Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of ...the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.
We calculate the amplitude T
1
for forward doubly virtual Compton scattering in heavy-baryon chiral perturbation theory, to fourth order in the chiral expansion and with the leading contribution of ...the
N
form factor. This provides a model-independent expression for the amplitude in the low-momentum region, which is the dominant one for its contribution to the Lamb shift. It allows us to significantly reduce the theoretical uncertainty in the proton polarisability contributions to the Lamb shift in muonic hydrogen. We also stress the importance of consistency between the definitions of the Born and structure parts of the amplitude. Our result leaves no room for any effect large enough to explain the discrepancy between proton charge radii as determined from muonic and normal hydrogen.
Differential cross sections for Compton scattering from the proton have been measured at scattering angles of 55°, 90°, and 125° in the laboratory frame using quasimonoenergetic linearly (circularly) ...polarized photon beams with a weighted mean energy value of 83.4 MeV (81.3 MeV). These measurements were performed at the High Intensity Gamma-Ray Source facility at the Triangle Universities Nuclear Laboratory. The results are compared to previous measurements and are interpreted in the chiral effective field theory framework to extract the electromagnetic dipole polarizabilities of the proton, which gives α_{E1}^{p}=13.8±1.2_{stat}±0.1_{BSR}±0.3_{theo},β_{M1}^{p}=0.2∓1.2_{stat}±0.1_{BSR}∓0.3_{theo} in units of 10^{-4} fm^{3}.
Interpreting measurements requires a physical theory, but the theory’s accuracy may vary across the experimental domain. To optimize experimental design, and so to ensure that the substantial ...resources necessary for modern experiments are focused on acquiring the most valuable data, both the theory uncertainty and the expected pattern of experimental errors must be considered. We develop a Bayesian approach to this problem, and apply it to the example of proton Compton scattering. Chiral Effective Field Theory (
χ
EFT) predicts the functional form of the scattering amplitude for this reaction, so that the electromagnetic polarizabilities of the nucleon can be inferred from data. With increasing photon energy, both experimental rates and sensitivities to polarizabilities increase, but the accuracy of
χ
EFT decreases. Our physics-based model of
χ
EFT truncation errors is combined with present knowledge of the polarizabilities and reasonable assumptions about experimental capabilities at HI
γ
S and MAMI to assess the information gain from measuring specific observables at specific kinematics,
i.e.
to determine the relative amount by which new data are apt to shrink uncertainties. The strongest gains would likely come from new data on the spin observables
Σ
2
x
and
Σ
2
x
′
at
ω
≃
140
to 200 MeV and
40
∘
to
120
∘
. These would tightly constrain
γ
E
1
E
1
-
γ
E
1
M
2
. New data on the differential cross section between 100 and 200 MeV and over a wide angle range will substantially improve constraints on
α
E
1
-
β
M
1
,
γ
π
and
γ
M
1
M
1
-
γ
M
1
E
2
. Good signals also exist around 160 MeV for
Σ
3
and
Σ
2
z
′
. Such data will be pivotal in the continuing quest to pin down the scalar polarizabilities and refine understanding of the spin polarizabilities.
The Procellarum region is a broad area on the nearside of the Moon that is characterized by low elevations, thin crust, and high surface concentrations of the heat-producing elements uranium, ...thorium, and potassium. The region has been interpreted as an ancient impact basin approximately 3,200 kilometres in diameter, although supporting evidence at the surface would have been largely obscured as a result of the great antiquity and poor preservation of any diagnostic features. Here we use data from the Gravity Recovery and Interior Laboratory (GRAIL) mission to examine the subsurface structure of Procellarum. The Bouguer gravity anomalies and gravity gradients reveal a pattern of narrow linear anomalies that border Procellarum and are interpreted to be the frozen remnants of lava-filled rifts and the underlying feeder dykes that served as the magma plumbing system for much of the nearside mare volcanism. The discontinuous surface structures that were earlier interpreted as remnants of an impact basin rim are shown in GRAIL data to be a part of this continuous set of border structures in a quasi-rectangular pattern with angular intersections, contrary to the expected circular or elliptical shape of an impact basin. The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the greater-than-average heat flux in the region.
While following up L dwarf candidates selected photometrically from the Two Micron All Sky Survey, we uncovered an unusual object designated 2MASS J01415823-4633574. Its optical spectrum exhibits ...very strong bands of vanadium oxide but abnormally weak absorptions by titanium oxide, potassium, and sodium. Morphologically, such spectroscopic characteristics fall intermediate between old field early-L dwarfs log(g) - 5 and very late M giants log(g) - 0, leading us to favor low gravity as the explanation for the unique spectral signatures of this L dwarf. Such a low gravity can be explained only if this L dwarf is much lower in mass than a typical old field L dwarf of similar temperature and is still contracting to its final radius. These conditions imply a very young age. Further evidence of youth is found in the near-infrared spectrum, including a triangular-shaped H-band continuum, reminiscent of young brown dwarf candidates discovered in the Orion Nebula Cluster. Using the above information along with comparisons to brown dwarf atmospheric and interior models, our current best estimate is that this L dwarf has an age of 1-50 Myr and a mass of 6-25M sub(J). Although the lack of a lithium detection (pseudo-equivalent width <1 AA) might appear to contradict other evidence of youth, we suggest that lithium becomes weaker at lower gravity like all other alkali lines and thus needs to be carefully considered before being used as a diagnostic of age or mass for objects in this regime. The location of 2MASS 0141-4633 on the sky coupled with a distance estimate of 635 pc and the above age estimate suggests that this object may be a brown dwarf member of either the 30 Myr old Tucana/Horologium association or the 612 Myr old b Pic moving group. Distance as determined through trigonometric parallax (underway) and a measure of the total space motion are needed to test this hypothesis.
Summary
Background
Epidermal homeostasis is maintained through the balance between keratinocyte proliferation, differentiation and desquamation; however, human skin equivalent (HSE) models are known ...to differentiate excessively. In native tissue, proteases such as kallikrein‐related peptidase (KLK) 5 and KLK7 cleave the extracellular components of corneodesmosomes; proteins corneodesmosin, desmocollin 1 and desmoglein 1, loosening the cellular connections and enabling desquamation. The actions of KLK7 are tightly controlled by protease inhibitors, skin‐derived antileucoproteinase (SKALP) and lymphoepithelial Kazal‐type‐related inhibitor (LEKTI), which also inhibits KLK5, localizing protease activity to the stratum corneum.
Objectives
To investigate the mechanisms that inhibit the desquamation cascade in HSE models.
Methods
Human skin tissue and HSE models were investigated using gene microarray, real‐time polymerase chain reaction (PCR), immunohistochemistry and Western blot analysis to examine key components of the desquamation pathway. To elucidate proteolytic activity in HSEs and native skin, in situ and gel zymography was performed.
Results
Histological analysis indicated that HSE models form a well‐organized epidermis, yet develop an excessively thick and compact stratum corneum. Gene microarray analysis revealed that the desquamation cascade was dysregulated in HSE models and this was confirmed using real‐time PCR and immunohistochemistry. Immunohistochemistry and Western blot indicated overexpression of LEKTI and SKALP in HSEs. Although KLK7 was also highly expressed in HSEs, zymography indicated that protease activation and activity was lower than in native skin.
Conclusions
These findings demonstrate that stratum corneum thickening is due to inhibited KLK5 and KLK7 activation and a subsequent lack of corneodesmosome degradation in the HSE model epidermis.
What's already known about this topic?
Corneocytes are sloughed from the skin surface in a process known as desquamation; this process is impaired in human skin equivalent (HSE) models.
The key enzymes involved in desquamation are kallikrein‐related peptidase (KLK)5 and KLK7, which cleave the extracellular cell–cell junction proteins corneodesmosin (CDSN), desmocollin 1 and desmoglein 1.
KLK5 and KLK7 are inhibited by lymphoepithelial Kazal‐type‐related inhibitor (LEKTI) and secreted antileucoprotease (SKALP).
What does this study add?
Altered desquamation is accompanied by aberrant localization of cell–cell junction proteins and protease inhibitors in HSE models.
KLK7 protein is overexpressed, neither KLK5 nor KLK7 are activated and overall epidermal proteolytic activity is lower in HSE models than native skin.
SKALP and LEKTI are present in the stratum corneum in HSEs, potentially inhibiting KLK7. CDSN protein persists in the stratum corneum, which suggests that it is not degraded.
What is the translational message?
These results provide a mechanistic insight into excess stratum corneum thickening in HSE models.
Epidermal homeostasis must be restored to generate HSE models with physiological expression, localization and activity of desquamation‐associated proteins for future translational studies.
Linked Comment: Brattsand. Br J Dermatol 2017; 176:11–12.
•A new in vitro, multi-cellular, human skin equivalent burn model was developed.•The model displays re-growth after burn injury, but burned native explant does not.•Silver dressing delayed or reduced ...skin re-growth after burn injury.•Silver particles were detected in the dermis using histology and mass-spectrometry.
In this study, a deep burn wound model was established using a 3D human skin equivalent (HSE) model and this was compared to native skin. HSEs were constructed from dermis derived from abdominoplasty/breast surgery and this dermal template was seeded with primary keratinocytes and fibroblasts. The HSE model was structurally similar to native skin with a stratified and differentiated epidermis. A contact burn (60 °C, 80 °C, 90 °C) was applied with a modified soldering iron and wounds were observed at day 1 and 7 after burn. The HSEs demonstrated re-growth with keratinocyte proliferation and formation of a neo-epidermis after burn injury, whereas the ex vivo native skin did not. To assess the suitability of the 3D HSE model for penetration and toxicity studies, a nanocrystalline silver dressing was applied to the model for 7 days, with and without burn injury. The effect of silver on skin re-growth and its penetration and subcellular localization was assessed in HSEs histologically and with laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The silver treatment delayed or reduced skin re-growth, and silver particles were detected on the top of the epidermis, and within the papillary dermis. This novel in vitro 3D multicellular deep burn wound model is effective for studying the pathology and treatment of burn wound injury and is suitable for penetration and toxicity studies of wound healing treatments.
Influenza A virus (IAV) is a common respiratory pathogen and a global cause of significant and often severe morbidity. Although inflammatory immune responses to IAV infections are well described, ...little is known about how neuroimmune processes contribute to IAV pathogenesis. In the present study, we employed surgical, genetic, and pharmacological approaches to manipulate pulmonary vagal sensory neuron innervation and activity in the lungs to explore potential crosstalk between pulmonary sensory neurons and immune processes. Intranasal inoculation of mice with H1N1 strains of IAV resulted in stereotypical antiviral lung inflammation and tissue pathology, changes in breathing, loss of body weight and other clinical signs of severe IAV disease. Unilateral cervical vagotomy and genetic ablation of pulmonary vagal sensory neurons had a moderate effect on the pulmonary inflammation induced by IAV infection, but significantly worsened clinical disease presentation. Inhibition of pulmonary vagal sensory neuron activity via inhalation of the charged sodium channel blocker, QX-314, resulted in a moderate decrease in lung pathology, but again this was accompanied by a paradoxical worsening of clinical signs. Notably, vagal sensory ganglia neuroinflammation was induced by IAV infection and this was significantly potentiated by QX-314 administration. This vagal ganglia hyperinflammation was characterized by alterations in IAV-induced host defense gene expression, increased neuropeptide gene and protein expression, and an increase in the number of inflammatory cells present within the ganglia. These data suggest that pulmonary vagal sensory neurons play a role in the regulation of the inflammatory process during IAV infection and suggest that vagal neuroinflammation may be an important contributor to IAV pathogenesis and clinical presentation. Targeting these pathways could offer therapeutic opportunities to treat IAV-induced morbidity and mortality.
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