Magnetism in all-carbon nanostructures with negative gaussian curvature

The electronic and magnetic properties of an sp2 bonded all-carbon nanostructure, consisting of a nanotube junction structurally related to schwarzite, were investigated. The spin density functional theory was used during the investigation. The electronic structure of different tetrapods was calculated using the density functional theory within the local spin density approximation (LSDA). It was found that particular systems, which were related to schwarzite and contain no under-coordinated carbon atoms, carry a net magnetic moment in the ground state. The effect of edge termination on the net magnetic moment of the tetrapod was also studied.open13713

Smooth Muscle Myosin Inhibition: A Novel Therapeutic Approach for Pulmonary Hypertension

Pulmonary hypertension remains a major clinical problem despite current therapies. In this study, we examine for the first time a novel pharmacological target, smooth muscle myosin, and determine if the smooth muscle myosin inhibitor, CK-2019165 (CK-165) ameliorates pulmonary hypertension.Six domestic female pigs were surgically instrumented to measure pulmonary blood flow and systemic and pulmonary vascular dynamics. Pulmonary hypertension was induced by hypoxia, or infusion of the thromboxane analog (U-46619, 0.1 µg/kg/min, i.v.). In rats, chronic pulmonary hypertension was induced by monocrotaline.CK-165 (4 mg/kg, i.v.) reduced pulmonary vascular resistance by 22±3 and 28±6% from baseline in hypoxia and thromboxane pig models, respectively (p<0.01 and 0.01), while mean arterial pressure also fell and heart rate rose slightly. When CK-165 was delivered via inhalation in the hypoxia model, pulmonary vascular resistance fell by 17±6% (p<0.05) while mean arterial pressure and heart rate were unchanged. In the monocrotaline model of chronic pulmonary hypertension, inhaled CK-165 resulted in a similar (18.0±3.8%) reduction in right ventricular systolic pressure as compared with sildenafil (20.3±4.5%).Inhibition of smooth muscle myosin may be a novel therapeutic target for treatment of pulmonary hypertension

FORM AND FUNCTION OF THE HOMINOID FOOT

This dissertation examines the relationship of form and function in the foot of four species of hominoid; Homo sapiens, Pan troglodytes, Gorilla gorilla, and Pongo pygmaeus. The study is both analytic and comparative; that is, objectives include both analysis of the funtioning of the anatomical system of the foot, and comparison of this system in several closely related organisms exhibiting very different types of positional behavior. The investigation utilizes the joint-link approach of Dempster, and focuses on the functional complex rather than the single structure. Analysis of a particular complex, such as a joint, integrates anatomical data relating to muscle and ligament size and disposition and joint configuration, with osteometric data pertaining to the size of articular surfaces and the shape and proportions of the osseus structures. Several new osteometric measurements have been derived which are more relevant in assessing function than previously used linear measures. The four species with which this study is concerned exhibit very different types of positional behavior. Chimpanzees exhibit the widest range of behavior, being at home in the trees or on the ground. Gorillas are more terrestrial but are also capable of arboreal activities. The foot of these African pongids is more generalized than that of humans or orangs. The mobile tarsus can be stabilized in certain positions, and the powerful hallux can be used in a wide range of prehensile and non-prehensile activities. Humans use the foot as a base of support and as a propulsive organ in bipedal striding and running. The stabilized tarsus and adducted hallux are used as levers in raising the center of gravity and are unsuited for activities in which the foot is used as a prehensile organ. The high, narrow tarsus, which adds resiliency to this part of the foot, necessitates a number of balancing adaptations to maintain body weight over the base of support and prevent uncontrolled movement and consequent strain at the talo-crural joint, in particular. For similar reasons, the long axes of the tibiae are parallel, and the plane of the talo-crural and subtalar joints are perpendicular to the line of gravity during bipedal activities. Orangs are highly arboreal, usually supporting the body using the limbs in tension in a small branch setting. The highly prehensile foot emphasizes the lateral digits rather than the hallux in grasping the substrate. The tarsus is extremely mobile, especially in inversion, in order to allow foot placement in a wide variety of positions. Increased mobility, which occurs at the talo-crural as well as the subtalar and transverse tarsal joints, is a result of differences between this and the other species in both osseus and soft-part (especially ligamentus) morphology. As a consequence, the tarsus is ill-suited for compressive weight-bearing, or for use as a lever for the plantar flexors of the foot in this species. In keeping with the emphasis on digital prehension, the lateral metatarsals and phalanges are extremely elongated, and the hallux is reduced in the orang. When the total morphological pattern of the foot is considered, it is apparent that humans and African pongids are more similar to each other than they are to orangs. Somewhat different conclusions may be drawn if single structures only are compared. Generalizations regarding both habitus and heritage are commonly made from limited comparisons of anatomical structures. Problems with this practice are discussed in this dissertation

Uranium oxidation and probable subaerial weathering of phosphatized limestone from the Pourtales Terrace

Phosphatized limestones from the Pourtales Terrace, Straits of Florida, have undergone fresh-water diagenesis, as shown by several selective petrologic features such as dissolution of aragonitic skeletal material and preservation and recrystallization of Mg-calcite. This interpretation is supported by the fact that greater than 94% of the uranium in these samples is in the U(V1) oxidation state. On the deeper Pourtales Escarpment, phosphatized limestones show no alteration features indicative of fresh-water diagenesis. The uranium in these samples is a mixture of U(1V) and U(V1) with oxidation-state ratios similar to other seafloor phosphorites. Our interpretation of these data is that uranium in the terrace samples was oxidized when that area was emergent. The karsted surface of the terrace, therefore, is a result of subaerial exposure of this portion of the Floridan platform. The escarpment samples were never above sea level, and so more closely retain their original uranium oxidation-state ratios

Spatial-temporal variation of low-frequency earthquake bursts near Parkfield, California

International audienceTectonic tremor (TT) and low-frequency earthquakes (LFEs) have been found in the deeper crust of various tectonic environments globally in the last decade. The spatial-temporal behaviour of LFEs provides insight into deep fault zone processes. In this study, we examine recurrence times from a 12-yr catalogue of 88 LFE families with ∼730 000 LFEs in the vicinity of the Parkfield section of the San Andreas Fault (SAF) in central California. We apply an automatic burst detection algorithm to the LFE recurrence times to identify the clustering behaviour of LFEs (LFE bursts) in each family. We find that the burst behaviours in the northern and southern LFE groups differ. Generally, the northern group has longer burst duration but fewer LFEs per burst, while the southern group has shorter burst duration but more LFEs per burst. The southern group LFE bursts are generally more correlated than the northern group, suggesting more coherent deep fault slip and relatively simpler deep fault structure beneath the locked section of SAF. We also found that the 2004 Parkfield earthquake clearly increased the number of LFEs per burst and average burst duration for both the northern and the southern groups, with a relatively larger effect on the northern group. This could be due to the weakness of northern part of the fault, or the northwesterly rupture direction of the Parkfield earthquake