Stellar structure and compact objects before 1940: Towards relativistic astrophysics

Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal

Efficiency Potential and Voltage Loss of Inorganic CsPbI2Br Perovskite Solar Cells

Inorganic perovskite solar cells show excellent thermal stability, but the reported power conversion efficiencies are still lower than for organic inorganic perovskites. This is mainly caused by lower open circuit voltages VOCs . Herein, the reasons for the low VOC in inorganic CsPbI2Br perovskite solar cells are investigated. Intensity dependent photoluminescence measurements for different layer stacks reveal that n i p and p i n CsPbI2Br solar cells exhibit a strong mismatch between quasi Fermi level splitting QFLS and VOC. Specifically, the CsPbI2Br p i n perovskite solar cell has a QFLS e amp; 8201; VOC mismatch of 179 amp; 8201;meV, compared with 11 amp; 8201;meV for a reference cell with an organic inorganic perovskite of similar bandgap. On the other hand, this study shows that the CsPbI2Br films with a bandgap of 1.9 amp; 8201;eV have a very low defect density, resulting in an efficiency potential of 20.3 with a MeO 2PACz hole transporting layer and 20.8 on compact TiO2. Using ultraviolet photoelectron spectroscopy measurements, energy level misalignment is identified as a possible reason for the QFLS e amp; 8201; VOC mismatch and strategies for overcoming this VOC limitation are discussed. This work highlights the need to control the interfacial energetics in inorganic perovskite solar cells, but also gives promise for high efficiencies once this issue is resolve

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Diagnosis of biliary tract and ampullary carcinomas

Diagnostic methods for biliary tract carcinoma and the efficacy of these methods are discussed. Neither definite methods for early diagnosis nor specific markers are available in this disease. When this disease is suspected on the basis of clinical symptoms and risk factors, hemato-biochemical examination and abdominal ultrasonography are performed and, where appropriate, enhanced computed tomography (CT) and/or magnetic resonance cholangiopancreatography (MRCP) is carried out. Diagnoses of extrahepatic bile duct cancer and ampullary carcinoma are often made based on the presence of obstructive jaundice. Although rare, abdominal pain and pyrexia, as well as abnormal findings of the hepatobiliary system detected by hemato-biochemical examination, serve as a clue to making a diagnosis of these diseases. On the other hand, the early diagnosis of gallbladder cancer is scarcely possible on the basis of clinical symptoms, so when this cancer is found with the onset of abdominal pain and jaundice, it is already advanced at the time of detection, thus making a cure difficult. When gallbladder cancer is suspected, enhanced CT is carried out. Multidetector computed tomography (MDCT), in particular — one of the methods of enhanced CT — is useful for decision of surgical criteria, because MDCT shows findings such as localization and extension of the tumor, and the presence or absence of remote metastasis. Procedures such as magnetic resonance imaging, endoscopic ultrasonography, bile duct biopsy, and cholangioscopy should be carried out taking into account indications for these procedures in individual patients. However, direct biliary tract imaging is necessary for making a precise diagnosis of the horizontal extension of bile duct cancer

An international effort towards developing standards for best practices in analysis, interpretation and reporting of clinical genome sequencing results in the CLARITY Challenge

There is tremendous potential for genome sequencing to improve clinical diagnosis and care once it becomes routinely accessible, but this will require formalizing research methods into clinical best practices in the areas of sequence data generation, analysis, interpretation and reporting. The CLARITY Challenge was designed to spur convergence in methods for diagnosing genetic disease starting from clinical case history and genome sequencing data. DNA samples were obtained from three families with heritable genetic disorders and genomic sequence data were donated by sequencing platform vendors. The challenge was to analyze and interpret these data with the goals of identifying disease-causing variants and reporting the findings in a clinically useful format. Participating contestant groups were solicited broadly, and an independent panel of judges evaluated their performance. RESULTS: A total of 30 international groups were engaged. The entries reveal a general convergence of practices on most elements of the analysis and interpretation process. However, even given this commonality of approach, only two groups identified the consensus candidate variants in all disease cases, demonstrating a need for consistent fine-tuning of the generally accepted methods. There was greater diversity of the final clinical report content and in the patient consenting process, demonstrating that these areas require additional exploration and standardization. CONCLUSIONS: The CLARITY Challenge provides a comprehensive assessment of current practices for using genome sequencing to diagnose and report genetic diseases. There is remarkable convergence in bioinformatic techniques, but medical interpretation and reporting are areas that require further development by many groups

Flowcharts for the management of biliary tract and ampullary carcinomas

No strategies for the diagnosis and treatment of biliary tract carcinoma have been clearly described. We developed flowcharts for the diagnosis and treatment of biliary tract carcinoma on the basis of the best clinical evidence. Risk factors for bile duct carcinoma are a dilated type of pancreaticobiliary maljunction (PBM) and primary sclerosing cholangitis. A nondilated type of PBM is a risk factor for gallbladder carcinoma. Symptoms that may indicate biliary tract carcinoma are jaundice and pain in the upper right area of the abdomen. The first step of diagnosis is to carry out blood biochemistry tests and ultrasonography (US) of the abdomen. The second step of diagnosis is to find the local extension of the carcinoma by means of computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), percutaneous transhepatic cholangiography (PTC), and endoscopic retrograde cholangiopancreatography (ERCP). Because resection is the only way to completely cure biliary tract carcinoma, the indications for resection are determined first. In patients with resectable disease, the indications for biliary drainage or portal vein embolization (PVE) are checked. In those with nonresectable disease, biliary stenting, chemotherapy, radiotherapy, and/or best supportive care is selected

Effects of current CO2 assimilation and stored reserves on lychee fruit growth

The roles of current CO2 assimilation and stored carbohydrates on fruit retention in lychee (Litchi chinensis Sonn.) were investigated. In 12 year old ‘Tai So’ trees growing at Burgershall in subtropical South Africa (lat. 25°S), terminal branches were cinctured (girdled) 0.5 or 1.0 m from the fruit cluster about 2–4 weeks after anthesis in October to isolate the fruit from the rest of the tree. Each branch had 0, 5,10, 20 or 30 leaves, and 0, 5,10, 20 or 30 fruit. In a separate experiment, branches were cinctured 0.5 or 1.5 m from the fruit cluster in October, while uncinctured branches acted as controls. At Nambour in subtropical Australia (lat. 27°S), branches of ten year old ‘Souey Tung’ were cinctured in October after fruit set about 1.2 m from the fruit cluster, while other branches were cinctured and thinned to five leaves or five fruit per fruit cluster or left uncinctured and unthinned. In other experiments, seven year old trees of cv. Wai Chee and ten year old trees of cv. Kwai May Pink were cinctured on the trunk in November or left uncinctured. The number of fruit retained per panicle, net CO2 assimilation, yield and concentrations of starch in the leaves and stem were determined. In South Africa, the greatest number of fruit per panicle at harvest (8.6) occurred with 30 leaves and 30 fruit at the start of sampling, but a different response was given when the number of fruit retained was expressed as a proportion of that soon after fruit set. Relative fruit retention was below 5% in branches with no leaves and 50–60% in branches with six leaves per fruit. In Australia, about a quarter of the fruit were retained at harvest in control and cinctured branches compared with more than two-thirds after fruit thinning and only one-tenth after leaf thinning. Starch generally accumulated in the stems after fruit were removed, whereas CO2 assimilation was greatest after leaf removal and least with fruit removal. There was double the relative fruit retention with cinctures at 0.5 m (25%) compared with controls (14%), and three times as many with cinctures at 1.5 m (38%), and a 35% increase in yield when whole trees were cinctured. These results suggest that lychee fruit appear to be mainly dependent on current CO2 assimilation. Cincturing increased yields presumably by redirecting assimilates to the developing crop