Assimilation of Mars Climate Sounder Dust Observations: Challenges and Ways Forward

Introduction: Atmospheric dust is ubiquitous on Mars, and as a result of its absorption and scattering of radiation, is the key driver of the martian circulation. Accurately representing the complex spatial and temporal distribution of dust is therefore crucial for understanding Mars’ atmospheric dynamics. In particular, the vertical representation of the dust distribution in Mars’ atmosphere has been shown to have a significant effect on results from modelling and assimilation [1,2,3]. With the goal of more accurately representing this distribution, the assimilation of dust vertical information is a valuable technique which is being increasingly explored [4,5]. However, it brings with it its own challenges and methodological questions to be explored. Model and assimilation details: We use the LMD-UK Mars Global Circulation Model (MGCM), which solves the meteorological primitive equations of fluid dynamics, radiative and other parameterised physics to calculate the state of the martian atmosphere [6,7]. The UK version of the MGCM possesses a spectral dynamical core and semi-Lagrangian advection scheme [8], and is a collaboration between the Laboratoire de Météorologie Dynamique, The Open University, the University of Oxford, and the Instituto de Astrofisica de Andalucia. The model was run using a range of spectral and vertical resolutions, the latter spaced logarithmically. The assimilation scheme used was a modified version of the Analysis Correction scheme developed at the Met Office [9], adapted for use on Mars [10]. This method has the advantage of being computationally in-expensive, and its use of repeated insertion, weighted over a time window of about six hours, helps counter the issue of relaxation of the atmospheric state – an especially significant problem given the low thermal inertia of Mars’ atmosphere. Retrievals: The retrievals used in this study are from the Mars Climate Sounder (MCS) instrument aboard the Mars Reconnaissance Orbiter (MRO) [11], which now has amassed over five full martian years’ worth of data. For this study, the assimilated MCS variables were temperature and dust profiles. Temperature profiles extend from the surface to approximately 100 km, and dust profiles from as low as 10 km above the surface up to a maximum height of approximately 50 km. Retrieval of dust profiles allows MCS to observe the complex vertical dust structure in the atmosphere. The retrieval version used is 5.2, a re-processing using updated 2D geometry [12]. This results in improved retrievals, especially in the polar regions. While not used in this study, the NOMAD instrument aboard ExoMars TGO will soon provide another high-volume source of dust profiles alongside MCS [13], and should return observations with an even higher vertical resolution. Discussion: The assimilation of MCS dust profiles poses unique technical challenges, but presents the opportunity of representing Mars’ vertical dust distribution with unprecedented spatial and temporal accuracy within a GCM. Some outstanding questions for further experimentation and discussion include: What are the optimal spatial and, in particular, vertical model resolutions for assimilation of this data? Can dust profile assimilation aid in forecasting? Previous indirect assimilation of vertical dust via its MCS temperature signature has yielded a forecast time of 10 sols [5]; how dependent is this on the assimilation scheme and the choice of assimilating variables? How should we approach the bimodal nature of MCS local times? Should we give higher weighting to nightside dust observations, which tend to have better vertical coverage due to reduced scattering? And how much can we validly infer from the high day-night variability seen in MCS dust profiles? What are the best heuristics for filtering spurious opacities which could disrupt the assimilation, for example due to CO2 ice or surface reflectance [16])? What are the optimal ways of dealing with spatial and temporal gaps in the dataset? How can we best represent the dust distribution beyond the range of MCS, especially in the lowest 5-10 km of the atmosphere? What are the advantages and disadvantages of directly assimilating the dust field vs indirectly up-dating the dust field via its temperature signature, as seen in Fig. 1? Dust profile assimilation has been used to track individual dust storm events [4]; what can this tell us about storm formation and evolution, and can it be used for storm forecasting? How can we best constrain and validate the column optical depths of MCS dust profiles? Some ways forward regarding these questions will be explored, including comparative reanalyses and validation against different orbital datasets. Comparisons against MCS and other retrievals (such as NOMAD) should provide insight into the advantages of various in-model representations of features such as the dust distribution as well as the possible advantages or disadvantages of pruning the assimilated dataset. Meanwhile, alternate orbital or even ground-based sources of column opacity (such as Mars Express and MSL) could help better con-strain the distribution of dust not seen by MCS and offer clues how best to proceed in periods when MCS data is missing or limited. Some results of intercomparisons will be presented with the aim of fostering a more general discussion on MCS assimilation techniques. References: [1] Lewis, S. R. et al., Icarus 192 (2), 327-347, 2007. [2] Rogberg, P. et al., QJRMS 136, 1614-1635, 2010. [3] Greybush, S. J. et al., JGR. 117, E11008, 2012. [4] Ruan, T., DPhil Thesis, 2015. [5] Navarro T. et al., Earth and Space Sci., 2017. [6] Forget, F. et al., JGR 104, 24155-24175, 1999. [7] Madeleine, J.-B. et al., JGR (Planets) 116, E11010, 2011. [8] Newman, C. E. et al., JGR 107, 5123, 2002. [9] Lorenc, A. C. et al., QJRMS 117, 59-89, 1991. [10] Lewis, S. R. et al., Icarus 192, 327-347, 2007. [11] McCleese, D. J. et al., J. Geophys. Res. 115, E12016, 2010. [12] Kleinböhl, A. et al., J. Quant. Spectrosc. Radiat. Transfer 187, 511-522, 2017. [13] Patel, M. R. et al., Appl. Opt. 56 (10), 2771-2782, 2017. [14] Navarro, T. et al., Geophys. Res. Lett. 41, 6620-6626, 2014. [15] Streeter, P. M. et al., 6th Intl. Workshop on the Mars Atmosphere, 2017. [16] Kleinböhl, A. et al., Icarus 261, 118-121, 2015

Homology and Robustness of Level and Interlevel Sets

Given a function f: \Xspace \to \Rspace on a topological space, we consider the preimages of intervals and their homology groups and show how to read the ranks of these groups from the extended persistence diagram of $f$. In addition, we quantify the robustness of the homology classes under perturbations of $f$ using well groups, and we show how to read the ranks of these groups from the same extended persistence diagram. The special case \Xspace = \Rspace^3 has ramifications in the fields of medical imaging and scientific visualization

Migrating agile methods to standardized development practice

Situated process and quality frame-works offer a way to resolve the tensions that arise when introducing agile methods into standardized software development engineering. For these to be successful, however, organizations must grasp the opportunity to reintegrate software development management, theory, and practice

Clinical correlates of blood-derived circulating tumor DNA in pancreatic cancer.

BackgroundTreatment outcomes for patients with advanced pancreatic ductal adenocarcinoma (PDAC) remain dismal. There are unmet needs for understanding the biologic basis of this malignancy using novel next-generation sequencing technologies. Herein, we investigated the clinical utility of circulating tumor DNA (ctDNA) (the liquid biopsy) in this malignancy.MethodsctDNA was analyzed in 112 patients with PDAC (54-73 genes) and tissue DNA in 66 patients (315 genes) (both clinical-grade next-generation sequencing). Number of alterations, %ctDNA, concordance between ctDNA and tissue DNA, and correlation of ctDNA results with survival were assessed.ResultsThe most common genes altered in ctDNA were TP53 (46% of patients, N = 51) and KRAS (44%, N = 49). Median number of characterized ctDNA alterations per patient was 1 (range, 0-6), but patients with advanced PDAC had significantly higher numbers of ctDNA alterations than those with surgically resectable disease (median, 2 versus 0.5, P = 0.04). Overall, 75% (70/94) of advanced tumors had ≥ 1 ctDNA alteration. Concordance rate between ctDNA and tissue DNA alterations was 61% for TP53 and 52% for KRAS. Concordance for KRAS alterations between ctDNA and tissue DNA from metastatic sites was significantly higher than between ctDNA and primary tumor DNA (72% vs 39%, P = 0.01). Importantly, higher levels of total %ctDNA were an independent prognostic factor for worse survival (hazard ratio, 4.35; 95% confidence interval, 1.85-10.24 [multivariate, P = 0.001]). A patient with three ctDNA alterations affecting the MEK pathway (GNAS, KRAS, and NF1) attained a response to trametinib monotherapy ongoing at 6 months.ConclusionsOur findings showed that ctDNA often harbored unique alterations some of which may be targetable and that significantly greater numbers of ctDNA alterations occur in advanced versus resectable disease. Furthermore, higher ctDNA levels were a poor prognostic factor for survival

Adult Onset Still's Disease and Rocky Mountain Spotted Fever

Adult Still's Disease was first described in 1971 by Bywaters in fourteen adult female patients who presented with symptoms indistinguishable from that of classic childhood Still's Disease (Bywaters, 1971). George Still in 1896 first recognized this triad of quotidian (daily) fevers, evanescent rash, and arthritis in children with what later became known as juvenile inflammatory arthritis (Still, 1990). Adult Onset Still's Disease (AOSD) is an inflammatory condition of unknown etiology characterized by an evanescent rash, quotidian fevers, and arthralgias. Numerous infectious agents have been associated with its presentation. This case is to our knowledge the first presentation of AOSD in the setting of Rocky Mountain Spotted Fever. Although numerous infectious agents have been suggested, the etiology of this disorder remains elusive. Nevertheless, infection may in fact play a role in triggering the onset of symptoms in those with this disorder. Our case presentation is, to our knowledge, the first case of Adult Onset Still's Disease associated with Rocky Mountain spotted fever (RMSF)

Psychosocial Effects of a Holistic Ayurvedic Approach to Well-being in Health and Wellness Courses.

BackgroundAs individuals are increasingly attending health and wellness courses outside of the conventional medical system, there is a need to obtain objective data on the effects of those programs on well-being.MethodsIn total, 154 men and women (mean age 54.7 years; range 25-83) participated in 3 different holistic wellness programs based on Ayurvedic Medicine principles (Seduction of Spirit, Journey into Healing, and Perfect Health) or a vacation control group. Psychosocial outcomes included spirituality (Delaney Spirituality Scale), mindful awareness (Mindful Attention Awareness Scale), psychological flexibility (Acceptance and Action Questionnaire), mood (Center for Epidemiology Studies-Depression), and anxiety (Patient-Reported Outcomes Measurement System Anxiety Scale).ResultsParticipants in the Seduction of Spirit (P < .004), Journey into Healing (P < .05), and Perfect Health (P < .004) courses showed significant increases in spirituality as compared to vacation controls. Participants in Seduction of Spirit (P < .007) also showed significant increases in mindfulness as compared to vacation controls. Participants in the Seduction of Spirit (P < .001) and Journey into Healing (P < .05) courses showed significant decreases in depressed mood as compared to those in the Perfect Health and vacation control groups. All study participants showed similar increases in psychological flexibility (P < .01) and decreases in anxiety (P < .01).ConclusionParticipation in wellness courses that incorporate a mind-body-spirit approach to health improves multiple domains of psychosocial well-being, which persists even after course participation

Intramolecular Azide to Alkene Cycloadditions for the Construction of Pyrrolobenzodiazepines and Azetidino-Benzodiazepines

The coupling of proline- and azetidinone-substituted alkenes to 2-azidobenzoic and 2-azidobenzenesulfonic acid gives precursors that undergo intramolecular azide to alkene 1,3-dipolar cycloadditions to give imine-, triazoline- or aziridine-containing pyrrolo[1,4]benzodiazepines (PBDs), pyrrolo[1,2,5]benzothiadiazepines (PBTDs), and azetidino[1,4]benzodiazepines. The imines and aziridines are formed after loss of nitrogen from a triazoline cycloadduct. The PBDs are a potent class of antitumour antibiotics