SARAS 2 Constraints on Global 21 cm Signals from the Epoch of Reionization

Spectral distortions in the cosmic microwave background over the 40--200~MHz band are imprinted by neutral hydrogen in the intergalactic medium prior to the end of reionization. This signal, produced in the redshift range $z = 6-34$ at the rest frame wavelength of 21 cm, has not been detected yet; and poor understanding of high redshift astrophysics results in a large uncertainty in the expected spectrum. The SARAS~2 radiometer was purposely designed to detect the sky-averaged 21-cm signal. The instrument, deployed at the Timbaktu Collective (Southern India) in April--June 2017, collected 63~hr of science data, which were examined for the presence of the cosmological 21-cm signal. In our previous work the first-light data from SARAS~2 radiometer were analyzed with Bayesian likelihood-ratio tests using $264$ plausible astrophysical scenarios. In this paper we re-examine the data using an improved analysis based on the frequentist approach and forward modeling. We show that SARAS~2 data rejects 27 models, out of which 25 are rejected at a significance $>5\sigma$. All the rejected models share the scenario of inefficient heating of the primordial gas by the first population of X-ray sources along with rapid reionization

First Results on the Epoch of Reionization from First Light with SARAS 2

Long wavelength spectral distortions in the Cosmic Microwave Background arising from the 21-cm transition in neutral Hydrogen are a key probe of Cosmic Dawn and the Epoch of Reionization. These features may reveal the nature of the first stars and ultra-faint galaxies that transformed the spin temperature and ionization state of the primordial gas. SARAS~2 is a spectral radiometer purposely designed for precision measurement of these monopole or all-sky global 21-cm spectral distortions. We use 63~hr night time observing of the radio background in the frequency band 110-200~MHz with the radiometer deployed at the Timbaktu Collective in Southern India to derive likelihoods for plausible redshifted 21-cm signals predicted by theoretical models. First light with SARAS 2 disfavors the class of models that feature weak X-ray heating (with $f_X \leq 0.1$) and rapid reionization (with peak $\frac{dT_b}{dz} \geq 120~\textrm{mK per unit redshift interval}$ )

Crystal, Solution and In silico Structural Studies of Dihydrodipicolinate Synthase from the Common Grapevine

Dihydrodipicolinate synthase (DHDPS) catalyzes the rate limiting step in lysine biosynthesis in bacteria and plants. The structure of DHDPS has been determined from several bacterial species and shown in most cases to form a homotetramer or dimer of dimers. However, only one plant DHDPS structure has been determined to date from the wild tobacco species, Nicotiana sylvestris (Blickling et al. (1997) J. Mol. Biol. 274, 608–621). Whilst N. sylvestris DHDPS also forms a homotetramer, the plant enzyme adopts a ‘back-to-back’ dimer of dimers compared to the ‘head-to-head’ architecture observed for bacterial DHDPS tetramers. This raises the question of whether the alternative quaternary architecture observed for N. sylvestris DHDPS is common to all plant DHDPS enzymes. Here, we describe the structure of DHDPS from the grapevine plant, Vitis vinifera, and show using analytical ultracentrifugation, small-angle X-ray scattering and X-ray crystallography that V. vinifera DHDPS forms a ‘back-to-back’ homotetramer, consistent with N. sylvestris DHDPS. This study is the first to demonstrate using both crystal and solution state measurements that DHDPS from the grapevine plant adopts an alternative tetrameric architecture to the bacterial form, which is important for optimizing protein dynamics as suggested by molecular dynamics simulations reported in this study

Progressive hemorrhage and myotoxicity induced by echis carinatus venom in murine model: neutralization by inhibitor cocktail of n,n,n `,n `-tetrakis (2-pyridylmethyl) ethane-1,2-diamine and silymarin

Viperbite is often associated with severe local toxicity, including progressive hemorrhage and myotoxicity, persistent even after the administration of anti-snake venom (ASV). In the recent past, investigations have revealed the orchestrated actions of Zn2+ metalloproteases (Zn(2+)MPs), phospholipase A(2)s (PLA(2)s) and hyaluronidases (HYs) in the onset and progression of local toxicity from the bitten site. As a consequence, venom researchers and medical practitioners are in deliberate quest of potent molecules alongside ASV to tackle the brutal local manifestations induced by aforesaid venom toxins. Based on these facts, we have demonstrated the protective efficacy of inhibitor cocktail containing equal ratios of N,N,N', N'-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and silymarin (SLN) against progressive local toxicity induced by Echis carinatus venom (ECV). In our previous study we have shown the inhibitory potentials of TPEN towards Zn(2+)MPs of ECV (IC50: 6.7 mu M). In this study we have evaluated in vitro inhibitory potentials of SLN towards PLA(2)s (IC50: 12.5 mu M) and HYs (IC50: 8 mu M) of ECV in addition to docking studies. Further, we have demonstrated the protection of ECV induced local toxicity with 10 mM inhibitor cocktail following 15, 30 min (for hemorrhage and myotoxicity); 60 min (for hemorrhage alone) of ECV injection in murine model. The histological examination of skin and thigh muscle sections taken out from the site of ECV injection substantiated the overall protection offered by inhibitor cocktail. In conclusion, the protective efficacy of inhibitor cocktail is of high interest and can be administered locally alongside ASV to treat severe local toxicity

Outcomes of First Metatarsophalangeal Joint Fusion in Patients with Greater Than Fifteen Percent Intermetatarsal Angle. Is Lag Screw Essential?

Category: Midfoot/Forefoot Introduction/Purpose: Metatarsophalangeal arthrodesis has usually been performed using a dorsal plate to immobilize the MTP joint with or without lag screw fixation. Data in the literature is sparse on outcomes of dorsal plate plus lag screw fixation, especially in patients with IMA greater than 15 percent. Our objective was to compare IMA correction outcomes and union rates between dorsal plate only fusions and dorsal plate plus lag screw fixation in patients with IMA greater than 15 percent. Methods: We retrospectively reviewed the charts of 36 patients (39 feet) who underwent first MTP joint arthrodesis for moderate to severe HV deformity between 2011 and 2015. Average age was 61 (range, 39 to 84) years. There were 24 females and 12 males. A single surgeon performed all operations. Joints were immobilized postoperatively using either dorsal locking plate alone or dorsal locking plate with a lag screw. Union (at least 3 bridging cortices) was determined radiographically at 6 weeks, 3 months, 6 months and yearly. All suspect nonunions were examined with CT. Other radiographic parameters examined included preoperative and postoperative hallux valgus, intermetatarsal, and dorsiflexion angles (HVA, IMA, and DFA respectively). Student’s t test was used to compare group means while Pearson’s Chi square test was used to compare group rates. Results: Overall union rate was 82.1% (32/39). There was no significant difference in union rates between the two groups (dorsal plate only = 81.5% (22/27), dorsal plate plus lag screw group = 83.3% (10/12)) (P > 0.05). Average follow-up was 9 (range 7 to 35) months. Overall, the average IMA correction was 4.7 (preoperative = 17.8, postoperative = 13.1) degrees. Average IMA corrections were 4.7 and 4.54 degrees in the dorsal plate only group and dorsal plate plus lag screw groups respectively. Overall, average HVA correction was 21 (preoperative = 39.5, postoperative = 18.5) degrees. Conclusion: Our findings indicate that there is no difference in the fusion rates between both patient groups with IMA greater than fifteen percent. Because other published studies have a wide range of IMAs preoperatively, our study represents more attainable goals in patients with severe (IMA greater than 15%) deformities. In addition, our findings suggest that in such patients, MTP arthrodesis may not be sufficient as a standalone procedure for correction of IMA. Additional proximal osteotomy may be required for correction of the IMA