Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer

Using derived temperatures from thermal-infrared instruments aboard orbiting spacecraft, we constrain the thermophysical properties, in the upper few meters, of the north polar residual cap of Mars. In line with previous authors we test a homogeneous thermal model (i.e., depth-independent thermal properties), simulating water ice of varying porosity against observed temperatures. We find that high thermal inertia (>1,000Jm(-2)K(-1)s(1/2) or 40% porosity) that densifies with depth into a zero-porosity ice layer at shallow depths (<0.5m). We interpret this as evidence of recent water ice accumulation. Our results along the edge of the residual cap imply that denser (<40% porosity) ice is present at the surface and coincides with lower albedo. These results suggest that older ice is undergoing exhumation along much of the residual cap margin. The results support recent water ice accumulation having occurred over specific regions, while ablation dominates in others. Plain Language Summary The polar regions of Mars host kilometer-thick stacks of water ice that have been built up over millions of years. At the north pole today, the top of this ice deposit is interacting with the Martian atmosphere. Whether or not ice at the surface is fluffy (like snow) or dense (like an ice slab) can provide useful information about the polar ice cap and recent climate. Multiple years of surface temperature measurements have been acquired by instruments aboard spacecraft in orbit around Mars. By comparing these values with temperature simulations, we can narrow down the type of ice near the surface. Our results show that the type of ice varies across the polar cap. Some regions appear to be a snow-like surface where the polar cap may be growing. Other regions, most notably along the edge of the polar cap, show denser ice that is likely older. The nature of the ice tells us about the current climate and how these kilometer-thick ice deposits form.Mars Data Analysis Program [NNX15AM62G]6 month embargo; first published: 09 April 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

The inseparability of sampling and time and its influence on attempts to unify the molecular and fossil records

The two major approaches to studying macroevolution in deep time are the fossil record and reconstructed relationships among extant taxa from molecular data. Results based on one approach sometimes conflict with those based on the other, with inconsistencies often attributed to inherent flaws of one (or the other) data source. What is unquestionable is that both the molecular and fossil records are limited reflections of the same evolutionary history, and any contradiction between them represents a failure of our existing models to explain the patterns we observe. Fortunately, the different limitations of each record provide an opportunity to test or calibrate the other, and new methodological developments leverage both records simultaneously. However, we must reckon with the distinct relationships between sampling and time in the fossil record and molecular phylogenies. These differences impact our recognition of baselines, and the analytical incorporation of age estimate uncertainty. These differences in perspective also influence how different practitioners view the past and evolutionary time itself, bearing important implications for the generality of methodological advancements, and differences in the philosophical approach to macroevolutionary theory across fields.Comment: 29 pages, 1 figure. All others contributed equally to this wor

Ökologische Milchviehzucht: Entwicklung und Bewertung züchterischer Ansätze unter Berücksichtigung der Genotyp x Umwelt-Interaktion und Schaffung eines Informationssystems für nachhaltige Zuchtstrategien

In dem Projekt wurden für verschiedene Merkmalskomplexe an zwei verschiedenen Datensätzen Genotyp x Umwelt-Interaktionen zwischen ökologischen und konventionellen Produktionssystemen geschätzt. Anhand Schweizer Daten wurden für Braunvieh und Fleckvieh für Milchleistungsmerkmale Korrelationen > 0.9 zwischen beiden Betriebsformen geschätzt, wohingegen die genetische Korrelationen für funktionale Merkmale (Rastzeit, Zellzahl) geringer (0.8 bis 0.9) waren. Diese Korrelationen konnten für die Rasse Holstein Friesian auf Grund einer Auswertung Deutscher Daten bestätigt werden. Generell liegt für Leistungsmerkmale keine und für funktionale Merkmale eine geringe Genotyp x Umwelt-Interaktion zwischen ökologischen und konventionellen Betrieben vor, wobei insbesondere für letztere die Informationsbasis begrenzt ist. Auswertungen der Betriebsdaten von > 450 ökologisch wirtschaftenden Milchviehbetrieben und Befragungen der Betriebsleiter haben ergeben, dass sich diese Betriebe in ihren züchterischen Zielen kaum und in ihrem züchterischen Handeln gar nicht von konventionellen Betrieben unterscheiden. Zuchtplanerische Rechnungen haben ergeben, dass unter den gefundenen genetischen Parametern weder ein geschlossenes noch ein offenes eigenes Zuchtprogramm im ökologischen Sektor wirtschaftlich gerechtfertigt ist. Vielmehr ist anzustreben, dass sich ökologisch wirtschaftende Milchviehbetriebe stärker aktiv an etablierten Zuchtprogrammen beteiligen, z.B. durch den stärkeren Einsatz von Testbullen. Es wird vorgeschlagen, aufgrund der bestehenden Teilzuchtwerte einen Ökologischen Gesamtzuchtwert zu entwickeln, in dem funktionale Merkmale stärker gewichtet werden. Ein im Projekt entwickeltes Internetportal und eine entsprechend angepasste Anpaarungssoftware kann die Umsetzung dieses Vorschlags unterstützen. Erforderlich ist allerdings eine vollständigere Erfassung der ökologischen Milchviehbetriebe als Voraussetzung für eine bessere Unterstützung der ökologischen Milchviehzucht

Epithelial Sodium Channel-Mediated Sodium Transport Is Not Dependent on the Membrane-Bound Serine Protease CAP2/Tmprss4.

The membrane-bound serine protease CAP2/Tmprss4 has been previously identified in vitro as a positive regulator of the epithelial sodium channel (ENaC). To study its in vivo implication in ENaC-mediated sodium absorption, we generated a knockout mouse model for CAP2/Tmprss4. Mice deficient in CAP2/Tmprss4 were viable, fertile, and did not show any obvious histological abnormalities. Unexpectedly, when challenged with sodium-deficient diet, these mice did not develop any impairment in renal sodium handling as evidenced by normal plasma and urinary sodium and potassium electrolytes, as well as normal aldosterone levels. Despite minor alterations in ENaC mRNA expression, we found no evidence for altered proteolytic cleavage of ENaC subunits. In consequence, ENaC activity, as monitored by the amiloride-sensitive rectal potential difference (ΔPD), was not altered even under dietary sodium restriction. In summary, ENaC-mediated sodium balance is not affected by lack of CAP2/Tmprss4 expression and thus, does not seem to directly control ENaC expression and activity in vivo

Sporadic sampling, not climatic forcing, drives observed early hominin diversity.

Paleoanthropologists have long been intrigued by the observed patterns of human evolution, including species diversity, and often invoked climatic change as the principal driver of evolutionary change. Here, we investigate whether the early hominin fossil record is of suitable quality to test these climate-forcing hypotheses. Specifically, we compare early hominin diversity to sampling metrics that quantify changes in fossil preservation and sampling intensity between 7 and 1 million years ago. We find that observed diversity patterns are governed by sporadic sampling and do not yield a genuine evolutionary signal. Many more fossil discoveries are required before existing hypotheses linking climate and evolution can be meaningfully tested.The role of climate change in the origin and diversification of early hominins is hotly debated. Most accounts of early hominin evolution link observed fluctuations in species diversity to directional shifts in climate or periods of intense climatic instability. None of these hypotheses, however, have tested whether observed diversity patterns are distorted by variation in the quality of the hominin fossil record. Here, we present a detailed examination of early hominin diversity dynamics, including both taxic and phylogenetically corrected diversity estimates. Unlike past studies, we compare these estimates to sampling metrics for rock availability (hominin-, primate-, and mammal-bearing formations) and collection effort, to assess the geological and anthropogenic controls on the sampling of the early hominin fossil record. Taxic diversity, primate-bearing formations, and collection effort show strong positive correlations, demonstrating that observed patterns of early hominin taxic diversity can be explained by temporal heterogeneity in fossil sampling rather than genuine evolutionary processes. Peak taxic diversity at 1.9 million years ago (Ma) is a sampling artifact, reflecting merely maximal rock availability and collection effort. In contrast, phylogenetic diversity estimates imply peak diversity at 2.4 Ma and show little relation to sampling metrics. We find that apparent relationships between early hominin diversity and indicators of climatic instability are, in fact, driven largely by variation in suitable rock exposure and collection effort. Our results suggest that significant improvements in the quality of the fossil record are required before the role of climate in hominin evolution can be reliably determined

On quantum mean-field models and their quantum annealing

This paper deals with fully-connected mean-field models of quantum spins with p-body ferromagnetic interactions and a transverse field. For p=2 this corresponds to the quantum Curie-Weiss model (a special case of the Lipkin-Meshkov-Glick model) which exhibits a second-order phase transition, while for p>2 the transition is first order. We provide a refined analytical description both of the static and of the dynamic properties of these models. In particular we obtain analytically the exponential rate of decay of the gap at the first-order transition. We also study the slow annealing from the pure transverse field to the pure ferromagnet (and vice versa) and discuss the effect of the first-order transition and of the spinodal limit of metastability on the residual excitation energy, both for finite and exponentially divergent annealing times. In the quantum computation perspective this quantity would assess the efficiency of the quantum adiabatic procedure as an approximation algorithm.Comment: 44 pages, 23 figure

Comparison of variant calling methods for whole genome sequencing data in dairy cattle

Accurate identification of SNPs from next-generation sequencing data is crucial for high-quality downstream analysis. Whole genome sequence data of 65 key ancestors of genotyped Swiss dairy populations were available for investigation (24 billion reads, 96.8% mapped to UMD31, 12x coverage). Four publically available variant calling programmes were assessed and different levels of pre-calling handling for each method were tested and compared. SNP concordance was examined with Illumina’s BovineHD Genotyping BeadChip®. Depending on variant calling software used, between 16,894,054 and 22,048,382 SNP were identified (multi-sample calling). A total of 14,644,310 SNP were identified by all four variant callers (multi-sample calling). InDel counts ranged from 1,997,791 to 2,857,754; 1,708,649 InDels were identified by all four variant callers. A minimum of pre-calling data handling resulted in the highest non-reference sensitivity and the lowest non-reference discrepancy rates

Global cooling as a driver of diversification in a major marine clade

Climate is a strong driver of global diversity and will become increasingly important as human influences drive temperature changes at unprecedented rates. Here we investigate diversification and speciation trends within a diverse group of aquatic crustaceans, the Anomura. We use a phylogenetic framework to demonstrate that speciation rate is correlated with global cooling across the entire tree, in contrast to previous studies. Additionally, we find that marine clades continue to show evidence of increased speciation rates with cooler global temperatures, while the single freshwater clade shows the opposite trend with speciation rates positively correlated to global warming. Our findings suggest that both global cooling and warming lead to diversification and that habitat plays a role in the responses of species to climate change. These results have important implications for our understanding of how extant biota respond to ongoing climate change and are of particular importance for conservation planning of marine ecosystems

Differences in efficacy of monepantel, derquantel and abamectin against multi-resistant nematodes of sheep

Drug resistance has become a global phenomenon in gastrointestinal nematodes of sheep, particularly resistance to macrocyclic lactones. New anthelmintics are urgently needed for both the control of infections with multi-resistant nematodes in areas where classical anthelmintics are no longer effective, and the prevention of the spread of resistance in areas where the problem is not as severe. Recently, two new active ingredients became commercially available for the treatment of nematode infections in sheep, monepantel (Zolvix®) and derquantel, the latter used only in a formulated combination with the macrocyclic lactone, abamectin (Startect®). In order to assess the potential of the new actives for the control and prevention of spread of anthelmintic resistance, two characterized multi-resistant field isolates from Australia were used in a GLP (good laboratory practice) conducted efficacy study in sheep. Eight infected sheep in each group were treated orally according to the product labels with 2.5 mg/kg body weight monepantel, 0.2 mg/kg abamectin, or with the combination of 2.0 mg/kg derquantel and 0.2 mg/kg abamectin. The results demonstrate that monepantel was fully effective against multi-resistant species, Trichostrongylus colubriformis and Haemonchus contortus (99.9%). In contrast, the combination of derquantel and abamectin was effective against T. colubriformis (99.9%), but was not effective against larval stages of the barber's pole worm H. contortus (18.3%)