A 40th deg and order gravitational field model for Mars

Understanding the origin and evolution of major photographic features on Mars, such as the hemispheric dichotomy and Tharsis rise, will require improved resolution of that planet's gravitational and topographic fields. The highest resolution gravity model for Mars published to date was derived from Doppler tracking data from the Mariner 9 and Viking 1 and 2 spacecraft, and is of 18th degree and order. That field has a maximum spatial resolution of approx. 600 km, which is comparable to that of the best topographic model. The resolution of previous gravity models was limited not by data density, but rather by the computational resources available at the time. Because this restriction is no longer a limitation, the Viking and Mariner data sets were reanalyzed and a gravitational field was derived complete to the 40th degree and order with a corresponding maximum spatial resolution of 300 km where the data permit

The Tumor Suppressor HHEX Inhibits Axon Growth when Prematurely Expressed in Developing Central Nervous System Neurons

Neurons in the embryonic and peripheral nervoussystem respond to injury by activating transcriptional programs supportive of axon growth, ultimately resulting in functional recovery. In contrast, neurons in the adult central nervous system (CNS) possess a limited capacity to regenerate axons after injury, fundamentally constraining repair. Activating pro-regenerative gene expression in CNS neurons is a promising therapeutic approach, but progress is hampered by incomplete knowledge of the relevant transcription factors. An emerging hypothesis is that factors implicated in cellular growth and motility outside the nervous system may also control axon growth in neurons. We therefore tested sixty-nine transcription factors, previously identified as possessing tumor suppressive or oncogenic properties in non-neuronal cells, in assays of neurite outgrowth. This screen identified YAP1 and E2F1 as enhancers of neurite outgrowth, and PITX1, RBM14, ZBTB16, and HHEX as inhibitors. Follow-up experiments are focused on the tumor suppressor HHEX, one of the strongest growth inhibitors. HHEX is widely expressed in adult CNS neurons, including corticospinal tract neurons after spinal injury, but is present only in trace amounts in immature cortical neurons and adult peripheral neurons. HHEX overexpression in early postnatal cortical neurons reduced both initial axonogenesis and the rate of axon elongation, and domain deletion analysis strongly implicated transcriptional repression as the underlying mechanism. These findings suggest a role for HHEX in restricting axon growth in the developing CNS, and substantiate the hypothesis that previously identified oncogenes and tumor suppressors can play conserved roles in axon extension

Modes of Fracture of Flat Bone: Fracture Direction and Stress

This study delineates the application of fractography to discern the multifaceted modes of fracture in flat bones, explicating the interplay between fracture directionality and stress states regarding the viscoelastic nature of bone. Despite the perceived brittleness, bone exhibits toughness, attributed to its intricate structure design and amalgamating properties of solid and viscous materials. This research elucidates the variegated fracture modes inherent to bone\u27s dualistic nature by examining fracture surfaces and identifying fracture markings using stereoscopic microscopy. Our observations across seven bone specimens reveal predominant fracture patterns from top to bottom in six instances, with a singular deviation where the fracture initiated from the bottom to the top. This anomalous pattern is hypothesized to be attributable to the distinctive thinness at the center of the seventh bone, suggesting that structure variations significantly influence the direction of fracture propagation under quasistatic impacts. This insight into the structural determinants of fracture directionality, underscored by the exception in our dataset, highlights the critical role of bone morphology in dictating fracture mechanics. Focusing on the differential thicknesses of the trabecular and cortical layers, we correlate the observed fracture patterns with the underlying stress mechanisms—whether from contact damage, bending, or inherent flaws. This quasistatic impact study, eschewing dynamic and static stresses, furthers our understanding of bone fracture mechanics under controlled yet physiologically relevant conditions. Our findings offer insights into flat bones\u27 structural vulnerabilities and mechanical behaviors under varying stress states. This research refines our comprehension of bone\u27s biomechanical properties in treating and preventing bone injury

Hierarchy of the Selberg zeta functions

We introduce a Selberg type zeta function of two variables which interpolates several higher Selberg zeta functions. The analytic continuation, the functional equation and the determinant expression of this function via the Laplacian on a Riemann surface are obtained.Comment: 14 page

Effect of Processing Route on Strain Controlled Low Cycle Fatigue Behavior of Polycrystalline NiAl

The present investigation examines the effects of manufacturing process on the total axial strain controlled low cycle fatigue behavior of polycrystalline NiAl at 1000 K, a temperature above the monotonic Brittle-to-Ductile Transition Temperature (BDTT). The nickel aluminide samples were produced by three different processing routes: hot isostatic pressing of pre- alloyed powders, extrusion of prealloyed powders, and extrusion of vacuum induction melted ingots. The LCF behavior of the cast plus extruded material was also determined at room temperature (below the BD77) for comparison to the high temperature data. The cyclic stress response, cyclic stress-strain behavior, and strain-life relationships were influenced by the alloy preparation technique and the testing temperature. Detailed characterization of the LCF tested samples was conducted by optical and electron microscopy to determine the variations in fracture and deformation modes and to determine any microstructural changes that occurred during LCF testing. The dependence of LCF properties on processing route was rationalized on the basis of starting microstructure, brittle-to-ductile transition temperature, deformation induced changes in the basic microstructure, deformation substructure, and synergistic interaction between the damage modes

Primary structure and spectroscopic studies of Neurospora copper metallothionein.

When Neurospora crassa is grown in the presence of Cu(II) ions, it accumulates the metal with the concomitant synthesis of a low molecular weight copper-binding protein. The molecule binds 6 g-atom of copper per mole protein (Mr = 2200) and shows a striking sequence homology to the zinc- and cadmium-binding vertebrate metallothioneins. Absorption, circular dichroism, and electron paramagnetic resonance spectroscopy of Neurospora metallothionein indicate the copper to be bound to cysteinyl residues as a Cu(I)-thiolate complex of the polymeric mu-thiolate structure [Cu(I)6RS7]-. This metal-binding mode is also in agreement with the unusual luminescence of the protein. Spectral perturbation studies with HgCl2 and p-(chloromercuri)benzoate suggest that the 6 Cu(I)ions are coordinated to the seven cysteinyl residues in the form of a single metal cluster. Neurospora apometallothionein is also capable of binding in vivo group IIB metal ions [Zn(II), Cd(II), and Hg(II)] as well as paramagnetic Co(II) ions with an overall metal-to-protein stoichiometry of 3. The spectroscopic properties of the fully substituted forms are indicative of a distorted tetrahedral coordination. However, metal titration of the apoprotein shows the third metal ion to be differently coordinated than the other two metal ions. This difference can be explained by the presence of only seven cysteine residues in Neurospora metallothionein as opposed to nine cysteine residues in the three-metal cluster of the mammalian metallothioneins

Analysis of traffic conflicts at big intersection types in urban areas

In the past decades, planners developed intersections for the caroriented city. Above all, they should handle motor vehicle traffic efficiently. Urban areas currently have a high proportion of private cars and, as a result, congestion and high CO2 emissions. At the same time, the importance of and demand for sustainable mobility is increasing. Pedestrians and cyclists are particularly vulnerable as the weakest road users. The goal of transport policy is to achieve “Vision Zero,” i.e., no serious injuries or fatalities in road traffic (Federal Ministry of Digital Affairs and Transport, 2022). Many accidents occur primarily at intersections and junctions. Road traffic authorities in Germany generally use accident data from the accident atlas as the basis for evaluating the road safety of intersections. Planners can improve traffic safety by avoiding critical situations. To this end, an intensive study of the development of conflicts as a precursor to accidents can provide further insights. The research in this project shows that such data on traffic conflicts are not available to road authorities. The project will investigate which and how many conflicts between pedestrian, bicycle, and motor vehicle traffic frequently occur at individual intersection types, such as signalized intersections or traffic circles. The initial goal of the project is to develop a survey concept. In the future, planners should be able to use this to quickly identify risks to pedestrian and bicycle traffic at the types of intersections studied. With the help of vehicle sensor data (e.g. from emergency brake assistants), further findings on the frequency and course of conflicts are to be derived. In addition, a methodology would be developed that will enable traffic planners and municipalities to carry out risk management for intersections in the future in order to improve traffic safety and promote local mobility. From the results of the conflict analysis, we will derive recommendations for transport planning and policy. An action guide will then present the recommendations. The end of the project will be in summer 2024

Mechanochemical Synthesis and Magnetic Characterization of Nanosized Cubic Spinel FeCr₂S₄ Particles

Nanosized samples of the cubic thiospinel FeCr2S4 were synthesized by ball milling of FeS and Cr2S3 precursors followed by a distinct temperature treatment between 500 and 800 °C. Depending on the applied temperature, volume weighted mean (Lvol) particle sizes of 56 nm (500 °C), 86 nm (600 °C), and 123 nm (800 °C) were obtained. All samples show a transition into the ferrimagnetic state at a Curie temperature TC of ∼ 167 K only slightly depending on the annealing temperature. Above TC, ferromagnetic spin clusters survive and Curie–Weiss behavior is observed only at T ≫ TC, with T depending on the heat treatments and the external magnetic field applied. Zero-field-cooled and field-cooled magnetic susceptibilities diverge significantly below TC in contrast to what is observed for conventionally solid-state-prepared polycrystalline samples. In the low-temperature region, all samples show a transition into the orbital ordered state at about 9 K, which is more pronounced for the samples heated to higher temperatures. This observation is a clear indication that the cation disorder is very low because a pronounced disorder would suppress this magnetic transition. The unusual magnetic properties of the samples at low temperatures and different external magnetic fields can be clearly related to different factors like structural microstrain and magnetocrystalline anisotropy

Ramanujan's 1ψ1_{1}\psi_1 summation, Hecke-type double sums, and Appell-Lerch sums

We use a specialization of Ramanujan's ${}_1\psi_1$ summation to give a new proof of a recent formula of Hickerson and Mortenson which expands a special family of Hecke-type double sums in terms of Appell-Lerch sums and theta functions.Comment: Identity $(2.2)$ was known to L. Kronecke