Physical-Layer Security: Combining Error Control Coding and Cryptography

In this paper we consider tandem error control coding and cryptography in the setting of the {\em wiretap channel} due to Wyner. In a typical communications system a cryptographic application is run at a layer above the physical layer and assumes the channel is error free. However, in any real application the channels for friendly users and passive eavesdroppers are not error free and Wyner's wiretap model addresses this scenario. Using this model, we show the security of a common cryptographic primitive, i.e. a keystream generator based on linear feedback shift registers (LFSR), can be strengthened by exploiting properties of the physical layer. A passive eavesdropper can be made to experience greater difficulty in cracking an LFSR-based cryptographic system insomuch that the computational complexity of discovering the secret key increases by orders of magnitude, or is altogether infeasible. This result is shown for two fast correlation attacks originally presented by Meier and Staffelbach, in the context of channel errors due to the wiretap channel model.Comment: 12 pages, 5 figures. Submitted and accepted to the International Conference on Communications (ICC) 2009. v2: equivalent to the version that will be published in the conference proceedings. Has some altered notation from version 1 as well as slight changes in the wording to make the paper more readable and easier to understan

D=2 N=(2,2) Semi Chiral Vector Multiplet

We describe a new 1+1 dimensional N=(2,2) vector multiplet that naturally couples to semi chiral superfields in the sense that the gauged supercovariant derivative algebra is only consistent with imposing covariantly semi chiral superfield constraints. It has the advantages that its prepotentials shift by semi chiral superfields under gauge transformations. We also see that the multiplet relates the chiral vector multiplet with the twisted chiral vector multiplet by reducing to either multiplet under appropriate limits without being reducible in terms of the chiral and twisted chiral vector multiplet. This is explained from the superspace geometrical point of view as the result of possessing a symmetry under the discrete supercoordinate transformation that is responsible for mirror copies of supermultiplets. We then describe how to gauge a non linear sigma model with semi chiral superfields using the prepotentials of the new multiplet.Comment: 15 page

Extremely Sub-wavelength Planar Magnetic Metamaterials

We present highly sub-wavelength magnetic metamaterials designed for operation at radio frequencies (RFs). A dual layer design consisting of independent planar spiral elements enables experimental demonstration of a unit cell size (a) that is ~ 700 times smaller than the resonant wavelength ({\lambda}0). Simulations indicate that utilization of a conductive via to connect spiral layers permits further optimization and we achieve a unit cell that is {\lambda}0/a ~ 2000. Magnetic metamaterials are characterized by a novel time domain method which permits determination of the complex magnetic response. Numerical simulations are performed to support experimental data and we find excellent agreement. These new designs make metamaterial low frequency experimental investigations practical and suggest their use for study of magneto-inductive waves, levitation, and further enable potential RF applications.Comment: 5 pages, 4 figure

Holographic interference lithography for integrated optics

In this paper, some of our recent work in the use of holographic interference lithography and various material removal techniques to corrugate thin-film optical waveguides are reviewed. The specific applications of these periodic thin-film devices in the distributed feedback and distributed Bragg reflector semiconductor laser, and as output grating couplers, are described. Recent results in the use and fabrication of chirped and curved-line gratings are also summarized

DYNAMIC ELUTRIATION MEASUREMENT IN A CONTINUOUSLY OPERATED BUBBLING FLUIDIZED BED

Measurements were performed using a novel thermal mass flow meter. The dynamic behaviour of the total elutriation rate was monitored from start-up until a steady rate was achieved. It was found that the elutriation rate at unsteady conditions can be as much as 5 times that of the steady value and that it can take more than an hour to reach steady state. This is attributed to the dynamic changes of the fines distribution between the fluidized bed and dipleg. It was further shown that a steady dipleg height does not indicate steady elutriation rates. Using the flow meter to confirm steady state measurements, elutriation constants were determined for the glass bead - air system at different superficial velocities

Influence of Simulated Harvest on Iowa Wild Turkey Populations

Computer models were used to simulate autumn harvest of a wild turkey (Meleagris gallopava silvestrus) population in Iowa. Parameters were based on estimates of survival rates, fecundity rates, and age and sex ratios from field studies in mixed forest-farmland from 1977 to 1981. Simulations with average survival and fecundity parameters resulted in a population growth rate of 4% per year. If female survival rates were reduced 4.8% or fecundity was reduced 13.9%, the population became stationary. Interaction of hunting and non-hunting mortality was incorporated according to 3 hypotheses: additive, completely compensatory, and compensatory mortality rates up to a threshold. Estimated allowable autumn harvest rates, based on the goal of a stationary breeding population, ranged from 4.7% to 9.5 % of the females and from 14.8% to 28.4% of the males. At these harvest levels, female survival would have to increase approximately 5% and fecundity 16% to compensate for the harvest and return the population to former growth rates. The time required for the total population to decline by 25% of present levels ranged from more than 100 years at 5% harvest rate under additive mortality to almost 74 years at 10% harvest rate under the threshold theory

Natural functionally-graded composites in hard-to-soft tissue (bone- tendon) junctions

Composite materials are often functionally engineered to imbue desired mechanical properties in materials for structural applications. Nature has long engaged in such composite engineering of biological organisms, which has evolved in both flora and fauna in response to specific mechanical demands. Incorporation of phenolic compounds (like lignin) in stiffening cell assemblies in plant basts, or of silica in plant leaves to resist chomping insect incursions, are good examples in the plant world. Skeletal bone in vertebrates is the classic example in the animal kingdom, a composite of flexible fibrous polymerized organic protein and platy-crystalline inorganic mineral that results in a mechanically strong, hard, tough tissue. The musculo-skeletal system of vertebrates in fact comprises a variety of both hard and soft tissue types (bone, cartilage, tendon, ligament), generative cell types (osteoblasts, chondrocytes, tenocytes, fibroblasts, all of which can derive from multipotent mesenchymal stem cell precursors), and fibrous connective-tissue proteins (chiefly collagen, types I and II) that are susceptible to varying degrees of mineralization. In the case of bone, mineralization is extensive and forms a bi-continuous composite of mineral (chiefly partially-carbonated hydroxyapatite [Ca10(PO4,CO3)6(OH)2] and precursors) and collagen (a triple a-helix polypeptide) that self-assembles into protein fibrils (mostly type I collagen). Bone continually remodels itself and also re-forms as a consequence of injury or around implanted prostheses (such as knee and hip prostheses). High-resolution analytical TEM reveals [1] a mineralization mechanism which entails initial creation, at the mitochondria of bone-forming cells (osteoblasts), of pre-packaged vesicles that fill with a calcium-phosphate hydrogel and thereafter migrate through the cell wall. The vesicle contents subsequently crystallize [2] in the extra-cellular space with the dissolution of the vesicle containment wall, shortly before self-assembling collagen is expressed from the osteoblasts, providing a “just-in-time” ready source of Ca and P for mineralization of collagen fibrils with close to (though not identical with) the Ca/P ratio of hydroxyapatite found in the mature bone composite. The critical connective junctions between different tissue types in the musculo-skeletal system (bone, cartilage, tendon, muscle, ligament) involve several hard-tissue/soft-tissue interfaces, characterized by gradients in mineralization, cell type, cell morphology, and collagen self-assembly modes. For example, standard procedure for re-attachment of ruptured tendons—by surgically re-locating the tendon proximally to bone—re-establishes the important bone-tendon junction (enthesis) in a period of about one year. The process proceeds through growth, contiguous to the (fully mineralized) bone surface, of a partially-mineralized fibrocartilage layer (comprising collagen, expressed by chondrocyte cells, that self-assembles into principally Type II and Type X collagens). TEM [3] of ovine models shows that mineralization of this cartilaginous layer appears to occur via the identical mechanism established [1,2] for bone mineralization but initiated instead by chondrocyte cells. SEM [3] reveals that the cell-type in the remaining unmineralized cartilage portion gradually morphs into tenocytes, which form more elastic tendon fibers comprising, again, mostly Type I collagen (but also Types III, IV, V and IX self-assembly motifs). The resulting hard-tissue/soft-tissue enthesis junction is thus seen [3] to be a multiply graded interface involving three different cell types, several different collagen self-assembly motifs, and the functional gradation of a composite material paradigm spanning fully-hard tissue (bone) to fully-soft tissue (tendon). [1] S. Boonrungsiman, E. Gentleman, R. Carzaniga, N.D. Evans, D.W. McComb, A. E. Porter and M.M. Stevens, PNAS 109 (2012) 141. [2] V. Benezra, L. W. Hobbs and M. Spector, Biomaterials 23 (2001) 725; A. E. Porter, L. W. Hobbs, V. Benezra and M. Spector, Biomaterials 23 (2001) 921. [3] L. W. Hobbs, H. Wang, W. M. Reese, B. M. Tomerline, T. Y. C. Lim, A. E. Porter, M. Walton and M. J. Cotton, Microscopy & Microanalysis 19 (2013) 182

Pertumbuhan Kacang Hias (Arachis Pintoi) Pada Media Tanah Pasca Penambangan Batubara Yang Diperkaya Mikoriza, Kapur Dan Pupuk Npk

This study aimed to determine the effects of the provision of arbuscular mycorrhizal fungi (AMF), the provision of lime, and the provision of NPK fertilizer, and the interaction effect of the provision of Arbuscular mycorrhizal fungi (AMF), lime and NPK fertilizers in promoting the growth of pinto peanut in the soil media of post-mining land. The research method used was a completely randomized design (CRD) three-factor factorial with the first factor is the type of inoculant FMA (M) = 3 levels, the second factor is the provision of lime (K) = 3 levels, and the third factor is the NPK fertilizer (P) = 3 levels. These results indicated that the interaction between AMF Glomus sp. and NPK fertilizer dose of 1 gram/polybag can increase height increase pinto peanut plants for 34.16 % of the controls. The interaction between AMF Gigaspora sp. The lime dose of 50 % Al-dd and Fertilizers NPK dose of 1 gram/polybag can increase the growth of leaves pinto peanut plants at 108.33 % of the controls. The interaction between AMF Glomus sp. and NPK fertilizer dose of 2 grams/polybag can increase canopy and root biomass pinto peanut plants at 245.21 % of the controls. The interaction between AMF Glomus sp. and NPK fertilizer dose of 2 grams/polybag can increase canopy and root biomass pinto peanut plants at 245.21 % of the controls. Level relative mycorrhizal dependency (RMD) was influenced by the type of AMF plant inoculated host. Highest RMD shown in pinto peanut using AMF Glomus sp. is 31.99% at moderately dependent