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We explore the use of cylindrical metasurfaces in providing several illusion mechanisms including scattering cancellation and creating fictitious line sources. We present the general synthesis approach that leads to such phenomena by modeling the metasurface with effective polarizability tensors and by applying boundary conditions to connect the tangential components of the desired fields to the required surface polarization current densities that generate such fields. We then use these required surface polarizations to obtain the effective polarizabilities for the synthesis of the metasurface. We demonstrate the use of this general method for the synthesis of metasurfaces that lead to scattering cancellation and illusion effects and discuss practical scenarios by using loaded dipole antennas to realize the discretized polarization current densities. This study is the first fundamental step that may lead to interesting electromagnetic applications, like stealth technology, antenna synthesis, wireless power transfer, sensors, cylindrical absorbers, etc.

We present a general theory of exceptional points of degeneracy (EPD) in periodically time-variant systems. We show that even a single resonator with a time-periodic component is able to develop EPDs, contrary to parity-time- (PT) symmetric systems that require two coupled resonators. An EPD is a special point in a system parameter space at which two or more eigenmodes coalesce in both their eigenvalues and eigenvectors into a single degenerate eigenmode. We demonstrate the conditions for EPDs to exist when they are directly induced by time-periodic variation of a system without loss and gain elements. We also show that a single resonator system with zero time-average loss-gain exhibits EPDs with purely real resonance frequencies, yet the resonator energy grows algebraically in time since energy is injected into the system from the time-variation mechanism. Although the introduced concept and formalism are general for any time-periodic system, here, we focus on the occurrence of EPDs in a single LC resonator with time-periodic modulation. These findings have significant importance in various electromagnetic and photonic systems and pave the way for many applications, such as sensors, amplifiers, and modulators. We show a potential application of this time-varying EPD as a highly sensitive sensor.

Background&Objective: Hospital infection is one of the important determinants on lengthening hospitalization and increasing the costs and mortality rates in hospitals. Intensive Care Unit (ICU) is one of the wards that are most afflicted with the incidence of this morbidity. This study involves investigating the incidence of infection in one of the Intensive Care Units. Materials&Methods: This study was designed in the form of a prospective cohort which was implemented on patients who were hospitalized in the ICU of Khatamol Anbia Hospital from September 21st 2002 for at least 72 hours and didn’t reveal signs of infection. The status and duration of using tracheal tube, ventilator, urinary catheter, and venous catheter, the duration of hospitalization in ICU and the time infection appeared were all recorded. Results: During the six months spent on this study, 234 patients were hospitalized in ICU, among which 50 patients were investigated. The group of these 50 patients cumulatively spent 528 days in ICU. During their hospitalization, 9 cases of infection occurred in these patients. The incidence of infection was 18% (with a 95% confidence interval of 7.35% to 28.65%). The incidence rate was 17 patients in 1000 person-year of hospitalization in ICU (with a 95% confidence interval of 8.8 to 106.3). Conclusion: Hospital infection is a relatively common complication among patients who have been hospitalized in ICU for at least 3 days. The frequency of infection reported in Iran is equal or more than the results of studies carried out in other parts of the world.

Biological and reproduction characteristics of female big-eye kilka (Clupeonella grimmi) including body weight, fork length, age, gonad development stages, gonad weight, ganado somatic ratio (GSR) were studied. We sampled 808 fish specimens from the Southern Caspian Sea, Babolsar Area during December 2002 to May 2003. Gonad development stages were assessed through tissue sectioning. Results revealed spawning peak to occur in early January. We also measured body weight as 8.88:f:0.08grams, fork length as 1.03±0.26mm, age as 3.6±0.03 years, gonad development stage as 3.67±0.03, gonad weight as 0.5±0.01 grams and ganado somatic ratio (GSR) as 5.39±0.1 in the specimens. Totally, five age classes, dominated by the 4+ years were distinguished while no 1+ year's age class was observed. The abundance of gonad developmental stages 2-5 was 18.19%, 14.60%, 48.89% and 18.32% respectively. Macroscopic (visual) and microscopic (tissue section) observations of oocyte revealed the same results for gonad development.

This research was carried out to study the feeding behaviour of Blue Swimmer Crab (Portunus pelagicus) in Hormuzgan province waters from October 2001 to December 2002. Samplings were done in different methods by presence on research vessels, fishing vessels and dhows in addition to collect the samples from stake-nets. 490 stomach contents were observed under steriomicroscope in which among them the number of full, semi-full and empty stomachs were 136,197 and 157, respectively. The food contents were classified into 4 main groups namely; fish, mollusc, crustacean and plankton. The Index of C.V. was estimated 32.04 . This figure shows that blue swimmer crab can be assumed as a gluttonous species.

A novel type of waveguide phase shifter utilizing tunable electromagnetic crystal (EMXT) surfaces is incorporated in a 16-element two-dimensional (2-D) millimeter wave (38 GHz) phase-scanned lens. EMXT surfaces integrating semiconductor varactors are used as the sidewalls of a waveguide to provide a tunable impedance boundary for the waveguide. The EMXT waveguides are used as 360[degrees] analog phase shifters as well as radiating elements to realize electronic beam scanning with microseconds of response time. The four-by-four array achieved +/ - 30[degrees] of beam scanning in both the E and H planes. The electrical and mechanical design, top-level array calibration, and scan performance of the 16-element proof-of-concept 2-D space fed phased array lens are described. The waveguide phase shifter insertion loss performance and plans for further improving insertion loss are discussed. The average insertion loss is expected to be less than 2.0 dB at an operating frequency of 38 GHz for GaAs substrate-based EMXT surfaces with planar Schottky diode tuning elements. This new type of EMXT waveguide array may provide a low-cost and high performance alternative to a conventional phased array. Index Terms--Electromagnetic crystal, lens antenna, phase shifters, phased arrays, varactors.