Nearly optimal time-independent reversal of a spin chain

We propose a time-independent Hamiltonian protocol for the reversal of qubit ordering in a chain of $N$ spins. Our protocol has an easily implementable nearest-neighbor, transverse-field Ising model Hamiltonian with time-independent, non-uniform couplings. Under appropriate normalization, we implement this state reversal three times faster than a naive approach using SWAP gates, in time comparable to a protocol of Raussendorf [Phys. Rev. A 72, 052301 (2005)] that requires dynamical control. We also prove lower bounds on state reversal by using results on the entanglement capacity of Hamiltonians and show that we are within a factor $1.502(1+1/N)$ of the shortest time possible. Our lower bound holds for all nearest-neighbor qubit protocols with arbitrary finite ancilla spaces and local operations and classical communication. Finally, we extend our protocol to an infinite family of nearest-neighbor, time-independent Hamiltonian protocols for state reversal. This includes chains with nearly uniform coupling that may be especially feasible for experimental implementation.Comment: 7 pages, 2 figure

Hierarchical amino acid utilization and its influence on fermentation dynamics: rifamycin B fermentation using Amycolatopsis mediterranei S699, a case study

BACKGROUND: Industrial fermentation typically uses complex nitrogen substrates which consist of mixture of amino acids. The uptake of amino acids is known to be mediated by several amino acid transporters with certain preferences. However, models to predict this preferential uptake are not available. We present the stoichiometry for the utilization of amino acids as a sole carbon and nitrogen substrate or along with glucose as an additional carbon source. In the former case, the excess nitrogen provided by the amino acids is excreted by the organism in the form of ammonia. We have developed a cybernetic model to predict the sequence and kinetics of uptake of amino acids. The model is based on the assumption that the growth on a specific substrate is dependent on key enzyme(s) responsible for the uptake and assimilation of the substrates. These enzymes may be regulated by mechanisms of nitrogen catabolite repression. The model hypothesizes that the organism is an optimal strategist and invests resources for the uptake of a substrate that are proportional to the returns. RESULTS: Stoichiometric coefficients and kinetic parameters of the model were estimated experimentally for Amycolatopsis mediterranei S699, a rifamycin B overproducer. The model was then used to predict the uptake kinetics in a medium containing cas amino acids. In contrast to the other amino acids, the uptake of proline was not affected by the carbon or nitrogen catabolite repression in this strain. The model accurately predicted simultaneous uptake of amino acids at low cas concentrations and sequential uptake at high cas concentrations. The simulated profile of the key enzymes implies the presence of specific transporters for small groups of amino acids. CONCLUSION: The work demonstrates utility of the cybernetic model in predicting the sequence and kinetics of amino acid uptake in a case study involving Amycolatopsis mediterranei, an industrially important organism. This work also throws some light on amino acid transporters and their regulation in A. mediterranei .Further, cybernetic model based experimental strategy unravels formation and utilization of ammonia as well as its inhibitory role during amino acid uptake. Our results have implications for model based optimization and monitoring of other industrial fermentation processes involving complex nitrogen substrate

The Association between Educational Achievements, Career Aspirations, Achievement Motives and Oral Hygiene Behavior among Dental Students of Udaipur, India

Background: There are several factors which influence oral hygiene behavior of an individual. Educational achievements, career aspirations and achievement motives of individuals are some of those factors. The objective of this study was to investigate whether educational achievements, career aspirations and achievement motives have associations with oral hygiene behavior among dental students of Udaipur, India.Methods: A descriptive cross-sectional study was conducted among all (n=200) 1st year dental students from all dental colleges of Udaipur City, India. Self-administered structured questions were used to assess their educational achievements, career aspirations and oral hygiene behavior (OHB). Achievement motives were assessed using Achievement Motive Scale developed by Lang and Fries (2006). Chi-square test and multivariate logistic regression tests were used in data analysis. Confidence level and level of significance were set at 95% and 5% respectively.Results: Students with better educational achievements undergone regular dental check-up (30.48%) (p=0.03) and used other oral hygiene aids (90.24%) (p=0.01). Tooth brushing frequency, time and replacement time of tooth brush were found to be significantly associated with career aspiration (p=0.007; p=0.002; p=0.00 respectively). Achievement motives did not have statistically significant association with oral hygiene behavior.Conclusion: Educational achievements and career aspirations appear to be associated with oral hygiene behavior of young dental students. Students with higher career aspirations practiced better oral hygiene behavior. There was no significant relationship between achievement motives and oral hygiene behavior.Keywords: Educational achievements, career aspirations, achievement motives, oral hygiene

Penning Spectroscopy and Structure of Acetylene Oligomers in He Nanodroplets

Embedded atoms or molecules in a photoexcited He nanodroplet are well-known to be ionized through inter-atomic relaxation in a Penning process. In this work, we investigate the Penning ionization of acetylene oligomers occurring from the photoexcitation bands of He nanodroplets. In close analogy to conventional Penning electron spectroscopy by thermal atomic collisions, the n = 2 photoexcitation band plays the role of the metastable atomic $1s2s$ $^{3,1}S$ He$^\ast$. This facilitates electron spectroscopy of acetylene aggregates in the sub-kelvin He environment, providing the following insight into their structure: The molecules in the dopant cluster are loosely bound van der Waals complexes rather than forming covalent compounds. In addition, this work reveals a Penning process stemming from the n = 4 band where charge-transfer from autoionized He in the droplets is known to be the dominant relaxation channel. This allows for excited states of the remnant dopant oligomer Penning-ions to be studied. Hence, we demonstrate Penning ionization electron spectroscopy of doped droplets as an effective technique for investigating dopant oligomers which are easily formed by attachment to the host cluster.Comment: 22 pages, 1 png figure, 4 postscript figure

Null cone preserving maps, causal tensors and algebraic Rainich theory

A rank-n tensor on a Lorentzian manifold V whose contraction with n arbitrary causal future directed vectors is non-negative is said to have the dominant property. These tensors, up to sign, are called causal tensors, and we determine their general properties in dimension N. We prove that rank-2 tensors which map the null cone on itself are causal. It is known that, to any tensor A on V there is a corresponding ``superenergy'' (s-e) tensor T{A} which always has the dominant property. We prove that, conversely, any symmetric rank-2 tensor with the dominant property can be written in a canonical way as a sum of N s-e tensors of simple forms. We show that the square of any rank-2 s-e tensor is proportional to the metric if N<5, and that this holds for the s-e tensor of any simple form for arbitrary N. Conversely, we prove that any symmetric rank-2 tensor T whose square is proportional to the metric must be, up to sign, the s-e of a simple p-form, and that the trace of T determines the rank p of the form. This generalises, both with respect to N and the rank p, the classical algebraic Rainich conditions, which are necessary and sufficient conditions for a metric to originate in some physical field, and has a geometric interpretation: the set of s-e tensors of simple forms is precisely the set of tensors which preserve the null cone and its time orientation. It also means that all involutory Lorentz transformations (LT) can be represented as s-e tensors of simple forms, and that any rank-2 s-e tensor is the sum of at most N conformally involutory LT. Non-symmetric null cone preserving maps are shown to have a causal symmetric part and are classified according to the null eigenvectors of the skew-symmetric part. We thus obtain a complete classification of all conformal LT and singular null cone preserving maps on V.Comment: 36 pages, no figures, LaTeX fil

Fishery resources of the Exclusive Economic Zone of the northwest coast of India

For well over two decades now, trawling operations, both exploratory and commercial, have been going on along the north-western region, off the Goa, Maha rashtra and Gujarat coasts (15°-24°N). A historical resimie of trawling in India has been given by Jayaraman et al. (1959) in their account of the demersal fishery resources of the shelf waters of this area, for the period 1950 to 1955. Similar accoimts on the distribution patterns of major exploited fisheries for 1961-1967 and 1968-1970, have been given by Rao (1969) and Rao et al. (1966, 1972) and Nair (1974). Apart from the above accoimts on the fisheries in general, detailed studies on the pattern of distribution and abundance of individual species have been reported by Rao (1965— Pseudosciaena' diacanthus), Kagwade (1973—Polynemus heptadactylus), Deshmukh (1973—Pomadasys hasta), Kaikini (1974—Lactarius lactarius) and Kagwade {1966—prawns), as also (Prabhu and Dhawan, 1974)— regional fisheries off Goa. The results of these studies, based on bottom-trawling operations mostly in regions less than 80 metres in depth, have given us a fair knowledge of the demersal resources potential of this region

A rigid barrier between the heart and sternum protects the heart and lungs against rupture during negative pressure wound therapy

<p>Abstract</p> <p>Objectives</p> <p>Right ventricular heart rupture is a devastating complication associated with negative pressure wound therapy (NPWT) in cardiac surgery. The use of a rigid barrier has been suggested to offer protection against this lethal complication, by preventing the heart from being drawn up and damaged by the sharp edges of the sternum. The aim of the present study was to investigate whether a rigid barrier protects the heart and lungs against injury during NPWT.</p> <p>Methods</p> <p>Sixteen pigs underwent median sternotomy followed by NPWT at -120 mmHg for 24 hours, in the absence (eight pigs) or presence (eight pigs) of a rigid plastic disc between the heart and the sternal edges. The macroscopic appearance of the heart and lungs was inspected after 12 and 24 hours of NPWT.</p> <p>Results</p> <p>After 24 hours of NPWT at -120 mmHg the area of epicardial petechial bleeding was 11.90 ± 1.10 cm²when no protective disc was used, and 1.15 ± 0.19 cm²when using the disc (p < 0.001). Heart rupture was observed in three of the eight animals treated with NPWT without the disc. Lung rupture was observed in two of the animals, and lung contusion and emphysema were seen in all animals treated with NPWT without the rigid disc. No injury to the heart or lungs was observed in the group of animals treated with NPWT using the rigid disc.</p> <p>Conclusion</p> <p>Inserting a rigid barrier between the heart and the sternum edges offers protection against heart rupture and lung injury during NPWT.</p