stasis and, in turn, punctuated equilibrium. PMID:25589485

Water and hydrogen are immiscible in Earth's mantle.

PubMed

Bali, Enikő; Audétat, Andreas; Keppler, Hans

2013-03-14

In the deep, chemically reducing parts of Earth's mantle, hydrous fluids contain significant amounts of molecular hydrogen (H2). Thermodynamic models of fluids in Earth's mantle so far have always assumed that molecular hydrogen and water are completely miscible. Here we show experimental evidence that water and hydrogen can coexist as two separate, immiscible phases. Immiscibility between water and hydrogen may be the cause of the formation of enigmatic, ultra-reducing domains in the mantle that contain moissanite (SiC) and other phases indicative of extremely reducing conditions. Moreover, the immiscibility between water and hydrogen may provide a mechanism for the rapid oxidation of Earth's upper mantle immediately following core formation.

Phylogenetic position of the genus Perkinsus (Protista, Apicomplexa) based on small subunit ribosomal RNA.

PubMed

Goggin, C L; Barker, S C

1993-07-01

Parasites of the genus Perkinsus destroy marine molluscs worldwide. Their phylogenetic position within the kingdom Protista is controversial. Nucleotide sequence data (1792 bp) from the small subunit rRNA gene of Perkinsus sp. from Anadara trapezia (Mollusca: Bivalvia) from Moreton Bay, Queensland, was used to examine the phylogenetic affinities of this enigmatic genus. These data were aligned with nucleotide sequences from 6 apicomplexans, 3 ciliates, 3 flagellates, a dinoflagellate, 3 fungi, maize and human. Phylogenetic trees were constructed after analysis with maximum parsimony and distance matrix methods. Our analyses indicate that Perkinsus is phylogenetically closer to dinoflagellates and to coccidean and piroplasm apicomplexans than to fungi or flagellates.

Genocide in Bosnia: the case of Dr. Radovan Karadzic.

PubMed

Dekleva, K B; Post, J M

1997-01-01

From 1992 to 1995 the Republic of Bosnia-Herzegovina experienced a war of genocidal proportions between the Bosnian Serbs, the Bosnian Croats, and the Bosnian Muslims. The international Criminal Tribunal for the Former Yugoslavia has indicted Dr. Radovan Karadzic--former President of the Bosnian Serb Republic, psychiatrist, and poet--as a suspected war criminal for his role in war crimes, crimes against humanity, and genocide. Karadzic remains enigmatic and poorly understood. Psychological profiling highlights in Karadzic's case the complex coalescence of the psychology of a genocide perpetrator with that of a charismatic narcissistic political leader. Such a profile may possess usefulness in forensic psychiatric investigations and legal proceedings.

Identifying Unidentified Fermi-LAT Objects (UFOs) at High-Latitude

NASA Astrophysics Data System (ADS)

Cheung, Chi Teddy

2009-09-01

We propose a Chandra study of 8 high Galactic latitude gamma-ray sources in the Fermi-LAT bright source list. These sources are currently unidentified, i.e., they are not clearly associated with established classes of gamma-ray emitters like blazars and pulsars. The proposed observations will determine the basic properties (fluxes, positions, hardness ratio/spectra) of all X-ray sources down to a 0.3-10 keV flux limit of 1.5e-14 erg/cm2/s within the Fermi-LAT localization circles. This will enable further follow-up at other wavelengths, with the ultimate goal to reveal the nature of these enigmatic gamma-ray sources.

Star motion around rotating black hole in the Galactic Center in real time

NASA Astrophysics Data System (ADS)

Dokuchaev, Vyacheslav; Nazarova, Natalia

2017-12-01

The Event Horizon Telescope team intends by the 2020 to resolve the shadow of supermassive black hole SgrA* in the Galactic Center. It would be the first attempt for direct identification of the enigmatic black hole. In other words, it would be the first experimental verification of the General Relativity in the strong field limit. There is a chance to find a star moving on the relativistic orbit close to this black hole. We present the animated numerical model of the gravitational lensing of a star (or any other lighting probe), moving around rotating Kerr black hole in the Galactic Center and viewed by the distant observer.

Anatomy, feeding ecology, and ontogeny of a transitional baleen whale: a new genus and species of Eomysticetidae (Mammalia: Cetacea) from the Oligocene of New Zealand

PubMed Central

Fordyce, R. Ewan

2015-01-01

The Eocene history of cetacean evolution is now represented by the expansive fossil record of archaeocetes elucidating major morphofunctional shifts relating to the land to sea transition, but the change from archaeocetes to modern cetaceans is poorly established. New fossil material of the recently recognized family Eomysticetidae from the upper Oligocene Otekaike Limestone includes a new genus and species, Waharoa ruwhenua, represented by skulls and partial skeletons of an adult, juvenile, and a smaller juvenile. Ontogenetic status is confirmed by osteohistology of ribs. Waharoa ruwhenua is characterized by an elongate and narrow rostrum which retains vestigial alveoli and alveolar grooves. Palatal foramina and sulci are present only on the posterior half of the palate. The nasals are elongate, and the bony nares are positioned far anteriorly. Enormous temporal fossae are present adjacent to an elongate and narrow intertemporal region with a sharp sagittal crest. The earbones are characterized by retaining inner and outer posterior pedicles, lacking fused posterior processes, and retaining a separate accessory ossicle. Phylogenetic analysis supports inclusion of Waharoa ruwhenua within a monophyletic Eomysticetidae as the earliest diverging clade of toothless mysticetes. This eomysticetid clade also included Eomysticetus whitmorei, Micromysticetus rothauseni, Tohoraata raekohao, Tokarahia kauaeroa, Tokarahia lophocephalus, and Yamatocetus canaliculatus. Detailed study of ontogenetic change demonstrates postnatal elaboration of the sagittal and nuchal crests, elongation of the intertemporal region, inflation of the zygomatic processes, and an extreme proportional increase in rostral length. Tympanic bullae are nearly full sized during early postnatal ontogeny indicating precocial development of auditory structures, but do increase slightly in size. Positive allometry of the rostrum suggests an ontogenetic change in feeding ecology, from neonatal suckling to a more

Long-chain polyunsaturated fatty acid biosynthesis in the euryhaline herbivorous teleost Scatophagus argus: Functional characterization, tissue expression and nutritional regulation of two fatty acyl elongases.

PubMed

Xie, Dizhi; Chen, Fang; Lin, Siyuan; You, Cuihong; Wang, Shuqi; Zhang, Qinghao; Monroig, Óscar; Tocher, Douglas R; Li, Yuanyou

2016-08-01

Both the spotted scat Scatophagus argus and rabbitfish Siganus canaliculatus belong to the few cultured herbivorous marine teleost, however, their fatty acyl desaturase (Fad) system involved in long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis is different. The S. argus has a △6 Fad, while the rabbitfish has △4 and △6/△5 Fads, which were the first report in vertebrate and marine teleost, respectively. In order to compare the characteristics of elongases of very long-chain fatty acids (Elovl) between them, two Elovl cDNAs were cloned from S. argus in the present study. One has 885bp of open read fragment (ORF) encoding a protein with 294 amino acid (aa) showing Elovl5 activity functionally characterized by heterologous expression in yeast, which was primarily active for the elongation of C18 and C20 PUFAs. The other has 915bp of ORF coding for a 305 aa protein showing Elovl4 activity, which was more efficient in the elongation of C20 and C22 PUFAs. Tissue distribution analyses by RT-PCR showed that elovl5 was highly expressed in the liver compared to other tissues determined, whereas elovl4 transcripts were only detected in the eye. The expression of elovl5 and elovl4 were significantly affected by dietary fatty acid composition, with highest expression of mRNA in the liver and eye of fish fed a diet with an 18:3n-3/18:2n-6 ratio of 1.7:1. These results indicated that the S. argus has a similar Elovl system in the LC-PUFA biosynthetic pathway to that of rabbitfish although their Fad system was different, suggesting that the diversification of fish LC-PUFA biosynthesis specificities is more associated with its Fad system. These new insights expand our knowledge and understanding of the molecular basis and regulation of LC-PUFA biosynthesis in fish. Copyright © 2016 Elsevier Inc. All rights reserved.

Anatomy, feeding ecology, and ontogeny of a transitional baleen whale: a new genus and species of Eomysticetidae (Mammalia: Cetacea) from the Oligocene of New Zealand.

PubMed

Boessenecker, Robert W; Fordyce, R Ewan

2015-01-01

The Eocene history of cetacean evolution is now represented by the expansive fossil record of archaeocetes elucidating major morphofunctional shifts relating to the land to sea transition, but the change from archaeocetes to modern cetaceans is poorly established. New fossil material of the recently recognized family Eomysticetidae from the upper Oligocene Otekaike Limestone includes a new genus and species, Waharoa ruwhenua, represented by skulls and partial skeletons of an adult, juvenile, and a smaller juvenile. Ontogenetic status is confirmed by osteohistology of ribs. Waharoa ruwhenua is characterized by an elongate and narrow rostrum which retains vestigial alveoli and alveolar grooves. Palatal foramina and sulci are present only on the posterior half of the palate. The nasals are elongate, and the bony nares are positioned far anteriorly. Enormous temporal fossae are present adjacent to an elongate and narrow intertemporal region with a sharp sagittal crest. The earbones are characterized by retaining inner and outer posterior pedicles, lacking fused posterior processes, and retaining a separate accessory ossicle. Phylogenetic analysis supports inclusion of Waharoa ruwhenua within a monophyletic Eomysticetidae as the earliest diverging clade of toothless mysticetes. This eomysticetid clade also included Eomysticetus whitmorei, Micromysticetus rothauseni, Tohoraata raekohao, Tokarahia kauaeroa, Tokarahia lophocephalus, and Yamatocetus canaliculatus. Detailed study of ontogenetic change demonstrates postnatal elaboration of the sagittal and nuchal crests, elongation of the intertemporal region, inflation of the zygomatic processes, and an extreme proportional increase in rostral length. Tympanic bullae are nearly full sized during early postnatal ontogeny indicating precocial development of auditory structures, but do increase slightly in size. Positive allometry of the rostrum suggests an ontogenetic change in feeding ecology, from neonatal suckling to a more

Reactions of Standing Bipeds on Moving Platforms to Keep Their Balance May Increase the Amplitude of Oscillations of Platforms Satisfying Hooke's Law.

PubMed

Goldsztein, Guillermo H

2016-01-01

Consider a person standing on a platform that oscillates laterally, i.e. to the right and left of the person. Assume the platform satisfies Hooke's law. As the platform moves, the person reacts and moves its body attempting to keep its balance. We develop a simple model to study this phenomenon and show that the person, while attempting to keep its balance, may do positive work on the platform and increase the amplitude of its oscillations. The studies in this article are motivated by the oscillations in pedestrian bridges that are sometimes observed when large crowds cross them.

Evolutionary history of enigmatic bears in the Tibetan Plateau–Himalaya region and the identity of the yeti

PubMed Central

Lan, Tianying; Gill, Stephanie; Bellemain, Eva; Bischof, Richard; Nawaz, Muhammad Ali

2017-01-01

Although anecdotally associated with local bears (Ursus arctos and U. thibetanus), the exact identity of ‘hominid’-like creatures important to folklore and mythology in the Tibetan Plateau–Himalaya region is still surrounded by mystery. Recently, two purported yeti samples from the Himalayas showed genetic affinity with an ancient polar bear, suggesting they may be from previously unrecognized, possibly hybrid, bear species, but this preliminary finding has been under question. We conducted a comprehensive genetic survey of field-collected and museum specimens to explore their identity and ultimately infer the evolutionary history of bears in the region. Phylogenetic analyses of mitochondrial DNA sequences determined clade affinities of the purported yeti samples in this study, strongly supporting the biological basis of the yeti legend to be local, extant bears. Complete mitochondrial genomes were assembled for Himalayan brown bear (U. a. isabellinus) and black bear (U. t. laniger) for the first time. Our results demonstrate that the Himalayan brown bear is one of the first-branching clades within the brown bear lineage, while Tibetan brown bears diverged much later. The estimated times of divergence of the Tibetan Plateau and Himalayan bear lineages overlap with Middle to Late Pleistocene glaciation events, suggesting that extant bears in the region are likely descendants of populations that survived in local refugia during the Pleistocene glaciations. PMID:29187630

Comparative analyses imply that the enigmatic sigma factor 54 is a central controller of the bacterial exterior

PubMed Central

2011-01-01

Background Sigma-54 is a central regulator in many pathogenic bacteria and has been linked to a multitude of cellular processes like nitrogen assimilation and important functional traits such as motility, virulence, and biofilm formation. Until now it has remained obscure whether these phenomena and the control by Sigma-54 share an underlying theme. Results We have uncovered the commonality by performing a range of comparative genome analyses. A) The presence of Sigma-54 and its associated activators was determined for all sequenced prokaryotes. We observed a phylum-dependent distribution that is suggestive of an evolutionary relationship between Sigma-54 and lipopolysaccharide and flagellar biosynthesis. B) All Sigma-54 activators were identified and annotated. The relation with phosphotransfer-mediated signaling (TCS and PTS) and the transport and assimilation of carboxylates and nitrogen containing metabolites was substantiated. C) The function annotations, that were represented within the genomic context of all genes encoding Sigma-54, its activators and its promoters, were analyzed for intra-phylum representation and inter-phylum conservation. Promoters were localized using a straightforward scoring strategy that was formulated to identify similar motifs. We found clear highly-represented and conserved genetic associations with genes that concern the transport and biosynthesis of the metabolic intermediates of exopolysaccharides, flagella, lipids, lipopolysaccharides, lipoproteins and peptidoglycan. Conclusion Our analyses directly implicate Sigma-54 as a central player in the control over the processes that involve the physical interaction of an organism with its environment like in the colonization of a host (virulence) or the formation of biofilm. PMID:21806785

Unraveling of Enigmatic Hearing-Impaired GJB2 Single Heterozygotes by Massive Parallel Sequencing: DFNB1 or Not?

PubMed Central

Kim, So Young; Kim, Ah Reum; Kim, Nayoung K. D.; Lee, Chung; Kim, Min Young; Jeon, Eun-Hee; Park, Woong-Yang; Choi, Byung Yoon

2016-01-01

Abstract The molecular etiology of nonsyndromic sensorineural hearing loss (SNHL) in subjects with only one detectable autosomal recessive GJB2 mutation is unclear. Here, we report GJB2 single heterozygotes with various final genetic diagnoses and suggest appropriate diagnostic strategies. A total of 160 subjects with SNHL without phenotypic markers were screened for GJB2 mutations. Single-nucleotide variants or structural variations within the DFNB1 locus or in other deafness genes were examined by Sanger sequencing, breakpoint PCR, and targeted exome sequencing (TES) of 129 deafness genes. We identified 27 subjects with two mutations and 10 subjects with only one detectable mutation in GJB2. The detection rate of the single GJB2 mutation among the 160 SNHL subjects in the present study (6.25%) was higher than 2.58% in normal hearing controls in Korean. The DFNB1 was clearly excluded as a molecular etiology in four (40%) subjects: other recessive deafness genes (N = 3) accounted for SNHL and the causative gene for the other non-DFNB1 subject (N = 1) was not identified. The etiology of additional two subjects was potentially explained by digenic etiology (N = 2) of GJB2 with MITF and GJB3, respectively. The contribution of the single GJB2 mutation in the four remaining subjects is unclear. Comprehensive diagnostic testing including TES is prerequisite for understanding GJB2 single heterozygotes. PMID:27057829

On the identity and taxonomic status of the enigmatic mantid Thespoides bolivari Chopard, 1916 (Mantodea: Mantidae, Angelinae).

PubMed

Rivera, Julio

2014-05-21

Chopard (1916) published a brief paper in which he cited and described a number of praying mantis species from the neotropics. The specimens he studied belonged to the prominent Spanish Entomologist Ignacio Bolívar y Urrutia (1850-1944), whose collection is now housed at the Museo Nacional de Ciencias Naturales in Madrid (MNCN), Spain (Izquierdo et al. 1997). In this publication Chopard described Thespoides bolivari Chopard, 1916 as a new genus and species, based on a single male obtained by French coleopterist René Oberthür in Cauca, Colombia. According to Chopard (1916) the specimen was remarkable for having, among other features, an abdomen that is markedly shorter than the rest of its body-certainly an unusual morphological trait among the Mantodea. Chopard assigned Thespoides to the Miopteryginae (Thespidae), but it was later reassigned (together with Angela Serville, 1839 as the "Angelae group") to the subfamily Schizocephalinae (Mantidae) by Giglio-Tos (1927). Current classifications consider the Angelinae to comprise a distinct subfamily of the Mantidae, with Thespoides and Angela as the only representatives of this subfamily with a Neotropical distribution (e.g. Ehrmann 2002).

The Enigmatic Local Hubble Flow: Probing the Nearby Peculiar Velocity Field with Consistent Distances to Neighboring Galaxies.

NASA Astrophysics Data System (ADS)

Mendez, B.; Davis, M.; Newman, J.; Madore, B. F.; Freedman, W. L.; Moustakas, J.

2002-12-01

The properties of the velocity field in the local volume (cz < 550 km s-1) have been difficult to constrain due to a lack of a consistent set of galaxy distances. The sparse observations available to date suggest a remarkably quiet flow, with little deviation from a pure Hubble law. However, velocity field models based on the distribution of galaxies in the 1.2 Jy IRAS redshift survey, predict a quadrupolar flow pattern locally with strong infall at the poles of the local Supergalactic plane. In an attempt to resolve this discrepency, we probe the local velocity field and begin to establish a consistent set of galactic distances. We have obtained images of nearby galaxies in I, V, and B bands from the W.M. Keck Observatory and in F814W and F555W filters from the Hubble Space Telescope. Where these galaxies are well resolved into stars we can use the Tip of the Red Giant Branch (TRGB) as a distance indicator. Using a maximum likelihood analysis to quantitatively measure the I magnitude of the TRGB we determine precise distances to several nearby galaxies. We supplement that dataset with published distances to local galaxies measured using Cepheids, Surface Brightness Fluctuations, and the TRGB. With these data we find that the amplitude of the local flow is roughly half that expected in linear theory and N-body simulations; thus the enigma of cold local flows persists. This work was supported in part by NASA through a grant from the Space Telescope Science Institute and a Predoctoral Fellowship for Minorities from the Ford Foundation.

The first occurrence of the enigmatic archosauriform Crosbysaurus Heckert 2004 from the Chinle Formation of southern Utah.

PubMed

Gay, Robert J; Aude, Isabella St

2015-01-01

Originally identified as an ornithischian dinosaur, Crosbysaurus harrisae has been found in New Mexico, Arizona, and its type locality in Texas, as well as in North Carolina. The genus has been reassessed by other workers in light of reinterpretations about the postcrania of another putative Triassic ornithischian, Revueltosaurus. The understanding of Triassic dental faunas has become more complicated by the extreme convergence between pseudosuchian archosaurs and ornithischian dinosaur dental morphologies. We report here on a new specimen of Crosbysaurus (MNA V10666) from the Chinle Formation at Comb Ridge in southeastern Utah. This new specimen is assigned to Crosbysaurus sp. on the basis of the unique compound posterior denticles, labiolingual width, and curvature. While MNA V10666 does not help resolve the affinities of Crosbysaurus, it does represent the extension of the geographic range of this taxon for approximately 250 kilometers. This is the first record of the genus Crosbysaurus in Utah and as such it represents the northernmost known record of this taxon. This indicates that Crosbysaurus was not limited to the southern area of the Chinle/Dockum deposition but instead was widespread across the Late Triassic paleoriver systems of western Pangea. The reported specimen was found in close association with a typical Late Triassic Chinle fauna, including phytosaurs, metoposaurs, and dinosauromorphs.

An enigmatic fossil fungus from the 410 Ma Rhynie chert that resembles Macrochytrium (Chytridiomycota) and Blastocladiella (Blastocladiomycota).

PubMed

Krings, Michael; Taylor, Thomas N; Martin, Helmut

2016-01-01

Litter layers in the Lower Devonian (~ 410 Ma) Rhynie chert were inhabited by a wide variety of saprotrophic fungi, however, only a few of these organisms have been described formally. A new microfungus, Trewinomyces annulifer gen. et sp. nov., occurs as tufts on decaying land plant axes from the Rhynie chert. The fungus consists of an intramatrical rhizoidal system and an erect extramatrical hypha (stalk) that bears a single, terminal sporangium. One or two successive rings often are present in the stalk immediately below the sporangium base. Overall morphology of T. annulifer resembles the extant genera Macrochytrium (Chytridiomycota) and Blastocladiella (Blastocladiomycota). However, the rhizoids are septate or pseudoseptate, a feature not known in extant zoosporic fungi, and thus render the systematic affinities of T. annulifer unresolved. Trewinomyces annulifer offers a rare view of the morphology of a distinctive Early Devonian saprotrophic microfungus. © 2016 by The Mycological Society of America.

Gene expression analysis of aquatic angiosperms podostemaceae to gain insight into the evolution of their enigmatic morphology.

PubMed

Koi, Satoshi; Katayama, Natsu

2013-01-01

Podostemaceae is a family of aquatic angiosperms growing submerged on rocks in fast-flowing water and called moss-like or alga-like riverweeds. It evolved remarkable innovations to adapt to such an extreme environment, one of which is reduced shoots borne on roots adhering to rock surface. Recent observations revealed that the basal subfamily Tristichoideae, like most other angiosperms, has typical shoot apical meristems (SAMs). In species of the subfamily Podostemoideae, however, shoot apical meristems (SAMs) are not formed during development and new leaves arise from the meristematic basal region of preexisting leaves. The genetic basis of this shoot organogenesis process, e.g., the expression patterns of genes homologous to transcription factors regulating shoot development, is essential to better understand the evolution of Podostemaceae. A gene expression analysis found that the SAM-less Podostemoideae leaf has mixed identity of SAM and leaf, and provided insight into the evolution of the shoot in Podostemaceae.

Biosystematics and Conservation: A Case Study with Two Enigmatic and Uncommon Species of Crassula from New Zealand

PubMed Central

De Lange, P. J.; Heenan, P. B.; Keeling, D. J.; Murray, B. G.; Smissen, R.; Sykes, W. R.

2008-01-01

Background and Aims Crassula hunua and C. ruamahanga have been taxonomically controversial. Here their distinctiveness is assessed so that their taxonomic and conservation status can be clarified. Methods Populations of these two species were analysed using morphological, chromosomal and DNA sequence data. Key Results It proved impossible to differentiate between these two species using 12 key morphological characters. Populations were found to be chromosomally variable with 11 different chromosome numbers ranging from 2n = 42 to 2n = 100. Meiotic behaviour and levels of pollen stainability were both variable. Phylogenetic analyses showed that differences exist in both nuclear and plastid DNA sequences between individual plants, sometimes from the same population. Conclusions The results suggest that these plants are a species complex that has evolved through interspecific hybridization and polyploidy. Their high levels of chromosomal and DNA sequence variation present a problem for their conservation. PMID:18055560

Orbital solution leading to an acceptable interpretation for the enigmatic gamma-ray binary HESS J0632+057

NASA Astrophysics Data System (ADS)

Moritani, Yuki; Kawano, Takafumi; Chimasu, Sho; Kawachi, Akiko; Takahashi, Hiromitsu; Takata, Jumpei; Carciofi, Alex C.

2018-05-01

High-dispersion spectroscopic monitoring of HESS J0632+057 has been carried out over four orbital cycles in order to search for orbital modulation, covering the entire orbital phase. We have measured the radial velocity of the Hα emission line with the method introduced by Shafter, Szkody, and Thorstensen (1986, ApJ, 308, 765), which has been successfully applied to some Be stars. The velocity is seen to increase much earlier than expected for the orbital period of 315 d, and much more steeply than expected at around "apastron." The period of the Hα modulation is found to be 308^{+26}_{-23} d. We have also analyzed Swift/XRT data from 2009 to 2015 to study the orbital modulation, selecting the data with good statistics (≥30 counts). With additional two-year data to the previous works, the orbital period has been updated to 313^{+11}_{-8} d, which is consistent with the previous X-ray periods and the spectroscopic one. Previous XMM-Newton and Chandra observations prefer a period of 313 d. With the new period, assuming that Hα velocities accurately trace the motion of the Be star, we have derived a new set of orbital parameters. In the new orbit, which is less eccentric (e ≃ 0.6), two outbursts occur: after apastron and just after periastron. Also, the column density in bright phase (4.7^{+0.9}_{-08}× 10^{21} cm^{-2}) is higher than in faint phase (2.2 ± 0.5 × 1021 cm-2). These facts suggest that outbursts occur when the compact object passes nearby/through the Be disk. The mass function implies that the mass of the compact object is less than 2.5 M⊙, assuming that the mass of the Be star is 13.2-18.2 M⊙ (Aragona et al. 2010, ApJ, 724, 306), unless the inclination is extremely small. The photon index indicates that the spectra become softer when the system is bright. These suggest that the compact object is a pulsar.

On the Nature of the Enigmatic Object IRAS 19312+1950: A Rare Phase of Massive Star Formation?

NASA Technical Reports Server (NTRS)

Cordiner, M. A.; Boogert, A. C. A.; Charnley, S. B.; Justtanont, K.; Cox, N. L. J.; Smith, R. G.; Tielens, A. G. G. M.; Wirstrom, E. S.; Milam, S. N.; Keane, J. V.

2016-01-01

IRAS?19312+1950 is a peculiar object that has eluded firm characterization since its discovery, with combined maser properties similar to an evolved star and a young stellar object (YSO). To help determine its true nature, we obtained infrared spectra of IRAS?19312+1950 in the range 5-550 microns using the Herschel and Spitzer space observatories. The Herschel PACS maps exhibit a compact, slightly asymmetric continuum source at 170 microns, indicative of a large, dusty circumstellar envelope. The far-IR CO emission line spectrum reveals two gas temperature components: approx. = 0.22 Stellar Mass of material at 280+/-18 K, and ˜1.6 Me of material at 157+/-3 K. The OI 63 micron line is detected on-source but no significant emission from atomic ions was found. The HIFI observations display shocked, high-velocity gas with outflow speeds up to 90 km/s along the line of sight. From Spitzer spectroscopy, we identify ice absorption bands due to H2O at 5.8 microns and CO2 at 15 microns. The spectral energy distribution is consistent with a massive, luminous (approx. 2 × 10(exp 4) Stellar Luminosity) central source surrounded by a dense, warm circumstellar disk and envelope of total mass approx. 500-700 Stellar Mass with large bipolar outflow cavities. The combination of distinctive far-IR spectral features suggest that IRAS19312+1950 should be classified as an accreting, high-mass YSO rather than an evolved star. In light of this reclassification, IRAS19312+1950 becomes only the fifth high-mass protostar known to exhibit SiO maser activity, and demonstrates that 18 cm OH maser line ratios may not be reliable observational discriminators between evolved stars and YSOs.

Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948 0022 in March-July 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdo, A.A.; /Naval Research Lab, Wash., D.C. /Federal City Coll.; Ackermann, M.

Following the recent discovery of {gamma} rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to {gamma} rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to {gamma}-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the {gamma}-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest wasmore » at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.« less

Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948+0022 in 2009 March-July

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2009-11-25

For this research, following the recent discovery of γ rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to γ rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to γ-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the γ-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band.more » The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. In conclusion, these results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.« less

ON THE NATURE OF THE ENIGMATIC OBJECT IRAS 19312+1950: A RARE PHASE OF MASSIVE STAR FORMATION?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cordiner, M. A.; Charnley, S. B.; Milam, S. N.

IRAS 19312+1950 is a peculiar object that has eluded firm characterization since its discovery, with combined maser properties similar to an evolved star and a young stellar object (YSO). To help determine its true nature, we obtained infrared spectra of IRAS 19312+1950 in the range 5–550 μ m using the Herschel and Spitzer space observatories. The Herschel PACS maps exhibit a compact, slightly asymmetric continuum source at 170 μ m, indicative of a large, dusty circumstellar envelope. The far-IR CO emission line spectrum reveals two gas temperature components: ≈0.22 M {sub ⊙} of material at 280 ± 18 K, andmore » ≈1.6 M {sub ⊙} of material at 157 ± 3 K. The O i 63 μ m line is detected on-source but no significant emission from atomic ions was found. The HIFI observations display shocked, high-velocity gas with outflow speeds up to 90 km s{sup −1} along the line of sight. From Spitzer spectroscopy, we identify ice absorption bands due to H{sub 2}O at 5.8 μ m and CO{sub 2} at 15 μ m. The spectral energy distribution is consistent with a massive, luminous (∼2 × 10{sup 4} L {sub ⊙}) central source surrounded by a dense, warm circumstellar disk and envelope of total mass ∼500–700 M {sub ⊙}, with large bipolar outflow cavities. The combination of distinctive far-IR spectral features suggest that IRAS 19312+1950 should be classified as an accreting, high-mass YSO rather than an evolved star. In light of this reclassification, IRAS 19312+1950 becomes only the fifth high-mass protostar known to exhibit SiO maser activity, and demonstrates that 18 cm OH maser line ratios may not be reliable observational discriminators between evolved stars and YSOs.« less

Processing of presolar grains around post-AGB stars: SiC as the carrier of the ``21''μ m feature

NASA Astrophysics Data System (ADS)

Hofmeister, A. M.; Speck, A. K.

2003-12-01

Intermediate mass stars (0.8-8.0 Msolar) eventually evolve on the H-R diagram, up the asymptotic giant branch (AGB). The intensive mass loss which characterizes the AGB produces a circumstellar shell of dust and neutral gas. At the end of the AGB, mass loss virtually stops and the circumstellar shell begins to drift away from the star. At the same time the central star begins to shrink and heat up. This is the proto-planetary nebula (PPN) phase. Some PPNe exhibit an enigmatic feature in their infrared (IR) spectra at ˜21μ m. This feature is not seen in the spectra of either the precursors to PPNe, the AGB stars, or the successors of PPNe, ``normal'' planetary nebulae (PNe). However the ``21''μ m feature has been seen in the spectra of PNe with Wolf-Rayet central stars. Therefore the carrier of this feature is unlikely to be a transient species that only exists in the PPNe phase. This feature has been attributed to various molecular and solid state species, none of which satisfy all constraints, although titanium carbide (TiC) and polycyclic aromatic hydrocarbons (PAHs) have seemed the most viable. We present new laboratory data for silicon carbide (SiC) and show that it has a spectral feature which is a good candidate for the carrier of the 21μ m feature. The SiC spectral feature appears at approximately the same wavelength (depending on polytype/grain size) and has the same asymmetric profile as the observed astronomical feature. We suggest that processing and cooling of the SiC grains known to exist around carbon-rich AGB stars are responsible for the emergence of the enigmatic 21μ m feature. The emergence of this feature in the spectra of post-AGB stars demonstrates the processing of dust due to the changing physical environments around evolving stars.

Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution

PubMed Central

Cahill, James A.; Green, Richard E.; Fulton, Tara L.; Stiller, Mathias; Jay, Flora; Ovsyanikov, Nikita; Salamzade, Rauf; St. John, John; Stirling, Ian; Slatkin, Montgomery; Shapiro, Beth

2013-01-01

Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize. PMID:23516372

Genomic evidence for island population conversion resolves conflicting theories of polar bear evolution.

PubMed

Cahill, James A; Green, Richard E; Fulton, Tara L; Stiller, Mathias; Jay, Flora; Ovsyanikov, Nikita; Salamzade, Rauf; St John, John; Stirling, Ian; Slatkin, Montgomery; Shapiro, Beth

2013-01-01

Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize.

Mapping the Global Emergence of Batrachochytrium dendrobatidis, the Amphibian Chytrid Fungus

PubMed Central

Ronnenberg, Kathryn L.; Powell, Christopher I.; Walker, Susan F.; Bielby, Jon; Garner, Trenton W. J.; Weaver, George

2013-01-01

The rapid worldwide emergence of the amphibian pathogen Batrachochytrium dendrobatidis (Bd) is having a profound negative impact on biodiversity. However, global research efforts are fragmented and an overarching synthesis of global infection data is lacking. Here, we provide results from a community tool for the compilation of worldwide Bd presence and report on the analyses of data collated over a four-year period. Using this online database, we analysed: 1) spatial and taxonomic patterns of infection, including amphibian families that appear over- and under-infected; 2) relationships between Bd occurrence and declining amphibian species, including associations among Bd occurrence, species richness, and enigmatic population declines; and 3) patterns of environmental correlates with Bd, including climate metrics for all species combined and three families (Hylidae, Bufonidae, Ranidae) separately, at both a global scale and regional (U.S.A.) scale. These associations provide new insights for downscaled hypothesis testing. The pathogen has been detected in 52 of 82 countries in which sampling was reported, and it has been detected in 516 of 1240 (42%) amphibian species. We show that detected Bd infections are related to amphibian biodiversity and locations experiencing rapid enigmatic declines, supporting the hypothesis that greater complexity of amphibian communities increases the likelihood of emergence of infection and transmission of Bd. Using a global model including all sampled species, the odds of Bd detection decreased with increasing temperature range at a site. Further consideration of temperature range, rather than maximum or minimum temperatures, may provide new insights into Bd-host ecology. Whereas caution is necessary when interpreting such a broad global dataset, the use of our pathogen database is helping to inform studies of the epidemiology of Bd, as well as enabling regional, national, and international prioritization of conservation efforts. We

Mapping the global emergence of Batrachochytrium dendrobatidis, the amphibian chytrid fungus.

PubMed

Olson, Deanna H; Aanensen, David M; Ronnenberg, Kathryn L; Powell, Christopher I; Walker, Susan F; Bielby, Jon; Garner, Trenton W J; Weaver, George; Fisher, Matthew C

2013-01-01

The rapid worldwide emergence of the amphibian pathogen Batrachochytrium dendrobatidis (Bd) is having a profound negative impact on biodiversity. However, global research efforts are fragmented and an overarching synthesis of global infection data is lacking. Here, we provide results from a community tool for the compilation of worldwide Bd presence and report on the analyses of data collated over a four-year period. Using this online database, we analysed: 1) spatial and taxonomic patterns of infection, including amphibian families that appear over- and under-infected; 2) relationships between Bd occurrence and declining amphibian species, including associations among Bd occurrence, species richness, and enigmatic population declines; and 3) patterns of environmental correlates with Bd, including climate metrics for all species combined and three families (Hylidae, Bufonidae, Ranidae) separately, at both a global scale and regional (U.S.A.) scale. These associations provide new insights for downscaled hypothesis testing. The pathogen has been detected in 52 of 82 countries in which sampling was reported, and it has been detected in 516 of 1240 (42%) amphibian species. We show that detected Bd infections are related to amphibian biodiversity and locations experiencing rapid enigmatic declines, supporting the hypothesis that greater complexity of amphibian communities increases the likelihood of emergence of infection and transmission of Bd. Using a global model including all sampled species, the odds of Bd detection decreased with increasing temperature range at a site. Further consideration of temperature range, rather than maximum or minimum temperatures, may provide new insights into Bd-host ecology. Whereas caution is necessary when interpreting such a broad global dataset, the use of our pathogen database is helping to inform studies of the epidemiology of Bd, as well as enabling regional, national, and international prioritization of conservation efforts. We

End-Cretaceous akaganéite and its potential as a mineral marker of Deccan volcanism in the global sedimentary record

NASA Astrophysics Data System (ADS)

Font, Eric; Carlut, Julie; Rémazeilles, Céline; Mather, Tamsin; Nédélec, Anne; Mirão, José; Casale, Sandra

2017-04-01

Recently, we identified an enigmatic chlorine-rich iron (oxyhydr)oxide, together with mercury anomalies in End-Cretaceous marine sediments coeval with major eruptions of the Deccan Traps Magmatic Province. The mineral was observed in two remote sections, the Bidart section from the Basque-Cantabric Basin in the Atlantic Ocean, and the Gubbio (Bottacione) section in the Tethys realm, suggesting a global or at least widespread phenomenon. However, the exact nature and origin of this Cl-bearing mineral remained enigmatic. Here we present new results from the Bidart and Zumaya section, in the Basque Cantabric Basin, France and Spain. Micro-Raman analysis, Transmission (TEM) and Scanning (SEM) Electron Microscopy on Focused Ion Beam (FIB) foils were used in order to identify the accurate composition and nanostructure of the chlorine-rich mineral. Our results confirm akaganéite (β-FeOOH) as the main phase, with chlorine content of 3-5% of the total atomic weight. Our high-resolution TEM observations reveal that the micrometric-scale akaganéite particles are constituted by the aggregation of nanoparticles (nanorods) of akaganéite. Their internal structures contain empty spaces, suggesting formation in a low-density environment. Based on this new mineralogical evidence, we propose that the observed akaganéite was formed at low temperature and high altitude in the Deccan volcanic plume and was further transported to Bidart, Zumaya and Gubbio (where presence of akaganeite is inferred based on the similarity of the Cl-bearing minerals to the Bidart material) through the stratosphere. Therefore, akaganéite provides a potential new sedimentary marker to identify the imprint of the Deccan eruptions in the global stratigraphic record and is evidence of the broad distribution of volcanic halogen species at the start of the Cretaceous-Tertiary mass extinction. Publication supported by FCT- project UID/GEO/50019/2013 - Instituto Dom Luiz

Evaluations of Shorter Exposures of Contact Lens Cleaning Solutions against Fusarium oxysporum Species Complex and Fusarium solani Species Complex To Simulate Inappropriate Usage▿

PubMed Central

Ramani, Rama; Chaturvedi, Vishnu

2011-01-01

An outbreak of Fusarium keratitis in contact lens users resulted in withdrawal of ReNu with MoistureLoc solution, although the exact cause of the outbreak remains enigmatic. We evaluated current and discontinued multipurpose cleaning solutions (MPSs; MoistureLoc, Equate, MultiPlus, and OptiFree Express) against plankton- and biofilm-derived cells of Fusarium oxysporum species complex (FOSC) and F. solani species complex (FSSC). The methods included a traditional assay based on CFU counts and a novel flow cytometry (FC) assay based on percent cell subpopulation (PCS) stained with two fluorochromes (Sytox Red and 5-chloromethylfluorescein diacetate). The tests were done with the respective manufacturers' recommended cleaning regimens (240 to 360 min) and under shorter exposures (15 to 60 min) to simulate inappropriate usage by the customers. FC assay measured PCS, which was available rapidly, in 5 to 7 h, whereas 24 to 48 h was needed for CFU counts, and there was good correlation between the two methods (r2 = 0.97). FC assays allowed identification of injured fungal cells, which are likely to be missed with growth assays. In general, a time- and inoculum-dependent survival pattern was seen for both FOSC and FSSC cells, and biofilm-derived cells were more resistant than plankton-derived cells. MultiPlus and Equate produced 100% sterilization of fungi even under shorter exposures. However, biofilm FOSC and FSSC cells survived for up to 4 h in MoistureLoc solution and up to 6 h in OptiFree Express solution under shorter exposure times. This finding was enigmatic, as OptiFree Express is not associated with any outbreak of Fusarium keratitis. This study provides additional support for possible roles that improper lens cleaning regimens and fungal biofilms could play as predisposing factors for Fusarium keratitis. PMID:21300826

Topology search of 3-DOF translational parallel manipulators with three identical limbs for leg mechanisms

NASA Astrophysics Data System (ADS)

Wang, Mingfeng; Ceccarelli, Marco

2015-07-01

Three-degree of freedom(3-DOF) translational parallel manipulators(TPMs) have been widely studied both in industry and academia in the past decades. However, most architectures of 3-DOF TPMs are created mainly on designers' intuition, empirical knowledge, or associative reasoning and the topology synthesis researches of 3-DOF TPMs are still limited. In order to find out the atlas of designs for 3-DOF TPMs, a topology search is presented for enumeration of 3-DOF TPMs whose limbs can be modeled as 5-DOF serial chains. The proposed topology search of 3-DOF TPMs is aimed to overcome the sensitivities of the design solution of a 3-DOF TPM for a LARM leg mechanism in a biped robot. The topology search, which is based on the concept of generation and specialization in graph theory, is reported as a step-by-step procedure with desired specifications, principle and rules of generalization, design requirements and constraints, and algorithm of number synthesis. In order to obtain new feasible designs for a chosen example and to limit the search domain under general considerations, one topological generalized kinematic chain is chosen to be specialized. An atlas of new feasible designs is obtained and analyzed for a specific solution as leg mechanisms. The proposed methodology provides a topology search for 3-DOF TPMs for leg mechanisms, but it can be also expanded for other applications and tasks.

A model of cerebrocerebello-spinomuscular interaction in the sagittal control of human walking.

PubMed

Jo, Sungho; Massaquoi, Steve G

2007-03-01

A computationally developed model of human upright balance control (Jo and Massaquoi on Biol cybern 91:188-202, 2004) has been enhanced to describe biped walking in the sagittal plane. The model incorporates (a) non-linear muscle mechanics having activation level -dependent impedance, (b) scheduled cerebrocerebellar interaction for control of center of mass position and trunk pitch angle, (c) rectangular pulse-like feedforward commands from a brainstem/ spinal pattern generator, and (d) segmental reflex modulation of muscular synergies to refine inter-joint coordination. The model can stand when muscles around the ankle are coactivated. When trigger signals activate, the model transitions from standing still to walking at 1.5 m/s. Simulated natural walking displays none of seven pathological gait features. The model can simulate different walking speeds by tuning the amplitude and frequency in spinal pattern generator. The walking is stable against forward and backward pushes of up to 70 and 75 N, respectively, and with sudden changes in trunk mass of up to 18%. The sensitivity of the model to changes in neural parameters and the predicted behavioral results of simulated neural system lesions are examined. The deficit gait simulations may be useful to support the functional and anatomical correspondences of the model. The model demonstrates that basic human-like walking can be achieved by a hierarchical structure of stabilized-long loop feedback and synergy-mediated feedforward controls. In particular, internal models of body dynamics are not required.

Novel Door-opening Method for Six-legged Robots Based on Only Force Sensing

NASA Astrophysics Data System (ADS)

Chen, Zhi-Jun; Gao, Feng; Pan, Yang

2017-09-01

Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, especially using 0-DOF tools to operate and only force sensing to detect. A novel door-opening method for six-legged robots is developed and implemented to the six-parallel-legged robot. The kinematic model of the six-parallel-legged robot is established and the model of measuring the positional relationship between the robot and the door is proposed. The measurement model is completely based on only force sensing. The real-time trajectory planning method and the control strategy are designed. The trajectory planning method allows the maximum angle between the sagittal axis of the robot body and the normal line of the door plane to be 45º. A 0-DOF tool mounted to the robot body is applied to operate. By integrating with the body, the tool has 6 DOFs and enough workspace to operate. The loose grasp achieved by the tool helps release the inner force in the tool. Experiments are carried out to validate the method. The results show that the method is effective and robust in opening doors wider than 1 m. This paper proposes a novel door-opening method for six-legged robots, which notably uses a 0-DOF tool and only force sensing to detect and open the door.

Three-dimensional kinematics of the pelvis and hind limbs in chimpanzee (Pan troglodytes) and human bipedal walking.

PubMed

O'Neill, Matthew C; Lee, Leng-Feng; Demes, Brigitte; Thompson, Nathan E; Larson, Susan G; Stern, Jack T; Umberger, Brian R

2015-09-01

The common chimpanzee (Pan troglodytes) is a facultative biped and our closest living relative. As such, the musculoskeletal anatomies of their pelvis and hind limbs have long provided a comparative context for studies of human and fossil hominin locomotion. Yet, how the chimpanzee pelvis and hind limb actually move during bipedal walking is still not well defined. Here, we describe the three-dimensional (3-D) kinematics of the pelvis, hip, knee and ankle during bipedal walking and compare those values to humans walking at the same dimensionless and dimensional velocities. The stride-to-stride and intraspecific variations in 3-D kinematics were calculated using the adjusted coefficient of multiple correlation. Our results indicate that humans walk with a more stable pelvis than chimpanzees, especially in tilt and rotation. Both species exhibit similar magnitudes of pelvis list, but with segment motion that is opposite in phasing. In the hind limb, chimpanzees walk with a more flexed and abducted limb posture, and substantially exceed humans in the magnitude of hip rotation during a stride. The average stride-to-stride variation in joint and segment motion was greater in chimpanzees than humans, while the intraspecific variation was similar on average. These results demonstrate substantial differences between human and chimpanzee bipedal walking, in both the sagittal and non-sagittal planes. These new 3-D kinematic data are fundamental to a comprehensive understanding of the mechanics, energetics and control of chimpanzee bipedalism. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recruitment of human aquaporin 3 to internal membranes in the Plasmodium falciparum infected erythrocyte.

PubMed

Bietz, Sven; Montilla, Irine; Külzer, Simone; Przyborski, Jude M; Lingelbach, Klaus

2009-09-01

The molecular mechanisms underlying the formation of the parasitophorous vacuolar membrane in Plasmodium falciparum infected erythrocytes are incompletely understood, and the protein composition of this membrane is still enigmatic. Although the differentiated mammalian erythrocyte lacks the machinery required for endocytosis, some reports have described a localisation of host cell membrane proteins at the parasitophorous vacuolar membrane. Aquaporin 3 is an abundant plasma membrane protein of various cells, including mammalian erythrocytes where it is found in distinct oligomeric states. Here we show that human aquaporin 3 is internalized into infected erythrocytes, presumably during or soon after invasion. It is integrated into the PVM where it is organized in novel oligomeric states which are not found in non-infected cells.

Diabetes mellitus and the β-cell: the Last Ten Years

PubMed Central

Ashcroft, Frances M; Rorsman, Patrik

2018-01-01

Diabetes is a major global problem. During the past decade, the genetic basis of various monogenic forms of the disease, and their underlying molecular mechanisms, have been elucidated. Many genes that increase type-2 diabetes (T2DM) risk have also been identified but how they do so remains enigmatic. Nevertheless, defective insulin secretion emerges as the main culprit in both monogenic and polygenic diabetes, with environmental and lifestyle factors, via obesity, accounting for the current dramatic increase in T2DM. There also have been significant advances in therapy, particularly for some monogenic disorders. We review here what ails the beta-cell and how its function may be restored. PMID:22424227

Dynamical Instability Produces Transform Faults at Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Gerya, Taras

2010-08-01

Transform faults at mid-ocean ridges—one of the most striking, yet enigmatic features of terrestrial plate tectonics—are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps.

Under the mirror of the sleeping water: Poussin's Narcissus.

PubMed

Tutter, Adele

2014-12-01

Examined in conjunction with a close reading of Ovid's Metamorphoses, Nicolas Poussin's four paintings on the preoccupying theme of Narcissus and Echo reflect a developing aesthetic interpretation of its textual source. Poussin's reflective vision supports a radical reappraisal of the enigmatic myth at the heart of psychoanalytic theory and practice, in which Narcissus is construed as a far more object-related figure that seeks the formative, affirmative mirroring of the other. This in turn encourages a more versatile conceptualization of narcissistic disturbance, in which an etiologically heterogenous constellation of issues stems from a variety of disturbances in the myriad dynamic and developmental aspects of mirroring and attunement: the narcissisms. Copyright © 2014 Institute of Psychoanalysis.

Ancestor-descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata.

PubMed

Tsai, Cheng-Hsiu; Fordyce, R Ewan

2015-01-01

Ancestor-descendant relationships (ADRs), involving descent with modification, are the fundamental concept in evolution, but are usually difficult to recognize. We examined the cladistic relationship between the only reported fossil pygmy right whale, †Miocaperea pulchra, and its sole living relative, the enigmatic pygmy right whale Caperea marginata, the latter represented by both adult and juvenile specimens. †Miocaperea is phylogenetically bracketed between juvenile and adult Caperea marginata in morphologically based analyses, thus suggesting a possible ADR-the first so far identified within baleen whales (Cetacea: Mysticeti). The †Miocaperea-Caperea lineage may show long-term morphological stasis and, in turn, punctuated equilibrium. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Systems biology of seeds: deciphering the molecular mechanisms of seed storage, dormancy and onset of germination.

PubMed

Sreenivasulu, Nese

2017-05-01

Seeds are heterogeneous storage reserves with wide array of storage compounds that include various soluble carbohydrates, starch polymer, storage proteins and lipids. These stored reserves comprise 70% of the world's caloric intake in the form of food and animal feed produced through sustainable agriculture, which contributes to food and nutritional security. Seed systems biology remains an enigmatic subject in understanding seed storage processes, maturation and pre-germinative metabolism. The reviews and research articles covered in this special issue of Plant Cell Reports highlight recent advances made in the area of seed biology that cover various systems biology applications such as gene regulatory networks, metabolomics, epigenetics and the role of micro-RNA in seed development.

Anomalous Thermal Conductivity and Magnetic Torque Response in the Honeycomb Magnet α -RuCl3

NASA Astrophysics Data System (ADS)

Leahy, Ian A.; Pocs, Christopher A.; Siegfried, Peter E.; Graf, David; Do, S.-H.; Choi, Kwang-Yong; Normand, B.; Lee, Minhyea

2017-05-01

We report on the unusual behavior of the in-plane thermal conductivity κ and torque τ response in the Kitaev-Heisenberg material α -RuCl3 . κ shows a striking enhancement with linear growth beyond H =7 T , where magnetic order disappears, while τ for both of the in-plane symmetry directions shows an anomaly at the same field. The temperature and field dependence of κ are far more complex than conventional phonon and magnon contributions, and require us to invoke the presence of unconventional spin excitations whose properties are characteristic of a field-induced spin-liquid phase related to the enigmatic physics of the Kitaev model in an applied magnetic field.

Global patterns of predator diversity in the open oceans.

PubMed

Worm, Boris; Sandow, Marcel; Oschlies, Andreas; Lotze, Heike K; Myers, Ransom A

2005-08-26

The open oceans comprise most of the biosphere, yet patterns and trends of species diversity there are enigmatic. Here, we derive worldwide patterns of tuna and billfish diversity over the past 50 years, revealing distinct subtropical "hotspots" that appeared to hold generally for other predators and zooplankton. Diversity was positively correlated with thermal fronts and dissolved oxygen and a nonlinear function of temperature (approximately 25 degrees C optimum). Diversity declined between 10 and 50% in all oceans, a trend that coincided with increased fishing pressure, superimposed on strong El Niño-Southern Oscillation-driven variability across the Pacific. We conclude that predator diversity shows a predictable yet eroding pattern signaling ecosystem-wide changes linked to climate and fishing.

Hammer-toothed ‘marsupial skinks' from the Australian Cenozoic

PubMed Central

Arena, Derrick A.; Archer, Michael; Godthelp, Henk; Hand, Suzanne J.; Hocknull, Scott

2011-01-01

Extinct species of Malleodectes gen. nov. from Middle to Late Miocene deposits of the Riversleigh World Heritage Area, northwestern Queensland, Australia are enigmatic, highly specialized, probably snail-eating marsupials. Dentally, they closely resemble a bizarre group of living heterodont, wet forest scincid lizards from Australia (Cyclodomorphus) that may well have outcompeted them as snail-eaters when the closed forests of central Australia began to decline. Although there are scincids known from the same Miocene deposits at Riversleigh, these are relatively plesiomorphic, generalized feeders. This appears to be the most striking example known of dental convergence and possible competition between a mammal and a lizard, which in the long run worked out better for the lizards. PMID:21508033

Understanding Parkinson Disease: A Complex and Multifaceted Illness.

PubMed

Gopalakrishna, Apoorva; Alexander, Sheila A

2015-12-01

Parkinson disease is an incredibly complex and multifaceted illness affecting millions of people in the United States. Parkinson disease is characterized by progressive dopaminergic neuronal dysfunction and loss, leading to debilitating motor, cognitive, and behavioral symptoms. Parkinson disease is an enigmatic illness that is still extensively researched today to search for a better understanding of the disease, develop therapeutic interventions to halt or slow progression of the disease, and optimize patient outcomes. This article aims to examine in detail the normal function of the basal ganglia and dopaminergic neurons in the central nervous system, the etiology and pathophysiology of Parkinson disease, related signs and symptoms, current treatment, and finally, the profound impact of understanding the disease on nursing care.

Genomic relationship between SINE retrotransposons, Pol III–Pol II transcription, and chromatin organization: the journey from junk to jewel

PubMed Central

Lunyak, Victoria V.; Atallah, Michelle

2013-01-01

A typical eukaryotic genome harbors a rich variety of repetitive elements. The most abundant are retrotransposons, mobile retroelements that utilize reverse transcriptase and an RNA intermediate to relocate to a new location within the cellular genomes. A vast majority of the repetitive mammalian genome content has originated from the retrotransposition of SINE (100–300 bp short interspersed nuclear elements that are derived from the structural 7SL RNA or tRNA), LINE (7kb long interspersed nuclear element), and LTR (2–3 kb long terminal repeats) transposable element superfamilies. Broadly labeled as “evolutionary junkyard” or “fossils”, this enigmatic “dark matter” of the genome possesses many yet to be discovered properties. PMID:21916613

The Martian valley networks: Origin by niveo-fluvial processes

NASA Technical Reports Server (NTRS)

Rice, J. W., Jr.

1993-01-01

The valley networks may hold the key to unlocking the paleoclimatic history of Mars. These enigmatic landforms may be regarded as the Martian equivalent of the Rosetta Stone. Therefore, a more thorough understanding of their origin and evolution is required. However, there is still no consensus among investigators regarding the formation (runoff vs. sapping) of these features. Recent climatic modeling precludes warm (0 degrees C) globally averaged surface temperatures prior to 2 b.y. when solar luminosity was 25-30 percent less than present levels. This paper advocates snowmelt as the dominant process responsible for the formation of the dendritic valley networks. Evidence for Martian snowfall and subsequent melt has been discussed in previous studies.

[A new mechanism of ubiquitin-dependent proteolytic pathway--polyubiquitin chain recognition and proteasomal targeting].

PubMed

Kawahara, Hiroyuki; Yokosawa, Hideyoshi

2008-01-01

The RPN10 subunit of 26S proteasome and several UBA domain proteins can bind to the polyubiquitin chain and play a role as ubiquitin receptors of the 26S proteasome. Although it was thought that substrate recognition is an essential step in the proteasome-mediated protein degradation, deletion of rpn10 genes in yeast does not influence the viability of cells but instead causes only a mild phenotype, suggesting that the above ubiquitin receptors are redundantly involved in substrate delivery to the proteasome. However, their functional difference is still enigmatic. In this review, we summarize recent advances in polyubiquitin chain recognition/delivery system and provide potential applications to modulate this system as a probable target for drug development.

Impact Crater Deposits in the Martian Highlands

NASA Technical Reports Server (NTRS)

Mest, S. C.; Crown, D. a.

2005-01-01

The martian highlands of Noachis Terra (20-30 deg S, 20-50 deg E), Tyrrhena Terra (0-30 deg S, 50- 100 deg E) and Terra Cimmeria (0-60 deg S, 120-170 deg E) preserve long and complex histories of degradation, but the relative effects of such factors as fluvial, eolian, and mass wasting processes have not been well constrained. The effects of this degradation are best observed on large (D greater than 10 km) impact craters that characterize the ancient highlands. Some craters exhibit distinct interior deposits, but precise origins of these deposits are enigmatic; infilling may occur by sedimentary (e.g., fluvial, lacustrine, eolian), mass wasting and (or) volcanic processes.

Experimental testing of scattering polarization models

NASA Astrophysics Data System (ADS)

Li, Wenxian; Casini, Roberto; Tomczyk, Steven; Landi Degl'Innocenti, Egidio; Marsell, Brandan

2018-06-01

We realized a laboratory experiment to study the polarization of the Na I doublet at 589.3 nm, in the presence of a magnetic field. The purpose of the experiment is to test the theory of scattering polarization for illumination conditions typical of astrophysical plasmas. This work was stimulated by solar observations of the Na I doublet that have proven particularly challenging to reproduce with current models of polarized line formation, even casting doubts on our very understanding of the physics of scattering polarization on the Sun. The experiment has confirmed the fundamental correctness of the current theory, and demonstrated that the "enigmatic'' polarization of those observations is exclusively of solar origin.

The electromagnetic wave energy effect(s) in microwave-assisted organic syntheses (MAOS).

PubMed

Horikoshi, Satoshi; Watanabe, Tomoki; Narita, Atsushi; Suzuki, Yumiko; Serpone, Nick

2018-03-26

Organic reactions driven by microwaves have been subjected for several years to some enigmatic phenomenon referred to as the microwave effect, an effect often mentioned in microwave chemistry but seldom understood. We identify this microwave effect as an electromagnetic wave effect that influences many chemical reactions. In this article, we demonstrate its existence using three different types of microwave generators with dissimilar oscillation characteristics. We show that this effect is operative in photocatalyzed TiO 2 reactions; it negatively influences electro-conductive catalyzed reactions, and yet has but a negligible effect on organic syntheses. The relationship between this electromagnetic wave effect and chemical reactions is elucidated from such energetic considerations as the photon energy and the reactions' activation energies.

New findings of twisted-wing parasites (Strepsiptera) in Alaska

USGS Publications Warehouse

Mcdermott, Molly

2016-01-01

Strepsipterans are a group of insects with a gruesome life history and an enigmatic evolutionary past. Called ‘twisted-wing parasites’, they are minute parasitoids with a very distinct morphology (Figure 1). Alternatively thought to be related to ichneumon wasps, Diptera (flies), Coleoptera (beetles), and even Neuroptera (net-winged insects) (Pohl and Beutel, 2013); the latest genetic and morphological data support the sister order relationship of Strepsiptera and Coleoptera (Niehuis et al., 2012). Strepsipterans are highly modified, males having two hind wings and halteres instead of front wings or elytra. Unlike most parasitoids, they develop inside active, living insects who are sexually sterilized but not killed until or after emergence (Kathirithamby et al., 2015).

Portion of Pluto Sputnik Planum Sputnik Plain

NASA Image and Video Library

2015-07-17

This annotated view of a portion of Pluto's Sputnik Planum (Sputnik Plain), named for Earth's first artificial satellite, shows an array of enigmatic features. The surface appears to be divided into irregularly shaped segments that are ringed by narrow troughs, some of which contain darker materials. Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as a half-mile (1 kilometer) across are visible. The blocky appearance of some features is due to compression of the image. http://photojournal.jpl.nasa.gov/catalog/PIA19714

Harnessing complex emergent metaphors for effective communication in palliative care: a multimodal perceptual analysis of hospice patients' reports of transcendence experiences.

PubMed

Arnold, Bruce L; Lloyd, Linda S

2014-05-01

Terminally ill patients can have unexpected, enigmatic, and profound cognitive shifts that significantly alter their perception of themselves, thereby eliminating their fear of death and dying. However, there are no systematic studies into these remarkable yet ineffable transcendence experiences. They therefore remain easily overlooked or viewed as isolated anomalies and therefore excluded from quality-of-life patient considerations. We use a multimodal methodology for identifying the prevalence and thematic properties of complex emergent metaphors patients use to report these experiences. Although previous research has pioneered the importance of understanding conventional or primary metaphors at the end of life, our findings indicate the considerable potential of more complex metaphors for reducing barriers to effective communication in palliative care.

MDA5 and LGP2: Accomplices and Antagonists of Antiviral Signal Transduction

PubMed Central

Rodriguez, Kenny R.; Bruns, Annie M.

2014-01-01

Mammalian cells have the ability to recognize virus infection and mount a powerful antiviral transcriptional response that provides an initial barrier to replication and impacts both innate and adaptive immune responses. Retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) proteins mediate intracellular virus recognition and are activated by viral RNA ligands to induce antiviral signal transduction. While the mechanisms of RIG-I regulation are already well understood, less is known about the more enigmatic melanoma differentiation-associated 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2). Emerging evidence suggests that these two RLRs are intimately associated as both accomplices and antagonists of antiviral signal transduction. PMID:24850739

First captive breeding of the imperial parrot (Amazona imperialis).

PubMed

Reillo, Paul R; Durand, Stephen; Burton, Minchinton

2011-01-01

We describe the rearing and development of the first imperial parrot (Amazona imperialis) hatched and raised in captivity. A single egg was hen-incubated for 28 days, and the chick was parent-fed for ∼14 days, after which it was removed for hand-rearing. Similar to wild, parent-reared imperial nestlings, the chick developed fully within 12 weeks, weaning at 540 g body weight. Endangered and endemic to Dominica, the imperial is a vital flagship for oceanic rainforest conservation. Chronicling the neonatal development of A. imperialis helps illuminate the natural history of this enigmatic species, whose secretive nesting habits and low population density have frustrated a detailed understanding of its ecology and reproduction. © 2010 Wiley-Liss, Inc.

Zero-field dichroism in the solar chromosphere.

PubMed

Sainz, R Manso; Bueno, J Trujillo

2003-09-12

We explain the linear polarization of the Ca ii infrared triplet observed close to the edge of the solar disk. In particular, we demonstrate that the physical origin of the enigmatic polarizations of the 866.2 and 854.2 nm lines lies in the existence of atomic polarization in their metastable (2)D(3)(/2, 5/2) lower levels, which produces differential absorption of polarization components (dichroism). To this end, we have solved the problem of the generation and transfer of polarized radiation by taking fully into account all the relevant optical pumping mechanisms in multilevel atomic models. We argue that "zero-field" dichroism may be of great diagnostic value in astrophysics.

Toll-like receptor activation in the pathogenesis of lupus nephritis.

PubMed

Lorenz, Georg; Lech, Maciej; Anders, Hans-Joachim

2017-12-01

The pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis is complex but no longer enigmatic. Much progress has been made to on the polygenetic origin of lupus in identifying gene variants that permit the loss of tolerance against nuclear autoantigens. Along the same line in about 50% of lupus patients additional genetic weaknesses promote immune complex glomerulonephritis and filtration barrier dysfunction. Here we briefly summarize the pathogenesis of SLE with a focus on loss of tolerance and the role of toll-like receptors in the "pseudo"-antiviral immunity concept of systemic lupus. In addition, we discuss the local role of Toll-like receptors in intrarenal inflammation and kidney remodeling. Copyright © 2016 Elsevier Inc. All rights reserved.

Mastocytosis: current treatment concepts.

PubMed

Worobec, Alexandra S; Metcalfe, Dean D

2002-02-01

An explosion of research on mastocytosis in the last decade has witnessed a greater understanding of the molecular basis of this heterogeneous group of disorders and the conclusion that similar disease phenotypes may indeed be the result of different underlying genotypes. Along with our growing knowledge base of mastocytosis, newer approaches of treating these disorders are becoming available, all under investigational use at this time. This short review highlights the state of the art of current treatment strategies for the different categories of mastocytosis. The future will undoubtedly witness an even greater array of therapeutic options, as we continue to learn more about this enigmatic disease. Copyright 2002 S. Karger AG, Basel

Automatic detection of white-light flare kernels in SDO/HMI intensitygrams

NASA Astrophysics Data System (ADS)

Mravcová, Lucia; Švanda, Michal

2017-11-01

Solar flares with a broadband emission in the white-light range of the electromagnetic spectrum belong to most enigmatic phenomena on the Sun. The origin of the white-light emission is not entirely understood. We aim to systematically study the visible-light emission connected to solar flares in SDO/HMI observations. We developed a code for automatic detection of kernels of flares with HMI intensity brightenings and study properties of detected candidates. The code was tuned and tested and with a little effort, it could be applied to any suitable data set. By studying a few flare examples, we found indication that HMI intensity brightening might be an artefact of the simplified procedure used to compute HMI observables.

Book Review: The Origins of Comets

NASA Technical Reports Server (NTRS)

McKay, Christopher P.

1992-01-01

In The Origins of Comets, Bailey, Clube, and Napier propose that the answer to whether the ancient heavens were more interesting is a resounding "yes." The sky, in fact, has changed and is still changing. The authors trace the study of comets back to ancient Babylonian times with a focus on theories of the origins of these enigmatic visitors. The book is really of three distinct parts: the first six chapters provide an excellent and delightfully readable historical account of comet studies up to this century. The next few chapters give a rather detailed treatment of current models for comet origins. The last section treats the authors' own theories about the relationship between giant comets and extinctions on Earth.

[A new look at the tomb of the physician, Morlongo Venice].

PubMed

Pardon-Labonnelie, Muriel

2014-01-01

The development of the inventory and synthetic study of collyrium stamps, commonly known as "oculist's stamps", includes the physico-chemical analysis of rare stamped collyrium's remains. The fragments of collyrium which were discovered in a tomb of Morlungo (Veneto) are all the more remarkable as the remedy's name stamped on two of them remains enigmatic at the moment and because of the association in a funerary context with an-other thirty-five finds. More specifically, they were discovered near surgical bronze instruments, a large amount of amber, a portable sundial and a seal box. Recent archaeological, textual and technological data thus make the study of the remains of collyriums of Morlungo particularly interesting for the history of medicine.

Biogenic Potassium Salt Particles as Seeds for Secondary Organic Aerosol in the Amazon

NASA Astrophysics Data System (ADS)

Pöhlker, Christopher; Wiedemann, Kenia T.; Sinha, Bärbel; Shiraiwa, Manabu; Gunthe, Sachin S.; Smith, Mackenzie; Su, Hang; Artaxo, Paulo; Chen, Qi; Cheng, Yafang; Elbert, Wolfgang; Gilles, Mary K.; Kilcoyne, Arthur L. D.; Moffet, Ryan C.; Weigand, Markus; Martin, Scot T.; Pöschl, Ulrich; Andreae, Meinrat O.

2012-08-01

The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.

Are perytons signatures of ball lightning?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodin, I. Y.; Fisch, N. J.

2014-10-20

The enigmatic downchirped signals, called 'perytons', that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures maymore » be discarding events that have the same nature as known perytons.« less

Reactions of Standing Bipeds on Moving Platforms to Keep Their Balance May Increase the Amplitude of Oscillations of Platforms Satisfying Hooke’s Law

PubMed Central

Goldsztein, Guillermo H.

2016-01-01

Consider a person standing on a platform that oscillates laterally, i.e. to the right and left of the person. Assume the platform satisfies Hooke’s law. As the platform moves, the person reacts and moves its body attempting to keep its balance. We develop a simple model to study this phenomenon and show that the person, while attempting to keep its balance, may do positive work on the platform and increase the amplitude of its oscillations. The studies in this article are motivated by the oscillations in pedestrian bridges that are sometimes observed when large crowds cross them. PMID:27304857

The mitochondrial genome of Ifremeria nautilei and the phylogenetic position of the enigmatic deep-sea Abyssochrysoidea (Mollusca: Gastropoda).

PubMed

Osca, David; Templado, José; Zardoya, Rafael

2014-09-01

The complete nucleotide sequence of the mitochondrial (mt) genome of the deep-sea vent snail Ifremeria nautilei (Gastropoda: Abyssochrysoidea) was determined. The double stranded circular molecule is 15,664 pb in length and encodes for the typical 37 metazoan mitochondrial genes. The gene arrangement of the Ifremeria mt genome is most similar to genome organization of caenogastropods and differs only on the relative position of the trnW gene. The deduced amino acid sequences of the mt protein coding genes of Ifremeria mt genome were aligned with orthologous sequences from representatives of the main lineages of gastropods and phylogenetic relationships were inferred. The reconstructed phylogeny supports that Ifremeria belongs to Caenogastropoda and that it is closely related to hypsogastropod superfamilies. Results were compared with a reconstructed nuclear-based phylogeny. Moreover, a relaxed molecular-clock timetree calibrated with fossils dated the divergence of Abyssochrysoidea in the Late Jurassic-Early Cretaceous indicating a relatively modern colonization of deep-sea environments by these snails. Copyright © 2014 Elsevier B.V. All rights reserved.

Resolving the Dusty Circumstellar Structure of the Enigmatic Symbiotic Star CH Cygni with the MMT Adaptive Optics System

NASA Astrophysics Data System (ADS)

Biller, Beth A.; Close, Laird M.; Li, Aigen; Marengo, Massimo; Bieging, John H.; Hinz, Phil M.; Hoffmann, William F.; Brusa, Guido; Miller, Doug

2006-08-01

We imaged the symbiotic star CH Cyg and two PSF calibration stars using the unique 6.5 m MMT deformable secondary adaptive optics system. Our high-resolution (FWHM = 0.3"), very high Strehl (98%+/-2%), mid-infrared (9.8 and 11.7 μm) images of CH Cyg allow us to probe finer length scales than ever before for this object. CH Cyg is significantly extended compared to our unresolved PSF calibration stars (μ UMa and α Her) at 9.8 and 11.7 μm. We estimated the size of the extension by convolving a number of simple Gaussian models with the μ UMa PSF and determining which model provided the best fit to the data. Adopting the Hipparcos distance for this object of 270 pc, we found a nearly Gaussian extension with a FWHM at 9.8 μm of ~40.5+/-2.7 AU (0.15"+/-0.01") and a FWHM at 11.7 μm of 45.9+/-2.7 AU (0.17"+/-0.01"). After subtracting out the Gaussian component of the emission (convolved with our PSF), we found a faint ~ 0.7" asymmetric extension, which peaks in flux ~0.5" north of the stars. This extension is roughly coincident with the northern knotlike feature seen in HST WFPC2 images obtained in 1999. The results presented here made use of the of MMT Observatory, a facility jointly operated by the University of Arizona and the Smithsonian Institution.

Spring sapping origin of the enigmatic relict valleys of Cape Cod and Martha's Vineyard and Nantucket Islands, Massachusetts

USGS Publications Warehouse

Uchupi, E.; Oldale, R.N.

1994-01-01

Steep-sided, flat-floored linear valleys that lack well developed tributaries and end in amphitheater-like heads are eroded on the outwash plains of Cape Cod, Martha's Vineyard and Nantucket Island. The valleys are restricted from the mid to the distal ends of the outwash plains and show no connection to possible water sources at the updip end of the plains. Their distribution and morphology lead us to propose that they were eroded by groundwater seeps fed by proglacial lakes (the high hydrostatic heads of the lakes led to the elevation of the water table) dammed by the outwash plains and associated moraines. The valleys on Cape Cod were initiated by seeps along the foreset surfaces of sandy deltas emplaced in lakes in Nantucket Sound and Cape Cod Bay after these lakes drained. Those on Martha's Vineyard and Nantucket islands were either eroded by seeps at the distal ends of outwash plain wedges emplaced atop the subareal continental shelf south of the islands or along the foreset surfaces of sandy deltas emplaced on a lake behind a peripheral crustal bulge south of the glacial front. Valley erosion terminated after the lakes were drained and the water table dropped. ?? 1994.

Familial Cortical Myoclonic Tremor and Epilepsy, an Enigmatic Disorder: From Phenotypes to Pathophysiology and Genetics. A Systematic Review

PubMed Central

van den Ende, Tom; Sharifi, Sarvi; van der Salm, Sandra M. A.; van Rootselaar, Anne-Fleur

2018-01-01

Background Autosomal dominant familial cortical myoclonic tremor and epilepsy (FCMTE) is characterized by distal tremulous myoclonus, generalized seizures, and signs of cortical reflex myoclonus. FCMTE has been described in over 100 pedigrees worldwide, under several different names and acronyms. Pathological changes have been located in the cerebellum. This systematic review discusses the clinical spectrum, treatment, pathophysiology, and genetic findings. Methods We carried out a PubMed search, using a combination of the following search terms: cortical tremor, myoclonus, epilepsy, benign course, adult onset, familial, and autosomal dominant; this resulted in a total of 77 studies (761 patients; 126 pedigrees) fulfilling the inclusion and exclusion criteria. Results Phenotypic differences across pedigrees exist, possibly related to underlying genetic differences. A “benign” phenotype has been described in several Japanese families and pedigrees linked to 8q (FCMTE1). French patients (5p linkage; FCMTE3) exhibit more severe progression, and in Japanese/Chinese pedigrees (with unknown linkage) anticipation has been suggested. Preferred treatment is with valproate (mind teratogenicity), levetiracetam, and/or clonazepam. Several genes have been identified, which differ in potential pathogenicity. Discussion Based on the core features (above), the syndrome can be considered a distinct clinical entity. Clinical features may also include proximal myoclonus and mild progression with aging. Valproate or levetiracetam, with or without clonazepam, reduces symptoms. FCMTE is a heterogeneous disorder, and likely to include a variety of different conditions with mutations of different genes. Distinct phenotypic traits might reflect different genetic mutations. Genes involved in Purkinje cell outgrowth or those encoding for ion channels or neurotransmitters seem good candidate genes. PMID:29416935

A new case of the enigmatic Candidatus Neoehrlichia sp. (FU98) in a fox from the Czech Republic.

PubMed

Hodžić, Adnan; Mitkovà, Barbora; Modrý, David; Juránková, Jana; Frgelecová, Lucia; Forejtek, Pavel; Steinbauer, Vladimír; Duscher, Georg Gerhard

2017-02-01

This study reports a new case of Candidatus Neoehrlichia sp. (FU98) infection in a fox from the Czech Republic, and provides confirmatory evidence on the occurrence of this newly identified sequence type. However, further studies are needed to investigate the distribution, host range and possible vector(s) for this bacterium, as well as its impact on animals and humans. Copyright © 2016 Elsevier Ltd. All rights reserved.

The enigmatic nature of altruism in organ transplantation: a cross-cultural study of transplant physicians' views on altruism

PubMed Central

2010-01-01

Background Although altruism is a key principle in our current organ donation and transplantation system, the meanings and implications of the term have been widely debated. Recently, a new type of living organ donation--anonymous and non-directed, also called living altruistic donation (LAD)--has brought the issue into sharper focus. Transplant physicians' views on altruism might influence their attitudes and actions toward living altruistic donors. This study aimed to explore such views among transplant physicians in France and Quebec. Findings A total of 27 French and 19 Quebec transplant physicians participated in individual, semi-structured interviews between October 2004 and December 2005. The majority of these participants associated altruism with gratuitousness and saw altruistic acts as multiple and varied, ranging from showing consideration to saving a person's life. Conclusions The transplant physicians' discourses on altruism were quite diverse, leading us to question the relevance of the concept in organ transplantation and the appropriateness of the term "living altruistic donation." PMID:20673349

Chromosome Banding in Amphibia. XXXVI. Multimorphic Sex Chromosomes and an Enigmatic Sex Determination in Eleutherodactylus johnstonei (Anura, Eleutherodactylidae).

PubMed

Schmid, Michael; Steinlein, Claus

2018-01-01

A detailed cytogenetic study on the leaf litter frog Eleutherodactylus johnstonei from 14 different Caribbean islands and the mainlands of Venezuela and Guyana revealed the existence of multimorphic XY♂/XX♀ sex chromosomes 14. Their male sex determination and development depends either on the presence of 2 telocentric chromosomes 14 (XtYt), or on 1 submetacentric chromosome 14 (Xsm) plus 1 telocentric chromosome 14 (Yt), or on the presence of 2 submetacentric chromosomes 14 (XsmYsm). The female sex determination and development requires either the presence of 2 telocentric chromosomes 14 (XtXt) or 2 submetacentric chromosomes 14 (XsmXsm). In all individuals analyzed, the sex chromosomes 14 carry a prominent nucleolus organizer region in their long arms. An explanation is given for the origin of the (XtYt)♂, (XsmYt)♂, (XsmYsm)♂, (XtXt)♀, and (XsmXsm)♀ in the different populations of E. johnstonei. Furthermore, the present study gives detailed data on the chromosome banding patterns, in situ hybridization experiments, and the genome size of E. johnstonei. © 2018 S. Karger AG, Basel.

The Enigmatic Marine Reptile Nanchangosaurus from the Lower Triassic of Hubei, China and the Phylogenetic Affinities of Hupehsuchia

PubMed Central

Chen, Xiao-hong; Motani, Ryosuke; Cheng, Long; Jiang, Da-yong; Rieppel, Olivier

2014-01-01

The study of the holotype and of a new specimen of Nanchangosaurus suni (Reptilia; Diapsida; Hupehsuchia) revealed a suite of hitherto unrecognized characters. For example, Nanchangosaurus has bipartite neural spines and its vertebral count is nearly identical to that of Hupehsuchus. It differs from the latter in having poorly developed forelimbs despite the advanced ossification in the rest of the skeleton. Other differences all pertain to hupehsuchian plesiomorphies retained in Nanchangosaurus, such as low neural spines. The relationship of Hupehsuchia within Diapsida was analyzed based on a data matrix containing 41 taxa coded for 213 characters, of which 18 were identified as aquatic adaptations from functional inferences. These aquatic adaptations may be vulnerable to the argumentation of character homology because expectation for homoplasy is high. There is an apparent incongruence between phylogenetic signals from aquatic adaptations and the rest of the data, with aquatic adaptations favoring all marine reptiles but Helveticosaurus to form a super-clade. However, this super-clade does not obtain when aquatic adaptations were deleted, whereas individual marine reptile clades are all derived without them. We examined all possible combinations of the 18 aquatic adaptations (n = 262143) and found that four lineages of marine reptiles are recognized almost regardless of which of these features were included in the analysis: Hupehsuchia-Ichthyopterygia clade, Sauropterygia-Saurosphargidae clade, Thalattosauria, and Helveticosaurus. The interrelationships among these four depended on the combination of aquatic adaptations to be included, i.e., assumed to be homologous a priori by bypassing character argumentation. Hupehsuchia always appeared as the sister taxon of Ichthyopterygia. PMID:25014493

The enigmatic marine reptile nanchangosaurus from the lower triassic of Hubei, China and the phylogenetic affinities of Hupehsuchia.

PubMed

Chen, Xiao-hong; Motani, Ryosuke; Cheng, Long; Jiang, Da-yong; Rieppel, Olivier

2014-01-01

The study of the holotype and of a new specimen of Nanchangosaurus suni (Reptilia; Diapsida; Hupehsuchia) revealed a suite of hitherto unrecognized characters. For example, Nanchangosaurus has bipartite neural spines and its vertebral count is nearly identical to that of Hupehsuchus. It differs from the latter in having poorly developed forelimbs despite the advanced ossification in the rest of the skeleton. Other differences all pertain to hupehsuchian plesiomorphies retained in Nanchangosaurus, such as low neural spines. The relationship of Hupehsuchia within Diapsida was analyzed based on a data matrix containing 41 taxa coded for 213 characters, of which 18 were identified as aquatic adaptations from functional inferences. These aquatic adaptations may be vulnerable to the argumentation of character homology because expectation for homoplasy is high. There is an apparent incongruence between phylogenetic signals from aquatic adaptations and the rest of the data, with aquatic adaptations favoring all marine reptiles but Helveticosaurus to form a super-clade. However, this super-clade does not obtain when aquatic adaptations were deleted, whereas individual marine reptile clades are all derived without them. We examined all possible combinations of the 18 aquatic adaptations (n = 262143) and found that four lineages of marine reptiles are recognized almost regardless of which of these features were included in the analysis: Hupehsuchia-Ichthyopterygia clade, Sauropterygia-Saurosphargidae clade, Thalattosauria, and Helveticosaurus. The interrelationships among these four depended on the combination of aquatic adaptations to be included, i.e., assumed to be homologous a priori by bypassing character argumentation. Hupehsuchia always appeared as the sister taxon of Ichthyopterygia.

Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule

PubMed Central

Politi, Yael; Metzler, Rebecca A.; Abrecht, Mike; Gilbert, Benjamin; Wilt, Fred H.; Sagi, Irit; Addadi, Lia; Weiner, Steve; Gilbert, P. U. P. A.

2008-01-01

Sea urchin larval spicules transform amorphous calcium carbonate (ACC) into calcite single crystals. The mechanism of transformation is enigmatic: the transforming spicule displays both amorphous and crystalline properties, with no defined crystallization front. Here, we use X-ray photoelectron emission spectromicroscopy with probing size of 40–200 nm. We resolve 3 distinct mineral phases: An initial short-lived, presumably hydrated ACC phase, followed by an intermediate transient form of ACC, and finally the biogenic crystalline calcite phase. The amorphous and crystalline phases are juxtaposed, often appearing in adjacent sites at a scale of tens of nanometers. We propose that the amorphous-crystal transformation propagates in a tortuous path through preexisting 40- to 100-nm amorphous units, via a secondary nucleation mechanism. PMID:18987314

The MAGIC telescope for gamma-ray astronomy above 30 GeV

NASA Astrophysics Data System (ADS)

Moralejo, A.; MAGIC Collaboration

The MAGIC telescope is presently at its commissioning phase at the Roque de los Muchachos Observatory (ORM) on the island of La Palma. MAGIC will become the largest ground-based gamma ray telescope in the world, being sensitive to photons of energies as low as 30 GeV. The spectral range between 10 and 300 GeV remains to date mostly unexplored. Observations in this region of the spectrum are expected to provide key data for the understanding of a wide variety of astrophysical phenomena belonging to the so-called ``non thermal Universe'', like the processes in the nuclei of active galaxies, the radiation mechanisms of pulsars and supernova remnants, and the enigmatic gamma-ray bursts. And overview of the telescope and its Physics goals is presented.

Marte Valles Crater 'Island'

NASA Technical Reports Server (NTRS)

2004-01-01

10 April 2004 Marte Valles is an outflow channel system that straddles 180oW longitude between the region south of Cerberus and far northwestern Amazonis. The floor of the Marte valleys have enigmatic platy flow features that some argue are formed by lava, others suggest they are remnants of mud flows. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an island created in the middle of the main Marte Valles channel as fluid---whether lava or mud---flowed past two older meteor impact craters. The craters are located near 21.5oN, 175.3oW. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

Accretor: Generative Materiality in the Work of Driessens and Verstappen.

PubMed

Whitelaw, Mitchell

2015-01-01

Accretor, by the Dutch artists Erwin Driessens and Maria Verstappen, is a generative artwork that adopts and adapts artificial life techniques to produce intricate three-dimensional forms. This article introduces and analyzes Accretor, considering the enigmatic quality of the generated objects and in particular the role of materiality in this highly computational work. Accretor demonstrates a tangled continuity between digital and physical domains, where the constraints and affordances of matter inform both formal processes and aesthetic interpretations. Drawing on Arp's notion of the concrete artwork and McCormack and Dorin's notion of the computational sublime, the article finally argues that Accretor demonstrates what might be called a processual sublime, evoking expansive processes that span both computational and non-computational systems.

Neural correlates of humor detection and appreciation.

PubMed

Moran, Joseph M; Wig, Gagan S; Adams, Reginald B; Janata, Petr; Kelley, William M

2004-03-01

Humor is a uniquely human quality whose neural substrates remain enigmatic. The present report combined dynamic, real-life content and event-related functional magnetic resonance imaging (fMRI) to dissociate humor detection ("getting the joke") from humor appreciation (the affective experience of mirth). During scanning, subjects viewed full-length episodes of the television sitcoms Seinfeld or The Simpsons. Brain activity time-locked to humor detection moments revealed increases in left inferior frontal and posterior temporal cortices, whereas brain activity time-locked to moments of humor appreciation revealed increases in bilateral regions of insular cortex and the amygdala. These findings provide evidence that humor depends critically upon extant neural systems important for resolving incongruities (humor detection) and for the expression of affect (humor appreciation).

Genetic and genomic glimpses of the elusive arbuscular mycorrhizal fungi.

PubMed

Lanfranco, Luisa; Young, J Peter W

2012-08-01

Arbuscular mycorrhizal fungi (AMF), which form an ancient and widespread mutualistic symbiosis with plants, are a crucial but still enigmatic component of the plant microbiome. Nowadays, their obligate biotrophy is no longer an obstacle to deciphering the role played by AMF in this fascinating symbiosis. The first genome-wide transcriptomic analysis of an AMF showed a metabolic complexity with no sign of massive gene loss, and the presence of genes for meiotic recombination suggests that AMF are not simple clonal organisms, as originally thought. New findings on suppression of host defenses and nutrient exchange processes have shed light on the mechanisms that contribute to such an intimate and long-lasting integration between living plant and fungal cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

Neutron Spectroscopy Can Constrain the Composition and Provenance of Phobos and Deimos

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Lee, P.; Zolensky, M. E.; Mittelfehldt, D. W.; Lim, L.; Colaprete, A.

2016-01-01

The origin of the martian moons Phobos and Deimos is obscure and enigmatic. Hypotheses include the capture of asteroids originally from the outer main belt or beyond, residual material left over from Mars' formation, and accreted ejecta from a large impact on Mars, among others. Measurements of reflectance spectra indicate a similarity to dark, red D-type asteroids, but could indicate a highly space-weathered veneer. Here we suggest a way of constraining the near-surface composition of the two moons, for comparison to known meteoritic compositions. Neutron spectroscopy, particularly the thermal and epithermal neutron flux, distinguishes clearly between various classes of meteorites and varying hydrogen (water) abundances. Perhaps most surprising of all, a rendezvous with Phobos or Deimos is not necessary to achieve this.

Mitochondria: the next (neurode)generation

PubMed Central

Schon, Eric A.; Przedborski, Serge

2012-01-01

SUMMARY Adult-onset neurodegenerative disorders are disabling and often fatal diseases of the nervous system whose underlying mechanisms of cell death remain, in most instances, unknown. Defects in mitochondrial respiration had previously been proposed to contribute to the occurrence of many, if not all of the most common neurodegenerative disorders. However, the discovery of genes mutated in hereditary forms of these enigmatic diseases has additionally suggested defects in mitochondrial dynamics. Such disturbances can lead to changes in mitochondrial trafficking, in interorganellar communication, and in mitochondrial quality control. These new mechanisms by which mitochondria may also be linked to neurodegeneration will likely have far-reaching implications for our understanding of the pathophysiology and treatment of adult-onset neurodegenerative disorders. PMID:21689593

The costs and benefits of occasional sex: theoretical predictions and a case study.

PubMed

D'Souza, Thomas G; Michiels, Nico K

2010-01-01

Theory predicts that occasional sexual reproduction in predominantly parthenogenetic organisms offers all the advantages of obligate sexuality without paying its full costs. However, empirical examples identifying and evaluating the costs and benefits of rare sex are scarce. After reviewing the theoretical perspective on rare sex, we present our findings of potential costs and benefits of occasional sex in polyploid, sperm-dependent parthenogens of the planarian flatworm Schmidtea polychroa. Despite costs associated with the production of less fertile tetraploids as sexual intermediates, the benefits of rare sex prevail in S. polychroa and may be sufficiently strong to prevent extinction of parthenogenetic populations. This offers an explanation for the dominance of parthenogenesis in S. polychroa. We discuss the enigmatic question why not all organisms show a mixed reproduction mode.

Topography, surface properties, and tectonic evolution. [of Venus and comparison with earth

NASA Technical Reports Server (NTRS)

Mcgill, G. E.; Warner, J. L.; Malin, M. C.; Arvidson, R. E.; Eliason, E.; Nozette, S.; Reasenberg, R. D.

1983-01-01

Differences in atmospheric composition, atmospheric and lithospheric temperature, and perhaps mantle composition, suggest that the rock cycle on Venus is not similar to the earth's. While radar data are not consistent with a thick, widespread and porous regolith like that of the moon, wind-transported regolith could be cemented into sedimentary rock that would be indistinguishable from other rocks in radar returns. The elevation spectrum of Venus is strongly unimodal, in contrast to the earth. Most topographic features of Venus remain enigmatic. Two types of tectonic model are proposed: a lithosphere too thick or buoyant to participate in convective flow, and a lithosphere which, in participating in convective flow, implies the existence of plate tectonics. Features consistent with earth-like plate tectonics have not been recognized.

Giants among larges: how gigantism impacts giant virus entry into amoebae.

PubMed

Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Drumond, Betânia Paiva; Kroon, Erna Geessien

2016-06-01

The proposed order Megavirales comprises the nucleocytoplasmic large DNA viruses (NCLDV), infecting a wide range of hosts. Over time, they co-evolved with different host cells, developing various strategies to penetrate them. Mimiviruses and other giant viruses enter cells through phagocytosis, while Marseillevirus and other large viruses explore endocytosis and macropinocytosis. These differing strategies might reflect the evolution of those viruses. Various scenarios have been proposed for the origin and evolution of these viruses, presenting one of the most enigmatic issues to surround these microorganisms. In this context, we believe that giant viruses evolved independently by massive gene/size gain, exploring the phagocytic pathway of entry into amoebas. In response to gigantism, hosts developed mechanisms to evade these parasites. Copyright © 2016 Elsevier Ltd. All rights reserved.

Some current views on the origins and prospects of correlation optics.

PubMed

Angelsky, O V; Felde, Ch V; Polyanskii, P V

2016-04-20

The state of the art modern branch of optics and photonics now referred to as correlation optics is discussed in connection with both its origins and promising prospects. We use here the term "correlation" not only as a synonym of the term "coherence," but also for emphasizing the necessity of taking into account fine, sometimes enigmatic, phase relations among the components of complex optical fields, even if such fields are conventionally defined as completely coherent. Selection of topics for this brief review of correlation optics outlooks was not dictated by intention of comprehensive representation of this field of research, but rather by the scientific interests of the authors, ranging from classical theory of diffraction, holography, and light-scattering to modern singular optics.

Major role of planktonic phosphate reduction in the marine phosphorus redox cycle

NASA Astrophysics Data System (ADS)

Van Mooy, B. A. S.; Krupke, A.; Dyhrman, S. T.; Fredricks, H. F.; Frischkorn, K. R.; Ossolinski, J. E.; Repeta, D. J.; Rouco, M.; Seewald, J. D.; Sylva, S. P.

2015-05-01

Phosphorus in the +5 oxidation state (i.e., phosphate) is the most abundant form of phosphorus in the global ocean. An enigmatic pool of dissolved phosphonate molecules, with phosphorus in the +3 oxidation state, is also ubiquitous; however, cycling of phosphorus between oxidation states has remained poorly constrained. Using simple incubation and chromatography approaches, we measured the rate of the chemical reduction of phosphate to P(III) compounds in the western tropical North Atlantic Ocean. Colonial nitrogen-fixing cyanobacteria in surface waters played a critical role in phosphate reduction, but other classes of plankton, including potentially deep-water archaea, were also involved. These data are consistent with marine geochemical evidence and microbial genomic information, which together suggest the existence of a vast oceanic phosphorus redox cycle.

From Tunguska to Chelyabinsk via Jupiter

NASA Astrophysics Data System (ADS)

Artemieva, Natalia A.; Shuvalov, Valery V.

2016-06-01

The Tunguska event remained enigmatic for almost 100 years until the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994 helped to resolve this enigma and allowed us to adequately interpret the more recent Chelyabinsk event. Airbursts typically occur if a meteoroid entering Earth's atmosphere is 10-100 m in diameter, i.e., its energy ranges from 0.5 (Chelyabinsk) to 20 (Tunguska) Mt TNT. All this energy is released in the atmosphere with strong shock waves generated during the entry reaching the surface and causing substantial damage. Atmospheric plumes are capable of dispersing extraterrestrial materials worldwide. Modern civilization is extremely vulnerable to those relatively small disturbances that recur on a decadal timescale and are still difficult to predict.

Following the clues to neuropathic pain. Distribution and other leads reveal the cause and the treatment approach.

PubMed

Belgrade, M J

1999-11-01

Neuropathic pain can seem enigmatic at first because it can last indefinitely and often a cause is not evident. However, heightened awareness of typical characteristics, such as the following, makes identification fairly easy: The presence of certain accompanying conditions (e.g., diabetes, HIV or herpes zoster infection, multiple sclerosis) Pain described as shooting, stabbing, lancinating, burning, or searing Pain worse at night Pain following anatomic nerve distribution Pain in a numb or insensate site The presence of allodynia Neuropathic pain responds poorly to standard pain therapies and usually requires specialized medications (e.g., anticonvulsants, tricyclic antidepressants, opioid analgesics) for optimal control. Successful pain control is enhanced with use of a systematic approach consisting of disease modification, local or regional measures, and systemic therapy.

New paradigms in type 2 immunity.

PubMed

Pulendran, Bali; Artis, David

2012-07-27

Nearly half of the world's population harbors helminth infections or suffers from allergic disorders. A common feature of this population is the so-called "type 2 immune response," which confers protection against helminths, but also promotes pathologic responses associated with allergic inflammation. However, the mechanisms that initiate and control type 2 responses remain enigmatic. Recent advances have revealed a role for the innate immune system in orchestrating type 2 responses against a bewildering array of stimuli, from nanometer-sized allergens to 20-meter-long helminth parasites. Here, we review these advances and suggest that the human immune system has evolved multiple mechanisms of sensing such stimuli, from recognition of molecular patterns via innate immune receptors to detecting metabolic changes and tissue damage caused by these stimuli.

Endometriosis: translation of molecular insights to management.

PubMed

Langan, K L; Farrell, M E; Keyser, E A; Salyer, B A; Burney, R O

2014-09-01

Endometriosis is a debilitating gynecologic disorder causing pelvic pain and infertility and characterized by the implantation of endometrial tissue to extrauterine locations. Though aspects of the condition remain enigmatic, the molecular pathophysiology of endometriosis appears to be clarifying. Estrogen dependence of the disease is a sentinel endocrine feature and reduction of estrogen bioavailability is the therapeutic principle upon which traditional treatment and prevention approaches have been based. Endometriosis is a chronic inflammatory condition associated with lesional neoangiogenesis and attenuated progesterone action at the level of the endometrium. The elucidation of the molecular pathways mediating these observations has revealed new targets for directed medical and surgical treatment. This paper will review current approaches to the management of endometriosis in the context of the molecular pathophysiology.

Recent insights into the biology of Hodgkin lymphoma: unraveling the mysteries of the Reed-Sternberg cell.

PubMed

Roullet, Michele R; Bagg, Adam

2007-11-01

The microscopic pathology of Hodgkin lymphoma has been recognized for well over a century; however, only in the past 15 years has the enigmatic nature of this peculiar neoplasm been somewhat unraveled. This has been accomplished via a combination of the acquisition, via microdissection, of the prototypically rare malignant cells and their subsequent analysis via a variety of modalities, including genomic studies and expression profiling. This has facilitated the elucidation of the surreptitiously concealed B-cell origin of the cells, their complex but vital relationships with the surrounding micro- and macroenvironment, as well as multiple pathways involved in the pathobiology of this lymphoma. Understanding the intricacies of these intra- and extracellular pathways should allow for the development of less-toxic targeted therapies.

Novel neural pathways for metabolic effects of thyroid hormone.

PubMed

Fliers, Eric; Klieverik, Lars P; Kalsbeek, Andries

2010-04-01

The relation between thyrotoxicosis, the clinical syndrome resulting from exposure to excessive thyroid hormone concentrations, and the sympathetic nervous system remains enigmatic. Nevertheless, beta-adrenergic blockers are widely used to manage severe thyrotoxicosis. Recent experiments show that the effects of thyrotoxicosis on hepatic glucose production and insulin sensitivity can be modulated by selective hepatic sympathetic and parasympathetic denervation. Indeed, thyroid hormone stimulates hepatic glucose production via a sympathetic pathway, a novel central pathway for thyroid hormone action. Rodent studies suggest that similar neural routes exist for thyroid hormone analogues (e.g. thyronamines). Further elucidation of central effects of thyroid hormone on autonomic outflow to metabolic organs, including the thyroid and brown adipose tissue, will add to our understanding of hyperthyroidism. Copyright 2009 Elsevier Ltd. All rights reserved.

Genetic characterization of moaB mutants of Escherichia coli

PubMed Central

Kozmin, Stanislav G.; Schaaper, Roel M.

2013-01-01

The moaABCDE operon of Escherichia coli encodes enzymes essential for the biosynthesis of the molybdenum cofactor (Moco). However, the role of the moaB gene within this operon has remained enigmatic. Here, we have investigated the effect of moaB defects on two phenotypes diagnostic for Moco-deficiency: chlorate-resistance and sensitivity to the base analog 6-N-hydroxylaminopurine (HAP). We found that transposon insertions in moaB caused partial Moco-deficiency associated with chlorate-resistance, but not for HAP-sensitivity. On the other hand, in-frame deletions of moaB, or moaB overexpression, had no effect on either phenotype. Our combined data are consistent with the lack of any role for MoaB in Moco biosynthesis in E. coli. PMID:23680484

Molecular phylogeny of the squeak beetles, a family with disjunct Palearctic-Australian range.

PubMed

Hawlitschek, Oliver; Hendrich, Lars; Balke, Michael

2012-01-01

Many higher groups of plants and animals show distributional patterns which have been shown or have at some point in time been suggested to be correlated with plate tectonics and the ancient supercontinents Laurasia and Gondwana. Here, we study the family of squeak beetles (Coleoptera: Adephaga: Hygrobiidae) and its enigmatic distribution pattern, with one species in the Western Palearctic, one in China and four in Australia. We present a molecular phylogeny including five of the six extant species, showing the monophyly of the Australian radiation. We use a molecular clock approach, which indicates that Hygrobiidae is an ancient group dating back to the breakup of Pangea and discuss the possibility of vicariance as explanation for its current distribution. Copyright © 2011 Elsevier Inc. All rights reserved.

Kleptomania: a case series

PubMed Central

Saluja, Bharat; Chan, Lai Gwen; Dhaval, Dani

2014-01-01

Kleptomania is an enigmatic condition and is among the very few psychiatric disorders in which crime is medicalised and used as a legal defence. The scientific literature on kleptomania is scarce. Early literature and recent studies have shown a female preponderance, with an early age of onset of stealing in people with comorbid personality disorder(s). In a retrospective review of the case notes of theft offenders who had forensic psychiatric evaluations performed in a one-year period in 2010 at the Institute of Mental Health, Singapore, we found three patients who were diagnosed with kleptomania. In this report, we describe the pertinent clinical and sociodemographic characteristics, as well as the diagnostic issues of kleptomania in relation to the three cases. PMID:25630329

Freud's private mini-monograph on his own dreams. A contribution to the celebration of the centenary of The interpretation of dreams.

PubMed

Blum, H P

2001-10-01

A virtually unknown brief commentary by Freud on the characteristics of his own dreams is described and discussed. Freud's mini-monograph, discovered after some 80 years, has autobiographical, theoretical and organisational significance in the enigmatic context of the early development of psychoanalysis. Found among papers of Alfred Adler, this extraordinary document adds to our knowledge of psychoanalytic history, including the significance of dreams in the evolution of psychoanalytic thought. Freud's commentary permitted the identification of a particular dream as his own. This dream had been presented in anonymity to the fledgling Vienna Psychoanalytic Society for interpretation. The dream was later inserted, again anonymously, into The Interpretation of Dreams with Freud's own remarkable pre-oedipal interpretation. Freud's conflicted relationships with Adler and Jung are considered in historical context.