ID-based Ring Signature and Proxy Ring Signature Schemes from Bilinear Pairings

In 2001, Rivest et al. firstly introduced the concept of ring signatures. A ring signature is a simplified group signature without any manager. It protects the anonymity of a signer. The first scheme proposed by Rivest et al. was based on RSA cryptosystem and certificate based public key setting. The first ring signature scheme based on DLP was proposed by Abe, Ohkubo, and Suzuki. Their scheme is also based on the general certificate-based public key setting too. In 2002, Zhang and Kim proposed a new ID-based ring signature scheme using pairings. Later Lin and Wu proposed a more efficient ID-based ring signature scheme. Both these schemes have some inconsistency in computational aspect. In this paper we propose a new ID-based ring signature scheme and a proxy ring signature scheme. Both the schemes are more efficient than existing one. These schemes also take care of the inconsistencies in above two schemes.Comment: Published with ePrint Archiv

Utilization of Virtual Reality for General Education Purposes

The use of Virtual Reality (VR) in a variety of professional, military, governmental, and educational fields has continued to expand over the past several decades, and the recent Covid-19 pandemic has brought attention to this field. This study surveys 154 college students over 23 questions that include various demographics that can be used to look for discriminators, multiple-choice VR-related questions, as well as a few free-form questions about use of VR in learning environments. The students’ experience with, interest in, and thoughts on how to best use VR vary considerably. The Covid-19 pandemic is found to have limited impact thus far in terms of VR use, but the interest in using VR in schools since then has generally increased quite a bit. Commitment to invest in VR were it to be expanded and provide continual feedback varies quite a bit as well but is strong. A statistical 2 analysis shows that, at a high confidence level, males generally are more experienced with VR in general, have a greater interest in seeing VR implemented further, and are more committed to radical changes in educational methodology than females are. In addition, it is found that Hispanics/Latinos, Black / African Americans, Pacific Islanders, and those of mixed race are more inclined to provide continual feedback as regards the implementation of VR in the school curriculum than (non-Hispanic) White and Asian people are

Landscape Mapping and Tree Diversity Assessment of Pangi Valley: A Remote Tribal Area of Himachal Pradesh in Western Himalaya, India

Pangi valley in Chamba district of Himachal Pradesh is one of the remote tribal areas in Indian western Himalaya. The plant resources in its landscapes are flourishing under least anthropogenic conditions. For social upliftment of the tribals in this area, a number of developmental activities are being implemented by the government. A study was conducted for mapping of its landuse/landcover using satellite remote sensing to identify major forested landscapes in the region. It was followed by a detailed random stratified sampling of the forested landscapes for phytosociological estimation of its tree species. The 21.97 % of study area was estimated under forests followed by Scrublands and Grassy meadows (18.24 %). Majority of area (54.05 %) was Snow and Scree slopes. Among the forests, maximum area was occupied by Mixed Broad Leaved Forest LSE type (36.08%) followed by Cedrus deodara (26.94%) and Betula utilis (18.07%) forest LSE types. These species, owing to immense medicinal properties and value for their economic utilization, feature in threatened and endangered category list of plants. It is, therefore, recommended that the developmental activities may be implemented in scientific way, which may not pose threat to bioresources in this region

Efficiency of nalbuphine as an adjuvant to bupivancaine in lower limb orthopaedic surgery-a prospective study

Background: Spinal Anaesthesia is a well-known technique of performing lower limb orthopaedic surgeries. It has a shorter duration of action and early arising postoperative pain due to which various adjuvant needs to be added and their roles are being evaluated in various studies. Intrathecal opioids act synergistically with local anaesthetics and thus intensifying the sensory block without having any effect on sympathetic blockage. The main aim of present study is to investigate and evaluate the effectiveness of intrathecal nalbuphine (preservative free) as an adjuvant and also the efficacy of nalbuphine for postoperative analgesia and its complications if there are any.Methods: A total of 60 patients were included in this study belonging to ASA I and ASA II score with normal coagulation profile. Patients were randomly divided into 2 groups of 30 patients each. Group I receiving 3 ml of hyperbaric bupivacaine 0.5%+1.0mgm of nalbuphine (preservative free) injection made in 0.5 ml normal saline intrathecally. Group II received 3 ml of hyperbaric bupivacaine 0.5%+0.5 ml injection Normal saline intrathecally. The following criteria were noted. The onset of sensory blockade and complete motor blockade highest level of sensory blockade, duration of sensory blockade, duration of motor and duration of effective analgesia were recorded. Any hemodynamic alterations were also noted.Results: The mean time for the onset of sensory blockage was 56 sec in Group I and 59 sec in Group II (control). The difference were statistically insignificant (p>0.05). The mean onset of motor blockage was 106 sec in Group I and 208 sec in Group II (control). The difference was statically insignificant. The peak onset time in Group I and Group II was 372 sec and 220 sec respectively (p>0.05). Two segment regression times for sensory blockage was prolonged in Group I (118.20±8.56 min) compared to Group II (104.56±15.20 mins).Conclusions: The duration of postoperative analgesia was 6-8 hours in Group I compared to 3-4 hours in Group II (p value= 0.0001, statistically significant)

Spectral properties of doped bilayer cuprates at finite temperatures

Recently, angle-resolved photoemission spectroscopy measurements on Bi2Sr2CaCu2O8+δ, which possesses two CuO2 layers in the same unit cell, have yielded very interesting results. For the overdoped samples, these results show a splitting of electronic states near k=(π, 0) point of Brillioun zone. On the other hand, no splitting is observed in the underdoped samples. In view of this, the detailed studies including the doping and temperature dependence of the spectral properties become desirable. In this paper, we consider cuprates possessing two CuO2 layers per unit cell. Each layer in the system is described by the t-t'-J model and the two layers are coupled via an intrabilayer hopping term (t ⊥) and an intrabilayer exchange coupling (J ⊥). A self-consistent perturbation approach is used to calculate the electronic spectral function for different values of hole density, hole momentum and temperature. We find that the imaginary part of the self energy is strongly momentum dependent which contradicts the suggestion that the Fermi surface of cuprates may be described by marginal Fermi liquid theory. We have calculated the spectral function for various values of intrabilayer parameters t ⊥ and J ⊥. For larger values of intrabilayer interactions we observe the splitting in the quasi-particle peak at k=(π, 0) which is in agreement with the recent observations. The splitting is also found to be sensitive to the hole concentration as well as the temperature of the system. We have also discussed the reasons why the splitting is absent in underdoped bilayer cuprates at low temperature

Method to Enhance the Operation of an Optical Inspection Instrument Using Spatial Light Modulators

For many aspheric and freeform optical components, existing interferometric solutions require a custom computer-generated hologram (CGH) to characterize the part. The overall objective of this research is to develop hardware and a procedure to produce a combined, dynamic, Hartmann/ Digital Holographic interferometry inspection system for a wide range of advanced optical components, including aspheric and freeform optics. This new instrument would have greater versatility and dynamic range than currently available measurement systems. The method uses a spatial light modulator to pre-condition wavefronts for imaging, interferometry, and data processing to improve the resolution and versatility of an optical inspection instrument. Existing interferometers and Hartmann inspection systems have either too small a dynamic range or insufficient resolution to characterize conveniently unusual optical surfaces like aspherical and freeform optics. For interferometers, a specially produced, computer-generated holographic optical element is needed to transform the wavefront to within the range of the interferometer. A new hybrid wavefront sensor employs newly available spatial light modulators (SLMs) as programmable holographic optical elements (HOEs). The HOE is programmed to enable the same instrument to inspect an optical element in stages, first by a Hartmann measurement, which has a very large dynamic range but less resolution. The first measurement provides the information required to precondition a reference wave that avails the measurement process to the more precise phase shifting interferometry. The SLM preconditions a wavefront before it is used to inspect an optical component. This adds important features to an optical inspection system, enabling not just wavefront conditioning for null testing and dynamic range extension, but also the creation of hybrid measurement procedures. This, for example, allows the combination of dynamic digital holography and Hartmann sensing procedures to cover a virtually unlimited dynamic range with high resolution. Digital holography technology brings all of the power and benefits of digital holographic interferometry to the requirement, while Hartmann-type wavefront sensors bring deflectometry technologies to the solution. The SLM can be used to generate arbitrary wavefronts in one leg of the interferometer, thereby greatly simplifying its use and extending its range. The SLM can also be used to modify the system into a dynamic Shack-Hartmann system, which is useful for optical components with large amounts of slope. By integrating these capabilities into a single instrument, the system will have tremendous flexibility to measure a variety of optical shapes accurately