Freeze-thaw cycles drove chemical weathering and enriched sulfates in the Burns formation at Meridiani, Mars.

Sulfate-rich sedimentary rocks explored by the Opportunity rover during its 14-year surface mission at Meridiani Planum provide an invaluable window into the thousands of sulfate deposits detected on Mars via remote sensing. Existing models explaining the formation of martian sulfates can be generally described as either bottom-up, groundwater-driven playa settings or top-down icy chemical weathering environments. Here, we propose a hybrid model involving both bottom-up and top-down processes driven by freeze-thaw cycles. Freezing leads to cryo-concentration of acidic fluids from precipitations at the surface, facilitating rapid chemical weathering despite low temperatures. Cryosuction causes the upward migration of vadose water and even groundwater with dissolved ions, resulting in the accumulation of ions in near-surface environments. Evaporation precipitates salts, but leaching separates chlorides from sulfates during the thawing period. Freeze-thaw cycles, therefore, can enrich sulfates at the surface. While freeze-thaw is more commonly understood as a mechanism of physical weathering, we suggest that it is a fundamental aspect of chemical weathering on Mars.

Eigenimage2Eigenimage (E2E): A Self-Supervised Deep Learning Network for Hyperspectral Image Denoising.

The performance of deep learning-based denoisers highly depends on the quantity and quality of training data. However, paired noisy-clean training images are generally unavailable in hyperspectral remote sensing areas. To solve this problem, this work resorts to the self-supervised learning technique, where our proposed model can train itself to learn one part of noisy input from another part of noisy input. We study a general hyperspectral image (HSI) denoising framework, called Eigenimage2Eigenimage (E2E), which turns the HSI denoising problem into an eigenimage (i.e., the subspace representation coefficients of the HSI) denoising problem and proposes a learning strategy to generate noisy-noisy paired training eigenimages from noisy eigenimages. Consequently, the E2E denoising framework can be trained without clean data and applied to denoise HSIs without the constraint with the number of frequency bands. Experimental results are provided to demonstrate the performance of the proposed method that is better than the other existing deep learning methods for denoising HSIs. A MATLAB demo of this work is available at https://github.com/LinaZhuang/HSI-denoiser-Eigenimage2Eigenimagehttps://github.com/LinaZhuang/HSI-denoiser-Eigenimage2Eigenimage for the sake of reproducibility.

Bridge Plating of a First Proximal Phalanx Intra-articular Base Fracture-Benefits Over External Fixation.

A 62-year-old right-handed man presented with an intra-articular fracture of the proximal phalanx base of the right thumb after a motor vehicle accident. Computed tomography revealed severe comminution, apex volar angulation, and minimal bone stock at the proximal phalanx base. The patient consented to open reduction internal fixation with a locking plate to bridge the fracture and cancellous bone grafting of the distal radius. The hardware was removed at 8 weeks, without complications. The patient began therapy, and at 19 weeks following the surgery, the patient's thumb metacarpophalangeal joint motion was 10° to 30° and the interphalangeal motion was 30° to 50°. Radiographs showed fracture union and proper alignment, with modest shortening. The patient was satisfied with this result. Bridge plating may be an alternative to external fixation for certain thumb fractures, with the potential to maintain alignment and articular congruity while permitting earlier return to activities of daily living and avoiding the risk of pin-track infections.

Does a Reduced Secondary Operation Rate Offset Higher Implant Charges when Utilizing Suture Button Fixation for Syndesmotic Injuries?

OBJECTIVE: To determine whether a reduced secondary operation rate offsets higher implant charges when using suture button fixation for syndesmotic injuries. DESIGN: Retrospective cohort study. SETTING: Single, urban, Level 1 trauma center. PARTICIPANTS: Three-hundred twenty-seven (N = 327) skeletally mature patients with rotational ankle fractures (OTA/AO type 44) necessitating concurrent syndesmotic fixation. INTERVENTION: Suture button or solid 3.5-mm screw syndesmotic fixation. MAIN OUTCOME MEASUREMENTS: To compare implant charges with secondary operation charges based on differential implant removal rates between screws and suture buttons. RESULTS: Patients undergoing screw fixation were older (48.8 vs. 39.6 years, P < 0.01), had more ground-level fall mechanisms (59.3% vs. 51.1%, P = 0.026), and sustained fewer 44C type injuries (34.7% vs. 56.8%, P = 0.01). Implant removal occurred at a higher rate in the screw fixation group (17.6% vs. 5.7%, P = 0.005). Binomial logistic regression identified nonsmoker status (B = 1.03, P = 0.04) and implant type (B = 1.41, P = 0.008) as factors associated with implant removal. Adjusting for age, the NNT with a suture button construct to prevent one implant removal operation was 9, with mean resulting additional implant charges of $9747 ($1083/case). Backward calculations using data from previous large studies estimated secondary operation charges at approximately $14220, suggesting a potential 31.5% cost savings for suture buttons when considering reduced secondary operation rates. CONCLUSIONS: A reduced secondary operation rate may offset increased implant charges for suture button syndesmotic fixation when considering institutional implant removal rates for operations occurring in tertiary care settings. Given these offsetting charges, surgeons should use the syndesmotic fixation strategy they deem most appropriate in their practice setting. LEVEL OF EVIDENCE: Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The potential for floral evolution in response to competing selection pressures following the loss of hawkmoth pollination in Ruellia humilis.

PREMISE: In the absence of hawkmoth pollinators, chasmogamous (CH) flowers of Ruellia humilis self-pollinate by two secondary mechanisms. Other floral visitors might exert selection on CH floral traits to restore outcrossing, but at the same time preferential predation of CH seeds generates selection to increase the allocation of resources to cleistogamous (CL) flowers. METHODS: To assess the potential for an evolutionary response to these competing selection pressures, we estimated additive genetic variances ( σ A 2 ${\sigma }_{{\rm{A}}}^{2}$ ) and covariances for 14 reproductive traits and three fitness components in a Missouri population lacking hawkmoth pollinators. RESULTS: We found significant σ A 2 ${\sigma }_{{\rm{A}}}^{2}$ for all 11 floral traits and two measures of resource allocation to CL flowers, indicating the potential for a short-term response to selection on most reproductive traits. Selection generated by seed predators is predicted to increase the percentage of CL flowers by 0.24% per generation, and mean stigma-anther separation is predicted to decrease as a correlated response, increasing the fraction of plants that engage in prior selfing. However, the initial response to this selection is opposed by strong directional dominance. CONCLUSIONS: The predicted evolutionary decrease in the number of CH flowers available for potential outcrossing, combined with the apparent preclusion of potential diurnal pollinators by the pollen-harvesting activities of sweat bees, suggest that 100% cleistogamy is the likely outcome of evolution in the absence of hawkmoths. However, rare mutations with large effects, such as delaying budbreak until after sunrise, could provide pathways for the restoration of outcrossing that are not reachable by gradual quantitative-genetic evolution.

Initial Impact of the COVID-19 Pandemic on a US Orthopaedic Foot and Ankle Clinic.

Background: In the United States, the COVID-19 pandemic led to a nationwide quarantine that forced individuals to adjust their daily activities, potentially impacting the burden of foot and ankle disease. The purpose of this study was to compare diagnoses made in an orthopaedic foot and ankle clinic during the shelter-in-place period of the COVID-19 pandemic to diagnoses made during the same months of the previous year. Methods: A retrospective review of new patients presenting to the clinics of 4 fellowship-trained orthopaedic foot and ankle surgeons in a major United States city was performed. Patients in the COVID-19 group presented between March 22 and July 1, 2020, during the peak of the quarantine for this city. Patients in the control group presented during the same period of 2019. Final diagnosis, chronicity of symptoms (acute: ≤1 month), and mechanism of disease were compared between groups. Results: A total of 1409 new patient visits were reviewed with 449 visits in the COVID-19 group and 960 visits in the control group. The COVID-19 group had a significantly higher proportion of ankle fractures (8.7% vs 5.4%, P = .020) and stress fractures (4.2% vs 2.2%, P = .031), but a smaller proportion of Achilles tendon ruptures (0.7% vs 2.5%, P = .019). The COVID-19 group had a higher proportion of acute injuries (35.4% vs 23.5%, P < .001). Conclusion: There was a shift in prevalence of pathology seen in the foot and ankle clinic during the COVID-19 pandemic, which may reflect the adoption of different activities during the quarantine period and reluctance to present for evaluation of non-urgent injuries. Level of Evidence: Level III, retrospective cohort study.

Travel Distance Does Not Affect Outcomes After Arthroscopic Rotator Cuff Repair.

Purpose: To determine the effect of travel distance on achieving the minimal clinically important difference (MCID) on patient-reported outcome measures (PROMs) at least 1 year after arthroscopic rotator cuff repair (RCR). Methods: Patients undergoing primary arthroscopic RCR with a minimum 1-year follow-up at a high-volume tertiary referral center between May 2017 and June 2019 were retrospectively reviewed. Patients were divided into two groups: driving distance of >50 miles from the institution (referral group) and <50 miles (local group). American Shoulder and Elbow Score (ASES), Single Assessment Numeric Evaluation (SANE) score and Constant score at minimum 1-year follow-up were assessed. Chi-square analysis was used to analyze achievement of MCID on any PROM. Subgroup analysis by tear complexity (1 tendon vs. >2 tendons torn) was conducted. Logistic regression was performed to determine whether travel distance and other variables of interest had an effect on achieving MCID. Results: Of 996 patients reviewed, 385 patients (38.7%) had minimum 1-year follow-up. Of these, 62 (16%) traveled >50 miles to their orthopedic provider, and 212 (55%) had a complex tear. MCID for at least one PROM was reached by 305 (94%) patients in the local group and 56 (90%) patients in the referral group. There was no significant difference between groups in reaching MCID for any PROM. Subgroup analysis by tear complexity revealed no significant difference in preoperative PROMs or achieving MCID postoperatively between referral groups. There was no significant difference between groups when controlling for age, sex, adjusted gross income (AGI), primary health insurance, tear chronicity, and tear complexity. Conclusions: When controlling for age, sex, AGI, primary health insurance, tear chronicity, and tear complexity, distance to a high-volume shoulder arthroscopy surgery center did not have an effect on achieving the MCID for any PROM at least 1 year after arthroscopic RCR. Level of Evidence: Level III, retrospective cohort study.

Moderate Return to Play and Previous Performance After SLAP Repairs in Competitive Overhead Athletes: A Systematic Review.

PURPOSE: To perform a systematic review of return to play (RTP) and return to previous level of performance (RPP) in competitive overhead athletes after SLAP repair to identify factors associated with failure to RTP. METHODS: Systematic review was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Review was registered with PROSPERO International prospective register of systematic reviews (CRD42020215488). Inclusion criteria were literature reporting RTP or RPP following SLAP repair in overhead athletes were run in the following databases: PubMed/MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Google Scholar. Categories for data collection for each full article included (1) article information; (2) patient demographics; (3) surgical techniques; (4) level of competition; (5) rotator cuff treatment; (6) player position; (7) patient-reported outcome measures; and (8) RTP and RPP rates. The Methodological Index for Non-randomized Studies checklist was used to evaluate quality of all included studies. RESULTS: Eight studies with 333 subjects were identified. Overall RTP and RPP rates were 50% to 83.6% and 35.3% to 64%, respectively. Patients with surgically treated rotator cuff pathology had lower RTP (12.5%-64.7%) rates compared with those without (80.0%-83.6%). Professional athletes had similar RTP rates (62.5%-81.5%) compared with high-school (75.0%-90.0%) and college athletes (12.5%-83.3%). However, professional athletes demonstrated the lowest relative range of reported RPP rates (27.7%-55.6%). Pitchers had lower RTP (62.5%-80.0%) and RPP (52.0%-58.9%) compared with position players (91.3% RTP, 76.3%-78.2% RPP). CONCLUSIONS: Studies reviewed reported moderate RTP and RPP rates following SLAP repairs in competitive overhead athletes. Those with associated rotator cuff tear requiring treatment, and baseball pitchers were less likely to RTP and RPP. Professional athletes had similar RTP to an amateur; however, they were less likely to RPP. LEVEL OF EVIDENCE: Level IV, systematic review of Level III-IV studies.

Spontaneous Diabetic Myonecrosis Presenting as Acute Carpal Tunnel Syndrome.

A 57-year-old man with diabetes mellitus presented with a 4-day history of left palm pain out of proportion, with swelling, erythema, and dense median and ulnar nerve distribution sensory changes. Magnetic resonance imaging with and without contrast revealed diffuse hand edema and myonecrosis. The patient was treated surgically because the examination was concerning for acute carpal tunnel syndrome and ulnar nerve compression. Spontaneous diabetic myonecrosis is a complication of diabetes mellitus that can be confused with several other conditions. It presents as acute-onset painful swelling in any muscle, and in the hand, may cause compressive neuropathies that necessitate surgical intervention.

Intense subaerial weathering of eolian sediments in Gale crater, Mars.

After over 8 years of successful surface operations on Mars, the Curiosity rover has revealed much about the environment in Gale crater. Despite early observations of a lacustrine environment, few of the subsequent deposits exhibit demonstrable lacustrine character. We suggest instead that most of the stratigraphic section explored to date can be best explained as eolian and/or volcaniclastic sediments subaerially chemically weathered by acidic precipitation in a reduced atmosphere. Most of the deposits in Gale crater seemingly did not form in an ancient lake, but the results nonetheless shed considerable light on ancient climate, environmental change, and the astrobiology of Mars. Discoveries by Curiosity provide a critical piece to Mars' global alteration puzzle.

An integrated theoretical framework to explain interpersonal moralistic conflict.

This paper offers an integrated theoretical framework to explain interpersonal, moralistic conflict that combines the logic of the "pure sociology" approach with a social psychological framework that highlights the importance of the human capacity for language, evaluation, and justification. While violations of normative expectations are the root causes of moralistic conflict, the paper argues that one can only determine the emergence of such conflict by assessing the nature of the behavior in question in relation to the social locations of the participants in combination with the justifications invoked. The central question that the theory addresses can be distilled as follows: What explains the emergence of interpersonal, moralistic conflict? The paper specifies three core assumptions, followed by a delineation of a series of propositions designed to explicate the conditions under which moralistic conflicts emerge. The theory identifies the combination of the social geometry of interpersonal encounters along with the mechanisms that typically are used to justify the grievances that individuals express toward one another.

Cet article propose un cadre théorique intégré pour expliquer les conflits moraux interpersonnels qui combine la logique de l'approche de la "sociologie pure" avec un cadre psychologique social qui souligne l'importance de la capacité humaine de langage, d'évaluation et de justification. Si les violations des attentes normatives sont les causes profondes du conflit moraliste, l'article soutient que l'on ne peut déterminer l'émergence d'un tel conflit qu'en évaluant la nature du comportement en question par rapport à la situation sociale des participants, en combinaison avec les justifications invoquées. La question centrale que la théorie aborde peut être résumée comme suit : Qu'est-ce qui explique l'émergence d'un conflit interpersonnel et moraliste ? L'article spécifie trois hypothèses de base, suivies de la définition d'une série de propositions destinées à expliquer les conditions dans lesquelles les conflits moralistes émergent. La théorie identifie la combinaison de la géométrie sociale des rencontres interpersonnelles avec les mécanismes qui sont typiquement utilisés pour justifier les griefs que les individus expriment les uns envers les autres.

Jarosite formation in deep Antarctic ice provides a window into acidic, water-limited weathering on Mars.

Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. However, until now a similar geochemical process was not observed on Earth nor in other planetary settings. We report a multi-analytical indication of jarosite formation within deep ice. Below 1000 m depth, jarosite crystals adhering on residual silica-rich particles have been identified in the Talos Dome ice core (East Antarctica) and interpreted as products of weathering involving aeolian dust and acidic atmospheric aerosols. The progressive increase of ice metamorphism and re-crystallization with depth, favours the relocation and concentration of dust and the formation of acidic brines in isolated environments, allowing chemical reactions and mineral neo-formation to occur. This is the first described englacial diagenetic mechanism occurring in deep Antarctic ice and supports the ice-weathering model for jarosite formation on Mars, highlighting the geologic importance of paleo ice-related processes on this planet. Additional implications concern the preservation of dust-related signals in deep ice cores with respect to paleoclimatic reconstructions and the englacial history of meteorites from Antarctic blue ice fields.

Do Clinical Outcomes and Sagittal Parameters Differ Between Diabetics and Nondiabetics for Degenerative Spondylolisthesis Undergoing Lumbar Fusion?

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To assess the effect of diabetes mellitus (DM) on clinical and radiographic outcomes in patient with degenerative spondylolisthesis undergoing posterior lumbar spinal fusion. METHODS: Analysis of patients who underwent open posterior lumbar spinal fusion from 2011 to 2018. Patients being medically treated for DM were identified and separated from nondiabetic patients. Visual analogue scale Back/Leg pain and Oswestry Disability Index (ODI) were collected, and achievement of minimal clinically important difference was evaluated. Lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and PI-LL difference were measured on radiographs. Rates of postoperative complications were also collected. RESULTS: A total of 850 patients were included; 78 (9.20%) diabetic patients and 772 (90.80%) nondiabetic patients. Final PI-LL difference was significantly larger (P = .032) for patients with diabetes compared to no diabetes, but there were no other significant differences between radiographic measurements, operative time, or postoperative length of stay. There were no differences in clinical outcomes between the 2 groups. Diabetic patients were found to have a higher rate of discharge to a facility following surgery (P = .018). No differences were observed in reoperation or postoperative complication. CONCLUSIONS: While diabetic patients had more associated comorbidities compared with nondiabetic patients, they had similar patient-reported and radiographic outcomes. Similarly, there are no differences in rates of reoperation or postoperative complications. This study indicates that diabetic patients who have undergone thorough preoperative screening of related comorbidities and appropriate selection should be considered for lumbar spinal fusion.

Is There a Benefit to Modularity for Femoral Revisions When Using a Splined, Tapered Titanium Stem?

BACKGROUND: Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs monoblock splined, tapered titanium stems in revision THA. METHODS: We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2-17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included. RESULTS: There were no statistically significant differences in rates of reoperation (22.3% vs 17.9%; P = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .20) between groups. CONCLUSION: Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine whether modularity is beneficial for more complex femoral defects.

Defining Behavior and its Relationship to the Science of Psychology.

Even though the concept of behavior is central to modern psychology, there is no consensus regarding what the term behavior means. The current paper focuses on disentangling two separate conceptions of the term that have added to the confusion. One meaning of the term behavior pertains to natural scientific epistemology, specifically the requirements of empirical methodology and its reliance on data that are measurable and available to public observation. The second meaning pertains to ontology and relates to the fact that at a descriptive level there are different kinds of behavioral patterns in the universe. Put simply, inanimate material objects behave differently from living organisms, which behave differently from animals, which behave differently from people. This paper introduces a "Periodic Table of Behavior" derived from Henriques', Review of General Psychology, 7, 150-182, (2003, 2011) Tree of Knowledge System to map the different kinds of behaviors that are described and examined by different sciences. It concludes by using the formulation to clarify the relationship between the methodological and ontological description of behavior and argues how the basic science of psychology can be effectively defined as the science of mental behavior going forward.

Terrorism and lethal moralism in the United States and United Kingdom, 1970-2017.

The current paper examines terrorism as a special form of moralistic violence, with several key features that distinguish such behaviour from other types of violence. The theory of lethal moralism highlights the importance of social polarization, characterized by vast differences in social space and inequality between adversaries as crucial to explaining deadly terrorist attacks. Where the differences are more permanent or chronic - and the groups in question define and justify their existence specifically in contradistinction to 'other' groups - then the polarization intensifies and attacks tend to be more lethal. In contrast, groups that appeal to broader audiences or the general public as potential allies more often use non-lethal terrorism to their strategic advantage. The study examines the United States and the United Kingdom to classify each of more than 8,000 attacks between 1970 and 2017 in terms of their ideological orientations. The evidence highlights the arc of terrorism in relation to different types of groups, as well as confirms the more lethal nature of terrorism linked especially to radical Islam, right-wing religious extremists, hate groups, ethno-nationalist sectarian violence, and anti-government anarchists. Yet apart from the extensive use of terrorism associated with 'The Troubles' in Northern Ireland, the majority of terrorist attacks in the US and the UK have not produced deaths. Most terrorism instead has been perpetrated by groups aiming to rally support for a general cause and has been far less deadly on balance. The implications of these findings are discussed with a view toward developing more powerful explanatory models that focus on the socio-cultural contexts and justification frameworks that inspire extremism and the use of lethal moralism to settle disputes.

Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars.

The ancient rock record for Mars has long been at odds with climate modelling. The presence of valley networks, dendritic channels and deltas on ancient terrains points towards running water and fluvial erosion on early Mars1, but climate modelling indicates that long-term warm conditions were not sustainable2. Widespread phyllosilicates and other aqueous minerals on the Martian surface3-6 provide additional evidence that an early wet Martian climate resulted in surface weathering. Some of these phyllosilicates formed in subsurface crustal environments5, with no association with the Martian climate, while other phyllosilicate-rich outcrops exhibit layered morphologies and broad stratigraphies7 consistent with surface formation. Here, we develop a new geochemical model for early Mars to explain the formation of these clay-bearing rocks in warm and wet surface locations. We propose that sporadic, short-term warm and wet environments during a generally cold early Mars enabled phyllosilicate formation without requiring long-term warm and wet conditions. We conclude that Mg-rich clay-bearing rocks with lateral variations in mixed Fe/Mg smectite, chlorite, talc, serpentine and zeolite occurrences formed in subsurface hydrothermal environments, whereas dioctahedral (Al/Fe3+-rich) smectite and widespread vertical horizonation of Fe/Mg smectites, clay assemblages and sulphates formed in variable aqueous environments on the surface of Mars. Our model for aluminosilicate formation on Mars is consistent with the observed geological features, diversity of aqueous mineralogies in ancient surface rocks and state-of-the-art palaeoclimate scenarios.

Elevated olivine weathering rates and sulfate formation at cryogenic temperatures on Mars.

Large Hesperian-aged (~3.7 Ga) layered deposits of sulfate-rich sediments in the equatorial regions of Mars have been suggested to be evidence for ephemeral playa environments. But early Mars may not have been warm enough to support conditions similar to what occurs in arid environments on Earth. Instead cold, icy environments may have been widespread. Under cryogenic conditions sulfate formation might be blocked, since kinetics of silicate weathering are typically strongly retarded at temperatures well below 0 °C. But cryo-concentration of acidic solutions may counteract the slow kinetics. Here we show that cryo-concentrated acidic brines rapidly chemically weather olivine minerals and form sulfate minerals at temperatures as low as -60 °C. These experimental results demonstrate the viability of sulfate formation under current Martian conditions, even in the polar regions. An ice-hosted sedimentation and weathering model may provide a compelling description of the origin of large Hesperian-aged layered sulfate deposits on Mars.

Ancient hydrothermal seafloor deposits in Eridania basin on Mars.

The Eridania region in the southern highlands of Mars once contained a vast inland sea with a volume of water greater than that of all other Martian lakes combined. Here we show that the most ancient materials within Eridania are thick (>400 m), massive (not bedded), mottled deposits containing saponite, talc-saponite, Fe-rich mica (for example, glauconite-nontronite), Fe- and Mg-serpentine, Mg-Fe-Ca-carbonate and probable Fe-sulphide that likely formed in a deep water (500-1,500 m) hydrothermal setting. The Eridania basin occurs within some of the most ancient terrain on Mars where striking evidence for remnant magnetism might suggest an early phase of crustal spreading. The relatively well-preserved seafloor hydrothermal deposits in Eridania are contemporaneous with the earliest evidence for life on Earth in potentially similar environments 3.8 billion years ago, and might provide an invaluable window into the environmental conditions of early Earth.

Genetic and environmental integration of the hawkmoth pollination syndrome in Ruellia humilis (Acanthaceae).

Background and Aims: The serial homology of floral structures has made it difficult to assess the relative contributions of selection and constraint to floral integration. The interpretation of floral integration may also be clouded by the tacit, but largely untested, assumption that genetic and environmental perturbations affect trait correlations in similar ways. In this study, estimates of both the genetic and environmental correlations between components of the hawkmoth pollination syndrome are presented for chasmogamous flowers of Ruellia humilis , including two levels of control for serial homology. Methods: A greenhouse population for quantitative genetic analysis was generated by a partial diallel cross between field-collected plants. An average of 634 chasmogamous flowers were measured for each of eight floral traits that contribute to the hawkmoth syndrome. Genetic correlations (across parents) and environmental correlations (across replicate flowers) were estimated by restricted maximum likelihood. Key Results: Stigma height, anther height and floral tube length were very tightly integrated in their responses to both genetic and environmental perturbations. The inclusion of floral disc width as a control for serial homology suggests this integration is an adaptive response to correlational selection imposed by pollinators. In contrast, integration of non-homologous traits was low. Furthermore, when comparisons between the dimensions of serially homologous structures were excluded, the genetic and environmental correlation matrices showed little congruence. Conclusions: The results suggest that hawkmoths have imposed strong correlational selection on floral traits involved in the deposition and removal of pollen, and that this is a consequence of stabilizing selection on the relative positions of stigmas and anthers in the face of substantial flower size variation. Low integration of other floral traits, and conflicting patterns of genetic and environmental correlations among these traits, suggest weak or no correlational selection within the range of variability expressed within a population.