Direct massively parallel sequencing of SARS-CoV-2 genome was undertaken from nasopharyngeal and oropharyngeal swab samples of infected individuals in Eastern India. Seven of the isolates belonged to the A2a clade, while one belonged to the B4 clade. Specific mutations, characteristic of the A2a clade, were also detected, which included the P323L in RNA-dependent RNA polymerase and D614G in the Spike glycoprotein. Further, our data revealed emergence of novel subclones harbouring nonsynonymous mutations, viz. G1124V in Spike (S) protein, R203K, and G204R in the nucleocapsid (N) protein. The N protein mutations reside in the SR-rich region involved in viral capsid formation and the S protein mutation is in the S 2 domain, which is involved in triggering viral fusion with the host cell membrane. Interesting correlation was observed between these mutations and travel or contact history of COVID-19 positive cases. Consequent alterations of miRNA binding and structure were also predicted for these mutations. More importantly, the possible implications of mutation D614G (in S D domain) and G1124V (in S 2 subunit) on the structural stability of S protein have also been discussed. Results report for the first time a bird's eye view on the accumulation of mutations in SARS-CoV-2 genome in Eastern India.
The braneworld description of our universe entails a large extra dimension and a fundamental scale of gravity that might be lower by several orders of magnitude compared to the Planck scale. An interesting consequence of the braneworld scenario is in the nature of spherically symmetric vacuum solutions to the brane gravitational field equations which could represent black holes with properties quite distinct compared to ordinary black holes in 4-dimensions. We discuss certain key features of some braneworld black hole geometries. Such black holes are likely to have diverse cosmological and astrophysical ramifications. The cosmological evolution of primordial braneworld black holes is described highlighting their longevity due to modified evaporation and effective accretion of radiation during the early braneworld high energy era. Observational abundance of various evaporation products of the black holes at different eras impose constraints on their initial mass fraction. Surviving primordial black holes could be candidates of dark matter present in galactic haloes. We discuss gravitational lensing by braneworld black holes. Observables related to the relativistic images of strong field gravitational lensing could in principle be used to distinguish between different braneworld black hole metrics in future observations.
Abstract:We address the recently posed question as to whether the nonlocality of a single member of an entangled pair of spin 1/2 particles can be shared among multiple observers on the other wing who act sequentially and independently of each other. We first show that the optimality condition for the trade-off between information gain and disturbance in the context of weak or non-ideal measurements emerges naturally when one employs a one-parameter class of positive operator valued measures (POVMs). Using this formalism we then prove analytically that it is impossible to obtain violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality by more than two Bobs in one of the two wings using unbiased input settings with an Alice in the other wing.
We derive a new steering inequality based on a fine-grained uncertainty relation to capture EPRsteering for bipartite systems. Our steering inequality improves over previously known ones since it can experimentally detect all steerable two-qubit Werner state with only two measurement settings on each side. According to our inequality, pure entangle states are maximally steerable. Moreover, by slightly changing the setting, we can express the amount of violation of our inequality as a function of their violation of the CHSH inequality. Finally, we prove that the amount of violation of our steering inequality is, up to a constant factor, a lower bound on the key rate of a one-sided device independent quantum key distribution protocol secure against individual attacks. To show this result, we first derive a monogamy relation for our steering inequality. The development of quantum information led to distinguish three forms of non-local correlations in quantum physics [1][2][3][4][5][6]. These are entanglement, steering and Bell non-local correlations. Einstein, Podolsky and Rosen (EPR) introduced entangled quantum states in an attempt to show the incompleteness of quantum physics known as the EPR paradox [1]. The same year, Schrödinger re-expressed the EPR paradox as the possibility of steering (more generally, known as EPRsteering), i.e., when Alice and Bob share an entangled state, Alice can affect Bob's state throught her own measurement. More precisely, a state exhibits EPR-steering if it cannot be modeled as Bob holding an unknown yet definite state, a description known as a local hidden state (LHS) model [4]. Bell-type inequalities can be used to rule out local hidden variable (LHV) models. Similarly, steering inequalities are used to rule out the existence of LHS model and thus, demonstrate steerability.According to Wiseman, Jones and Doherty, the three forms of non-local correlations are also tightly related to the experimental settings required to test them [4]. To test entanglement, both parties need to trust that they perform quantum operations and also trust their measurement devices. In the case of EPR-steering, only one party assumes that he applies a quantum measurement and that his device is not controlled by a third party. Finally, Bell non-locality can be be tested without assuming quantum theory and trusting measurement devices. This leads to a hierarchy in which EPR-steering lies between Bell non-locality and entanglement.Experimental demonstration of Bell's non-locality has been achieved by several experiments [7]. To test EPRsteering, Reid proposed a testable formulation for continuous variable systems based on the position-momentum uncertainty relation [5]. Denote (X, P x ) and (Y, P y ) the position and corresponding momentum of two correlated modes. According to the Reid criterion, one needs to infer the uncertainty (measured by the standard deviation) of the quadrature amplitude X θk = cos[θk]X + sin[θk]P x for k ∈ {1, 2} from the measurement outcome of the correlated amplitude Y φk = cos[φ...
Quantum mechanics puts a restriction on the number of observers who can simultaneously steer another observer's system, known as the monogamy of steering. In this work we find the limit of the number of observers (Bobs) who can steer another party's (Alice's) system invoking a scenario where half of an entangled pair is shared between a single Alice in one wing and several Bobs on the other wing, who act sequentially and independently of each other. When all the observers measure two dichotomic observables, we find that two Bobs can steer Alice's system going beyond the monogamy restriction. We further show that three Bobs can steer Alice's system considering a three-settings linear steering inequality, and then conjecture that at most n Bobs can demonstrate steering of Alice's system when steering is probed through an n-settings linear steering inequality.
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