Population dynamics and reproduction biology of slender mudskipper (Scartelaos tenuis) from Hormuzgan Province creeks, Persian Gulf

Slender Mudskipper (Scartelaos tenuis) is one of the dominant fishes in inter-tidal mud flats area. Reproduction and population parameters of 2047 Slender mudskipper were studied monthly from october 2008 to september 2009. The asymptotic length (L∞) and growth coefficient (K) were estimated as 19.43(cm) and 0.64(yr-1), respectively. The minimum and maximum T.L. was 1.1 and 19.5cm, respectively. The value of to was -8.28, and Tmax was 4.6 year. The growth equation of Von Bertalanffy was obtained at L(t) = 19.43(1- exp (-0.64(t(-0.28))) for this species. The rates of natural mortality (M) on Pauly's empirical equation, was estimated 1.51 (yr-1). Five cohorts were distinguished annualy on Bhattacharya's method with mean length of 7.89, 11.42, 13.86, 15.6 and 16.81cm. Maximum recruitment was in Seprember at 18.8 percent. Reproductive studies showed that peak of maturity season occurred in April. The female to male ratio was calculated as 1:1.47 and chi-square analysis showed that it was statistically significant deviated from 1:1. LM50 is attained at a total length of 13.3cm. The mean of absolute and relative fecundity were 6742 (±1939) and 707 (±210), respectively. The length-weight relationship was as W= 0.02735 L 2.1655, that was isometric growth. Result showed that slender mudskipper population was in congenial condition, nevertheless less not evaluated

PCBs and DDTs in surface mangrove sediments from the south of Iran (ID NO. 048)

Mangrove sediments were collected during wet and dry seasons from nine stations in Khamir, Laft and natural reservoir mangrove-dense areas of Hormozgan province in the south of Iran. Σ PCBs ranged from 5.33 to 15.5 ng/g dry weight and the dominant congener was no.153. Average Σ DDTs for Khamir and Laft mangroves were 16.58 ± 1.51 and 18.8 ± 9.98 ng/g dry weight. DDT was more abundant than DDE and DDD isomers, which indicated the input of DDT. The sediment quality guideline shows that the concentration of Σ PCBs were below the ER-M guideline, whereas levels of Σ DDTs were between ER-L and ER-M. The mangrove ecosystem in Hormozgan province is suffering from urban and industrial development

Low Bias Negative Differential Resistance in Graphene Nanoribbon Superlattices

We theoretically investigate negative differential resistance (NDR) for ballistic transport in semiconducting armchair graphene nanoribbon (aGNR) superlattices (5 to 20 barriers) at low bias voltages V_SD < 500 mV. We combine the graphene Dirac Hamiltonian with the Landauer-B\"uttiker formalism to calculate the current I_SD through the system. We find three distinct transport regimes in which NDR occurs: (i) a "classical" regime for wide layers, through which the transport across band gaps is strongly suppressed, leading to alternating regions of nearly unity and zero transmission probabilities as a function of V_SD due to crossing of band gaps from different layers; (ii) a quantum regime dominated by superlattice miniband conduction, with current suppression arising from the misalignment of miniband states with increasing V_SD; and (iii) a Wannier-Stark ladder regime with current peaks occurring at the crossings of Wannier-Stark rungs from distinct ladders. We observe NDR at voltage biases as low as 10 mV with a high current density, making the aGNR superlattices attractive for device applications.Comment: 6 pages, 4 figure

A compact circularly polarized microstrip transmit-receive antenna for LAN applications

A circularly polarized microstrip antenna integrated within a 90°/180° hybrid network for the construction of a compact transmit-receive antenna is presented. The hybrid network allows a signal to be transmitted with a left-hand polarization and to be received with a right-hand polarization, while providing at least 20 dB of isolation between the transmitting and receiving ports. Simulated and measured results are presented

Present and Future Trends in Filters and Multiplexers

In the last 10 or 15 years, exciting new developments have occurred in the field of filters and multiplexers. The two words that best explain this phenomenon are “topology” and “technology.” Thus, this paper will cover new connections, new materials, and new processes. This paper summarizes what is new, describes the new devices, and avoids simply surveying the entire field. It is not possible to cover everything, and regrettably, some new and possibly exciting areas are omitted (such as filters fabricated using liquid crystal polymers, active element inclusion, extreme power devices used in accelerators), and others, , because something has to be left for the next paper! The paper does cover bandstop filters, intrinsically switched film bulk acoustic resonator, and barium–strontium–titanate filters, brand new derivations of lossy filter synthesis and dual-band filter synthesis, multimode networks, new work on optimal multiplexer (multiport network) configurations, and substrate integrated waveguide filters. In each of these areas significant new work has been recently performed and is presented in a summary format suitable for those thinking that the area of filters and multiplexers has become mature (stagnant) with nothing interesting to learn. Nothing could be further from the truth