Degenerate four-wave mixing in triply-resonant Kerr cavities

We demonstrate theoretical conditions for highly-efficient degenerate four-wave mixing in triply-resonant nonlinear (Kerr) cavities. We employ a general and accurate temporal coupled-mode analysis in which the interaction of light in arbitrary microcavities is expressed in terms a set of coupling coefficients that we rigorously derive from the full Maxwell equations. Using the coupled-mode theory, we show that light consisting of an input signal of frequency $\omega_0-\Delta \omega$ can, in the presence of pump light at $\omega_0$, be converted with quantum-limited efficiency into an output shifted signal of frequency $\omega_0 + \Delta \omega$, and we derive expressions for the critical input powers at which this occurs. We find that critical powers in the order of 10mW assuming very conservative cavity parameters (modal volumes $\sim10$ cubic wavelengths and quality factors $\sim1000$. The standard Manley-Rowe efficiency limits are obtained from the solution of the classical coupled-mode equations, although we also derive them from simple photon-counting "quantum" arguments. Finally, using a linear stability analysis, we demonstrate that maximal conversion efficiency can be retained even in the presence of self- and cross-phase modulation effects that generally act to disrupt the resonance condition.Comment: 13 pages, 8 figures. To appear in Physical Review

Delay-bandwidth and delay-loss limitations for cloaking of large objects

Based on a simple model of ground-plane cloaking, we argue that the diffculty of cloaking is fundamentally limited by delay-loss and delaylbandwidth/size limitations that worsen as the size of the object to be cloaked increases relative to the wavelength. These considerations must be taken into account when scaling experimental cloaking demonstrations from wavelength-scale objects towards larger sizes, and suggest quantitative material/loss challenges in cloaking human-scale objects.Comment: 4 pages, 2 figure

KOMBINASI DAUN GAMAL (Gliricidia sepium) DAN DAUN PAPAYA (Carica papaya) DALAM RANSUM TERNAK KAMBING KACANG (Combination of gamal (Gliricidia sepium) and papaya (Carica papaya) leaves in ration supplement of kacang goat)

This study examined the effect of the use of gliricidia leaves and papaya leaves in rations on the growth of kacang goats. The male Kacang goat, growth age (1 - 1.5 years) as many as 12 tails with an initial body weight of 13.55 ± 0.036 kg (BW ± standard error) were used as experimental animals. The experimental design used is a complete randomized design of factorial patterns 2 x 2 with two factors, namely, gliricidia leaf factor (A) with two levels of giving (a1 15% and a2 30%), papaya leaf factor (B) with two levels of giving (b1 5% and b2 10%) so that 4 treatment combinations are formed. The combination of treatments is, a1b1, a1b2, a2b1 and a2b2. The treatment was repeated 3 times to form 12 experimental units. The parameters tested were the consumption and digesting of dry matter as well as ration nutrients, weight gain and efficiency of ration use. The data was analyzed using analysis of variance (ANOVA) and followed by the Duncan test to compare between treatments. The results showed that there was no significant interaction (P >0.05) on all the parameters measured. The response of goat to parameters is more influenced by the single effect of gliricidia leaves and papaya leaves. The response to the use of gliricidia leaves is 30% and papaya leaves are 10% higher than the level of use below. It was concluded that the use of gliricidia leaves and papaya leaves can increase goat growth but the combination has not provided a significant interaction for it requires further study with a combination of higher levels

Determination of Photon Shielding Parameters for Soils in Mangrove Forests

The mass attenuation coefficient (MAC), effective atomic number (Zeff), and effective electron density (Neff) values of soils in mangrove forests across the Philippine islands were investigated. In addition, ENDF/B-VI.8 cross-section data library was used for interpolating Zeff and Neff values. Photon energies considered in this study ranged from 59.5–1332 keV. MAC values were obtained using MCNP5 and PHITS Monte Carlo (MC) simulations and were found to be in good agreement with XCOM and values in literature. Results for Zeff were in good agreement with values obtained using Phy-X/ZeXTRa program. Each shielding parameter was investigated as a function of SiO2 concentrations

SONAR: Automatic detection of cyber security events over the twitter stream

© 2017 ACM. Everyday, security- experts face a grim ing number of security events that affecting people well-being, their information systems and sometimes the critical infrastructure. The sooner they can detect and understand these threats, the more they can mitigate and forensically investigate them Therefore, they need to have a situation awareness of the existing security events and their possible effects. However, given the large number of events, it can be difficult for security analysts and researchers to handle this flow of information in an adequate manner and answer the following questions in near- real time: what are the current security events? How long do they last? In this paper, we will try to answer these issues by leveraging social networks that contain a massive amount of valuable information on many topics. I lowever. because of the very- high volume, extracting meaningful information can be challenging. For this reason, we propose SONAR: An automatic, self-learned framework that can detect geolocate and categorize cyber security events in near-real time over the Twitter stream. SONAR is based on a taxonomy- of cyber security events and a set of seed keywords describing type of events that we want to follow in order to start detecting events. Using these seed keywords, it automatically discovers new relevant keywords such as malware names to enhance the range of detection while staying in the same domain. Using a custom taxonomy describing all type of cyber threats, we demonstrate the capabilities of SONAR on a dataset of approximately 47.8 million tweets related to cyber security in the last 9 months. SONAR could efficiently and effectively detect, categorize and monitor cyber security related events before getting on the security news, and it could automatically discover new security terminologies with their event. Additionally. SONAR is highly scalable and customizable by design; therefore we could adapt SONAR framework for virtually any type of events that experts are interested in

General scaling limitations of ground-plane and isolated-object cloaks

We prove that, for arbitrary three-dimensional transformation-based invisibility cloaking of an object above a ground plane or of isolated object, there are practical constraints that increase with the object size. In particular, we show that the cloak thickness must scale proportional to the thickness of the object being cloaked, assuming bounded refractive indices, and that absorption discrepancies and other imperfections must scale inversely with the object thickness. For isolated objects, we also show that bounded refractive indices imply a lower bound on the effective cross-section.Comment: 7 pages, 3 figure

Population structure and phylogeography of the Gentoo Penguin (Pygoscelis papua) across the Scotia Arc

Climate change, fisheries' pressure on penguin prey, and direct human disturbance of wildlife have all been implicated in causing large shifts in the abundance and distribution of penguins in the Southern Ocean. Without mark-recapture studies, understanding how colonies form and, by extension, how ranges shift is challenging. Genetic studies, particularly focused on newly established colonies, provide a snapshot of colonization and can reveal the extent to which shifts in abundance and occupancy result from changes in demographic rates (e.g., reproduction and survival) or migration among suitable patches of habitat. Here, we describe the population structure of a colonial seabird breeding across a large latitudinal range in the Southern Ocean. Using multilocus microsatellite genotype data from 510 Gentoo penguin (Pygoscelis papua) individuals from 14 colonies along the Scotia Arc and Antarctic Peninsula, together with mitochondrial DNA data, we find strong genetic differentiation between colonies north and south of the Polar Front, that coincides geographically with the taxonomic boundary separating the subspecies P. p. papua and P. p. ellsworthii. Using a discrete Bayesian phylogeographic approach, we show that southern Gentoos expanded from a possible glacial refuge in the center of their current range, colonizing regions to the north and south through rare, long-distance dispersal. Our findings show that this dispersal is important for new colony foundation and range expansion in a seabird species that ordinarily exhibits high levels of natal philopatry, though persistent oceanographic features serve as barriers to movement

Nonlinear harmonic generation and devices in doubly-resonant Kerr cavities

We describea theoretical analysis of the nonlinear dynamics of third-harmonic generation ($\omega\to3\omega$) via Kerr (\chithree) nonlinearities in a resonant cavity with resonances at both $\omega$ and $3\omega$. Such a doubly resonant cavity greatly reduces the required power for efficient harmonic generation, by a factor of $\sim V/Q^2$ where $V$ is the modal volume and $Q$ is the lifetime, and can even exhibit 100% harmonic conversion efficiency at a critical input power. However, we show that it also exhibits a rich variety of nonlinear dynamics, such as multistable solutions and long-period limit cycles.We describe how to compensate for self/cross-phase modulation (which otherwise shifts the cavity frequencies out of resonance), and how to excite the different stable solutions (and especially the high-efficiency solutions) by specially modulated input pulses.Comment: 12 pages, 12 figure

Semaphorin 3A Is Effective in Reducing Both Inflammation and Angiogenesis in a Mouse Model of Bronchial Asthma

Semaphorin 3A (sema3A) belongs to the sub-family of the immune semaphorins that function as regulators of immune-mediated inflammation. Sema3A is a membrane associated molecule on T regulatory cells and on B regulatory cells. Being transiently ligated to the cell surface of these cells it is suggested to be a useful marker for evaluating their functional status. In earlier studies, we found that reduced sema3A concentration in the serum of asthma patients as well as reduced expression by Treg cells correlates with asthma disease severity. Stimulation of Treg cells with recombinant sema3A induced a significant increase in FoxP3 and IL-10 expression. To find out if sema3A can be of benefit to asthma patients, we evaluated the effect of sema3A injection in a mouse model of asthma. BALB\c-mice were sensitized using ovalbumin (OVA) + adjuvant for 15 days followed by OVA aerosol inhalation over five consecutive days. Four hours following air ways sensitization on each of the above days- 15 of these mice were injected intraperitoneally with 50 μg per mouse of recombinant human sema3A-FR and the remaining 15 mice were injected with a similarly purified vehicle. Five days later the mice were sacrificed, broncheo-alveolar lavage (BAL) was collected and formalin-fixed lung biopsies taken and analyzed. In sema3A treated mice, only 20% of the bronchioles and arterioles were infiltrated by inflammatory cells as compared to 90% in the control group (p = 0.0079). In addition, eosinophil infiltration was also significantly increased in the control group as compared with the sema3A treated mice. In sema3A treated mice we noticed only a small number of mononuclear and neutrophil cells in the BAL while in the control mice, the BAL was enriched with mononuclear and neutrophil cells. Finally, in the control mice, angiogenesis was significantly increased in comparison with sema3A treated mice as evidenced by the reduced concentration of microvessels in the lungs of sema3A treated mice. To conclude, we find that in this asthma model, sema3A functions as a potent suppressor of asthma related inflammation that has the potential to be further developed as a new therapeutic for the treatment of asthma