Testing the Hydrogen Peroxide-Water Hypothesis for Life on Mars with the TEGA instrument on the Phoenix Lander

Since Viking has conducted its life detection experiments on Mars, many missions have enhanced our knowledge about the environmental conditions on the Red Planet. However, the Martian surface chemistry and the Viking lander results remain puzzling. Non-biological explanations that favor a strong inorganic oxidant are currently favored (e.g., Mancinelli, 1989; Quinn and Zent, 1999; Klein, 1999, Yen et al., 2000), but problems remain regarding the life time, source, and abundance of that oxidant to account for the Viking observations (Zent and McKay, 1994). Alternatively, a hypothesis favoring the biological origin of a strong oxidizer has recently been advanced (Houtkooper and Schulze-Makuch, 2007). Here, we report about laboratory experiments that simulate the experiments to be conducted by the Thermal and Evolved Gas Analyzer (TEGA) instrument of the Phoenix lander, which is to descend on Mars in May 2008. Our experiments provide a baseline for an unbiased test for chemical versus biological responses, which can be applied at the time the Phoenix Lander transmits its first results from the Martian surface.Comment: 11 pages and 3 figure

Host associations of Ixodes scapularis (Acari: Ixodidae) in residential and natural settings in a Lyme disease-endemic area in New Jersey.

ABSTRACT We live-trapped small mammals and ßagged vegetation within wooded natural and residential landscapes to examine how any observed differences in small mammal species composition may inßuence Ixodes scapularis Say burdens and the abundance of host-seeking ticks. Two years of live trapping showed that Eastern chipmunks, Tamias striatus, were captured with signiÞcantly greater frequency in some residential areas than white-footed mice, Peromyscus leucopus, whereas the proportion of white-footed mouse captures was higher or similar to chipmunk captures in the undeveloped natural areas. Both mice and chipmunks seemed to adapt well to managed residential landscapes, with residential sites yielding similar or signiÞcantly greater numbers of captures compared with undeveloped sites. In areas where chipmunk captures outnumbered mice, larval tick burdens on mice were either higher or no different than in areas where few or no chipmunks were captured, in contrast to previous studies suggesting that alternate hosts should reduce larval burdens on mice. Chipmunks apparently play an important role in the Lyme disease transmission cycle in these residential settings

a route towards defined surface functionalization

We investigate the surface-catalyzed dissociation of the archetypal molecular switch azobenzene on the Cu(111) surface. Based on X-ray photoelectron spectroscopy, normal incidence X-ray standing waves and density functional theory calculations a detailed picture of the coverage-induced formation of phenyl nitrene from azobenzene is presented. Furthermore, a comparison to the azobenzene/Ag(111) interface provides insight into the driving force behind the dissociation on Cu(111). The quantitative decay of azobenzene paves the way for the creation of a defect free, covalently bonded monolayer. Our work suggests a route of surface functionalization via suitable azobenzene derivatives and the on surface synthesis concept, allowing for the creation of complex immobilized molecular systems

A CAM- and starch-deficient mutant of the facultative CAM species Mesembryanthemum crystallinum reconciles sink demands by repartitioning carbon during acclimation to salinity

In the halophytic species Mesembryanthemum crystallinum, the induction of crassulacean acid metabolism (CAM) by salinity requires a substantial investment of resources in storage carbohydrates to provide substrate for nocturnal CO2 uptake. Acclimation to salinity also requires the synthesis and accumulation of cyclitols as compatible solutes, maintenance of root respiration, and nitrate assimilation. This study assessed the hierarchy and coordination of sinks for carbohydrate in leaves and roots during acclimation to salinity in M. crystallinum. By comparing wild type and a CAM-/starch-deficient mutant of this species, it was sought to determine if other metabolic sinks could compensate for a curtailment in CAM and enable acclimation to salinity. Under salinity, CAM deficiency reduced 24 h photosynthetic carbon gain by >50%. Cyclitols were accumulated to comparable levels in leaves and roots of both the wild type and mutant, but represented only 5% of 24 h carbon balance. Dark respiration of leaves and roots was a stronger sink for carbohydrate in the mutant compared with the wild type and implied higher maintenance costs for the metabolic processes underpinning acclimation to salinity when CAM was curtailed. CAM required the nocturnal mobilization of >70% of primary carbohydrate in the wild type and >85% of carbohydrate in the mutant. The substantial allocation of carbohydrate to CAM limited the export of sugars to roots, and the root:shoot ratio declined under salinity. The data suggest a key role for the vacuole in regulating the supply and demand for carbohydrate over the day/night cycle in the starch-/CAM-deficient mutant

Advances in material and friction data for modelling of metal machining

This paper reviews recent advances in constitutive and friction data and models for simulation of metal machining. Phenomenological and physically-based constitutive models commonly used in machining simulations are presented and discussed. Other topics include experimental techniques for acquiring data necessary to identify the constitutive model parameters, and recent advances in modelling of tool-workpiece friction and experimental techniques to acquire friction data under machining conditions. Additionally, thermo-physical properties for thermal modelling of the machining process, and microstructure data for the chip and workpiece together with relevant experimental methods are discussed. Future research needs in each of the focused areas are highlighted

Transgenic expression of the dicotyledonous pattern recognition receptor EFR in rice leads to ligand-dependent activation of defense responses

Plant plasma membrane localized pattern recognition receptors (PRRs) detect extracellular pathogen-associated molecules. PRRs such as Arabidopsis EFR and rice XA21 are taxonomically restricted and are absent from most plant genomes. Here we show that rice plants expressing EFR or the chimeric receptor EFR::XA21, containing the EFR ectodomain and the XA21 intracellular domain, sense both Escherichia coli- and Xanthomonas oryzae pv. oryzae (Xoo)-derived elf18 peptides at sub-nanomolar concentrations. Treatment of EFR and EFR::XA21 rice leaf tissue with elf18 leads to MAP kinase activation, reactive oxygen production and defense gene expression. Although expression of EFR does not lead to robust enhanced resistance to fully virulent Xoo isolates, it does lead to quantitatively enhanced resistance to weakly virulent Xoo isolates. EFR interacts with OsSERK2 and the XA21 binding protein 24 (XB24), two key components of the rice XA21-mediated immune response. Rice-EFR plants silenced for OsSERK2, or overexpressing rice XB24 are compromised in elf18-induced reactive oxygen production and defense gene expression indicating that these proteins are also important for EFR-mediated signaling in transgenic rice. Taken together, our results demonstrate the potential feasibility of enhancing disease resistance in rice and possibly other monocotyledonous crop species by expression of dicotyledonous PRRs. Our results also suggest that Arabidopsis EFR utilizes at least a subset of the known endogenous rice XA21 signaling components

MyPathway Human Epidermal Growth Factor Receptor 2 Basket Study: Pertuzumab + Trastuzumab Treatment of a Tissue-Agnostic Cohort of Patients With Human Epidermal Growth Factor Receptor 2-Altered Advanced Solid Tumors

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The MyPathway multiple-basket study (ClinicalTrials.gov identifier: NCT02091141) is evaluating targeted therapies in nonindicated tumors with relevant molecular alterations. We assessed pertuzumab + trastuzumab in a tissue-agnostic cohort of adult patients with human epidermal growth factor receptor 2 (HER2)-amplified and/or -overexpressed and/or -mutated solid tumors. The primary end point was objective response rate (ORR); secondary end points included survival and safety. At data cutoff (March 2022), 346 patients with HER2 amplification and/or overexpression with/without HER2 mutations (n = 263), or HER2 mutations alone (n = 83) had been treated. Patients with HER2 amplification and/or overexpression had an ORR of 25.9% (68/263, 95% CI, 20.7 to 31.6), including five complete responses (urothelial [n = 2], salivary gland [n = 2], and colon [n = 1] cancers). Activity was higher in those with wild-type (ORR, 28.1%) versus mutated KRAS (ORR, 7.1%). Among patients with HER2 amplification, ORR was numerically higher in patients with immunohistochemistry (IHC) 3+ (41.0%; 32/78) or 2+ (21.9%; 7/32), versus 1+ (8.3%; 1/12) or no expression (0%; 0/20). In patients with HER2 mutations alone, ORR was 6.0% (5/83, 95% CI, 2.0 to 13.5). Pertuzumab + trastuzumab showed activity in various HER2-amplified and/or -overexpressed tumors with wild-type KRAS, with the range of activity dependent on tumor type, but had limited activity in the context of KRAS mutations, HER2 mutations alone, or 0-1+ HER2 expression

MyPathway Human Epidermal Growth Factor Receptor 2 Basket Study: Pertuzumab + Trastuzumab Treatment of a Tissue-Agnostic Cohort of Patients With Human Epidermal Growth Factor Receptor 2–Altered Advanced Solid Tumors

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. The MyPathway multiple-basket study (ClinicalTrials.gov identifier: NCT02091141) is evaluating targeted therapies in nonindicated tumors with relevant molecular alterations. We assessed pertuzumab + trastuzumab in a tissue-agnostic cohort of adult patients with human epidermal growth factor receptor 2 (HER2)–amplified and/or –overexpressed and/or –mutated solid tumors. The primary end point was objective response rate (ORR); secondary end points included survival and safety. At data cutoff (March 2022), 346 patients with HER2 amplification and/or overexpression with/without HER2 mutations (n = 263), or HER2 mutations alone (n = 83) had been treated. Patients with HER2 amplification and/or overexpression had an ORR of 25.9% (68/263, 95% CI, 20.7 to 31.6), including five complete responses (urothelial [n = 2], salivary gland [n = 2], and colon [n = 1] cancers). Activity was higher in those with wild-type (ORR, 28.1%) versus mutated KRAS (ORR, 7.1%). Among patients with HER2 amplification, ORR was numerically higher in patients with immunohistochemistry (IHC) 3+ (41.0%; 32/78) or 2+ (21.9%; 7/32), versus 1+ (8.3%; 1/12) or no expression (0%; 0/20). In patients with HER2 mutations alone, ORR was 6.0% (5/83, 95% CI, 2.0 to 13.5). Pertuzumab + trastuzumab showed activity in various HER2-amplified and/or -overexpressed tumors with wild-type KRAS, with the range of activity dependent on tumor type, but had limited activity in the context of KRAS mutations, HER2 mutations alone, or 0-1+ HER2 expression

A characterization of ASAS-SN core-collapse supernova environments with VLT+MUSE: I. Sample selection, analysis of local environments, and correlations with light curve properties

The analysis of core-collapse supernova (CCSN) environments can provide important information on the life cycle of massive stars and constrain the progenitor properties of these powerful explosions. The MUSE instrument at the VLT enables detailed local environment constraints of the progenitors of large samples of CCSNe. Using a homogeneous SN sample from the ASAS-SN survey has enabled us to perform a minimally biased statistical analysis of CCSN environments. We analyze 111 galaxies observed by MUSE that hosted 112 CCSNe detected or discovered by the ASAS-SN survey between 2014 and 2018. The majority of the galaxies were observed by the the AMUSING survey. Here we analyze the immediate environment around the SN locations and compare the properties between the different CCSN types and their light curves. We used stellar population synthesis and spectral fitting techniques to derive physical parameters for all HII regions detected within each galaxy, including the star formation rate (SFR), H$\alpha$ equivalent width (EW), oxygen abundance, and extinction. We found that stripped-envelope (SE) SNe occur in environments with a higher median SFR, H$\alpha$ EW, and oxygen abundances than SNe II and SNe IIn/Ibn. The distributions of SNe II and IIn are very similar, indicating that these events explode in similar environments. For the SESNe, SNe Ic have higher median SFRs, H$\alpha$ EWs, and oxygen abundances than SNe Ib. SNe IIb have environments with similar SFRs and H$\alpha$ EWs to SNe Ib, and similar oxygen abundances to SNe Ic. We also show that the postmaximum decline rate, $s$, of SNe II correlates with the H$\alpha$ EW, and that the luminosity and the $\Delta m_{15}$ parameter of SESNe correlate with the oxygen abundance, H$\alpha$ EW, and SFR at their environments. This suggests a connection between the explosion mechanisms of these events to their environment properties