Reconstructing river flows remotely on Earth, Titan, and Mars.

Alluvial rivers are conveyor belts of fluid and sediment that provide a record of upstream climate and erosion on Earth, Titan, and Mars. However, many of Earth's rivers remain unsurveyed, Titan's rivers are not well resolved by current spacecraft data, and Mars' rivers are no longer active, hindering reconstructions of planetary surface conditions. To overcome these problems, we use dimensionless hydraulic geometry relations-scaling laws that relate river channel dimensions to flow and sediment transport rates-to calculate in-channel conditions using only remote sensing measurements of channel width and slope. On Earth, this offers a way to predict flow and sediment flux in rivers that lack field measurements and shows that the distinct dynamics of bedload-dominated, suspended load-dominated, and bedrock rivers give rise to distinct channel characteristics. On Mars, this approach not only predicts grain sizes at Gale Crater and Jezero Crater that overlap with those measured by the Curiosity and Perseverance rovers, it enables reconstructions of past flow conditions that are consistent with proposed long-lived hydrologic activity at both craters. On Titan, our predicted sediment fluxes to the coast of Ontario Lacus could build the lake's river delta in as little as ~1,000 y, and our scaling relationships suggest that Titan's rivers may be wider, slope more gently, and transport sediment at lower flows than rivers on Earth or Mars. Our approach provides a template for predicting channel properties remotely for alluvial rivers across Earth, along with interpreting spacecraft observations of rivers on Titan and Mars.

Familial Dilated Cardiomyopathy.

Advances in human genome sequencing have re-invigorated genetics studies of dilated cardiomyopathy (DCM), facilitating genetic testing and clinical applications. With a range of genetic testing options now available, new challenges arise for data interpretation and identifying single pathogenic variants from the many thousands of rare variants present in every individual. There is accumulating evidence that genetic factors have an important role in the pathogenesis of DCM. However, although more than 100 genes have been implicated to date, the sensitivity of genetic testing, even in familial disease, is only ∼25-40%. As more patients are genotyped, nuanced information about disease phenotypes is emerging including variability in age of onset and penetrance of DCM, as well as additional cardiac and extra-cardiac features. Genotype-phenotype correlations have also identified a subset of genes that can be highly arrhythmogenic or show frequent progression to heart failure. Recognition of variants in these genes is important as this may impact on the timing of implantable cardioverter-defibrillators or heart transplantation. Finding a causative variant in a patient with DCM allows predictive testing of family members and provides an opportunity for preventative intervention. Diagnostic imaging modalities such as speckle-tracking echocardiography and cardiac magnetic resonance imaging are increasingly being used to detect and monitor pre-clinical ventricular dysfunction in asymptomatic variant carriers. Although there are several examples of successful genotype-based therapy, optimal strategies for implementation of precision medicine in familial DCM remain to be determined. Identification of modifiable co-morbidities and lifestyle factors that exacerbate or protect against DCM development in genetically-predisposed individuals remains a key component of family management.

Cardio-oncology and radiation oncology: How collaboration between cardiologists and oncologists can be realised in radiation oncology.

Increased survivorship, improvements in cancer treatments, and the potential for cardiac side effects from cancer treatments have resulted in increased collaboration between oncologists and cardiologists and the development of cardio-oncology clinics. This collaboration is important given its role in ensuring greater patient satisfaction, aiding teams of clinicians in making complex treatment decision, and ensuring cardiac complications are diagnosed at an early stage. The particularities of implementing this collaboration in the field of radiation oncology and how this setting is different from other areas of cardio-oncology have not been well detailed in the literature. This paper will discuss what is currently understood about the need for and role of cardio-oncology and what a cardio-oncology services involves, with a particular emphasis on patient and clinician needs in the field of radiation oncology. The literature and recent guidelines do advocate for a detailed baseline assessment of cancer patients undergoing radiotherapy, especially patients with treatment or patient risk factors that increase their risk of cancer-therapy related cardiotoxicity. Advancements in cardiac imaging techniques will be discussed as these may help to diagnose cardiac side effects of certain cancer treatments, including radiotherapy, at an early stage. A multi-disciplinary and collaborative approach is well received by patients and such an approach, guided by the aim of maintaining a patient's cancer treatment wherever possible, should be the cornerstone of cardio-oncology clinics regardless of the patient's treatment regime.

Signatures of wave erosion in Titan's coasts.

The shorelines of Titan's hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it is unclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theoretical models suggest that wind may cause waves to form on Titan's seas, potentially driving coastal erosion, but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titan remain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively discern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combine landscape evolution models with measurements of shoreline shape on Earth to characterize how different coastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that the shorelines of Titan's seas are most consistent with flooded landscapes that subsequently have been eroded by waves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates at fetch lengths of tens of kilometers.

The dead donor rule: a defense.

Miller, Truog, and Brock have recently argued that the "dead donor rule," the requirement that donors be determined to be dead before vital organs are procured for transplantation, cannot withstand ethical scrutiny. In their view, the dead donor rule is inconsistent with existing life-saving practices of organ transplantation, lacks a cogent ethical rationale, and is not necessary for maintenance of public trust in organ transplantation. In this paper, the second of these claims will be evaluated. (The first and third are not addressed.) The claim that the dead donor rule lacks a cogent ethical rationale will be shown to be an expression of the contemporary rejection of the moral significance of the traditional distinction between killing and allowing to die. The moral significance of this traditional distinction, and the associated norm that doctors should not kill their patients, will be defended, and this critique of it shown to be unsuccessful.

Cardiovascular magnetic resonance imaging for structural heart disease.

Cardiovascular magnetic resonance (CMR) has increasingly become a powerful imaging technique over the past few decades due to increasing knowledge about clinical applications, operator experience and technological advances, including the introduction of high field strength magnets, leading to improved signal-to-noise ratio. Its success is attributed to the free choice of imaging planes, the wide variety of imaging techniques, and the lack of harmful radiation. Developments in CMR have led to the accurate evaluation of cardiac structure, function and tissues characterisation, so this non-invasive technique has become a powerful tool for a broad range of cardiac pathologies. This review will provide an introduction of magnetic resonance imaging (MRI) physics, an overview of the current techniques and clinical application of CMR in structural heart disease, and illustrated examples of its use in clinical practice.

The root of anomalously specular reflections from solid surfaces on Saturn's moon Titan.

Saturn's moon Titan has a methane cycle with clouds, rain, rivers, lakes, and seas; it is the only world known to presently have a volatile cycle akin to Earth's tropospheric water cycle. Anomalously specular radar reflections (ASRR) from Titan's tropical region were observed with the Arecibo Observatory (AO) and Green Bank Telescope (GBT) and interpreted as evidence for liquid surfaces. The Cassini spacecraft discovered lakes/seas on Titan, however, it did not observe lakes/seas at the AO/GBT anomalously specular locations. A satisfactory explanation for the ASRR has been elusive for more than a decade. Here we show that the ASRR originate from one terrain unit, likely paleolakes/paleoseas. Titan observations provide ground-truth in the search for oceans on exoearths and an important lesson is that identifying liquid surfaces by specular reflections requires a stringent definition of specular; we propose a definition for this purpose.

Ergometrine-induced atrial fibrillation at caesarean section.

A 36-year-old woman with a history of one previous caesarean section presented to the birthing suite of a regional hospital with spontaneous rupture of membranes at 39+2/40 weeks. Syntocinon was administered to initiate uterine contractions in the absence of labour, as the patient desired vaginal birth. A caesarean section was subsequently indicated and ergometrine was administered for uterine atony. The patient immediately developed atrial fibrillation (AF). AF is the most common sustained arrhythmia in the general population, but is rare in the obstetric population. AF occurring in an intrapartum setting following the administration of syntocinon and ergometrine, is not documented in the literature. We suggest the initiation of paroxysmal AF was precipitated by an abrupt alteration in autonomic tone caused by administration of syntocinon followed by ergometrine.

Chorioamnionitis and cerebral palsy: a meta-analysis.

OBJECTIVE: To examine the relationships between clinical or histological chorioamnionitis and cerebral palsy using a meta-analysis approach. DATA SOURCES: A systematic review of the literature appeared in PubMed between 2000 and 2009 was conducted using the search terms "cerebral palsy" and "infection," with broad-scope variations in terminology of "white matter damage," "periventricular leukomalacia," "cystic periventricular leukomalacia," "chorioamnionitis," "intrauterine infection," "intraventricular hemorrhage," "funisitis," "fetal inflammatory response," "early neonatal sepsis," "neurological impairment," "virus," "bacteria," "fungi," and "protozoa," with variations of suffixes (eg, "viral," "bacterial," "fungal," "protozoan," etc), and "urinary tract infection," "bacterial vaginosis," "bacteriuria," and "cytokines." The related key words "gestational age," "small for gestational age," "preterm," and "low birth weight" also were added to the search terms. Only studies published in English were included. METHODS: Three hundred eight articles were retrieved and systematically reviewed independently by two authors. Application of four inclusion criteria led to 15 studies being considered for data abstraction. An exposure was considered relevant if it met the established criteria for clinical or histological chorioamnionitis. The outcome was a diagnosis of cerebral palsy in accordance with established criteria. RESULTS: The data were abstracted onto standard forms, correlated according to eight characteristics, and tabulated. Twelve of the 15 studies contained information on the association between clinical chorioamnionitis and cerebral palsy, and eight studies included information on the association between histological chorioamnionitis and cerebral palsy. The results indicated that there were significant associations between clinical chorioamnionitis or histological chorioamnionitis and cerebral palsy, for clinical chorioamnionitis (chi1=13.91; P<.001) with a pooled odds ratio of 2.42 (95% confidence interval 1.52-3.84), and for histological chorioamnionitis (chi1=6.86; P=.009) with a pooled odds ratio of 1.83 (95% confidence interval, 1.17-2.89). The data suggested increased risks of 140% and 80% for neonates exposed to clinical chorioamnionitis or histological chorioamnionitis, respectively. CONCLUSION: The significant association of clinical or histological chorioamnionitis with cerebral palsy suggested that clinical strategies to prevent or reduce chorioamnionitis would lead to a reduction in cerebral palsy. The culture techniques currently used to diagnose the presence of pathogenic microorganisms during pregnancy need to improve, both in their methodology and in the length of time they require.

The structural characteristics of organozinc complexes incorporating N,N'-bidentate ligands.

Dimethylzinc reacts with an excess of N-2-pyridylaniline 6 to give the homoleptic species, Zn[PhN(2-C(5)H(4)N)](2) 8. Single crystal X-ray diffraction reveals a solid-state dimer based on an 8-membered (NCNZn)(2) core motif. Zn[CyN(2-C(5)H(4)N)]Me (Cy =c-C(6)H(11)) 10, prepared by the combination of ZnMe(2) with the corresponding cyclohexyl-substituted pyridylamine, is also dimeric in the solid state but reveals a central (ZnN)(2) metallacycle. Employment of (p-Tol)NH(2-C(5)H(4)N)(p-Tol = 4-MeC(6)H(4)) 11 yielded the tris(zinc) adduct Zn(3)[(p-Tol)N(2-C(5)H(4)N)](4)Me(2) 12, which incorporates a central chiral molecule of 'Zn[(p-Tol)N(2-C(5)H(4)N)](2)' 12a, that bridges two 'Zn[(p-Tol)N(2-C(5)H(4)N)]Me' 12b units. A similar trimetallic structure is noted when the pyridylaniline substrate 11 is replaced with the bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH), affording Zn(3)(hpp)(4)Me(2) 13. Spectroscopic studies point to retention of the solid-state structure of in hydrocarbon solution. Reaction of 13 with dimesityl borinic acid, Mes(2)BOH (Mes = mesityl), affords Zn(3)(hpp)(4)(OBMes(2))(2) 14 in which the trimetallic core is retained. This reactivity is in contrast to the closely related reaction of dimeric Zn[Me(2)NC[N(i)Pr](2)]Me 15 with Mes(2)BOH, which yielded Zn[Me(2)NC[N(i)Pr](2)][OBMes(2)].Me(2)NC[N(i)Pr][NH(i)Pr] 16 as a result of protonation at the guanidine ligand in addition to the Zn-Me bond.