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This study proposes a photonic crystal fiber (PCF) made of fused silica glass with the core infiltrated with 1,2-dibromoethane ( C 2 H 4 B r 2 ) as a new source of supercontinuum light pulses. Due to the modifications of the PCF's structure geometry, a number of computer simulations investigating their optimized structures has been carried out. This aimed at achieving flat near-zero dispersion and zero dispersion wavelength matching of the pump wavelength for efficient spectral broadening. Based on the obtained results, the structural geometries of two C 2 H 4 B r 2 -core PCFs were optimized using numerical modeling for broadband supercontinuum (SC) generation. The first fiber structure with a lattice constant 1.5 µm and filling factor 0.4 has all-normal dispersion profile. The SC with a broadened spectral bandwidth from 0.64 to 1.70 µm is generated by pump pulses centered at a wavelength of 1.03 µm, 120 fs duration, and energy of 1.5 nJ. The second proposed structure-with lattice constant 1.5 µm and filling factor 0.65-has anomalous dispersion for wavelengths longer than 1.03 µm. We obtained high coherence of the SC pulses in the anomalous dispersion range over wavelengths of 0.7-2.4 µm with the same pump pulse as the first fiber and with input energy of 0.09 nJ. These fibers would be interesting candidates for all-fiber SC sources operating with low-energy pump lasers as cost-effective alternatives to glass core fibers.

A photonic crystal fiber (PCF) made of fused silica glass, infiltrated with carbon tetrachloride (CCl 4 ), is proposed as a new source of supercontinuum (SC) light. Guiding properties in terms of effective refractive index, attenuation, and dispersion of the fundamental mode are studied numerically. As a result, two optimized structures are selected and verified against SC generation in detail. The dispersion characteristic of the first structure has the zero-dispersion wavelength at 1.252 μm, while the dispersion characteristic of the second structure is all-normal and equals -4.37  ps·nm -1 ·km -1 at 1.55 μm. SC generation was demonstrated for the wavelengths 1.064 μm, 1.35 μm, and 1.55 μm. We prove the possibility of coherent, octave-spanning SC generation with 300 fs pulses with only 0.8 nJ of energy in-coupled into the core with each of the studied structures. Proposed fibers are fully compatible with all-silica fiber systems and PCFs with wide mode area, and can also be used for all-fiber SC sources. The proposed solution may lead to new low-cost all-fiber optical systems.

In this paper we present a study on the dispersion characteristics in the suspended-core optical fibers made of borosilicate of NC21A glass infiltrated with water. Replacement of air with water results in dramatic improvement of the dispersion characteristics in the fibers, valuable in the process of supercontinuum generation. A near-zero flat dispersion can be achieved in the anomalous or normal dispersion range for various diameters of the core.

Tracing movements could assist the implementation of bio-containment measures during a disease outbreak. To evaluate the potential for implementing a tracing system for a poultry supply chain in northern Vietnam, a four-month longitudinal study was conducted to identify marketing practices associated with poultry traceability. Poultry sold in batches were traced between farms and markets, and their traceability was assessed upon market arrival. A total of 315 batches were released from the farms; 37% arrived at a market, from which 57.3% were 'traceable'. The results of the multivariable analysis showed that traceability was associated with farms operating through no more than two traders (Odds ratio [OR] = 5.97, 95% CI 1.15-30.92) and batches brought to the market on the day of purchase (OR = 4.05, 95% CI 1.23-13.27). No specific incentives were provided to farmers or traders. Results suggest that there is potential for implementing a poultry traceability scheme, although the tracing methodology should be refined.

Background: The structure of contact between individuals plays an important role in the incursion and spread of contagious diseases in both human and animal populations. In the case of avian influenza, the movement of live birds is a well known risk factor for the geographic dissemination of the virus among poultry flocks. Live bird markets (LBM's) contribute to the epidemiology of avian influenza due to their demographic characteristics and the presence of HPAI H5N1 virus lineages. The relationship between poultry producers and live poultry traders (LPT's) that operate in LBM's has not been adequately documented in HPAI H5N1-affected SE Asian countries. The aims of this study were to document and study the flow of live poultry in a poultry trade network in northern Vietnam, and explore its potential role in the risk for HPAI H5N1 during 2003 to 2006., Results: Our results indicate that LPT's trading for less than a year and operating at retail markets are more likely to source poultry from flocks located in communes with a past history of HPAI H5N1 outbreaks during 2003 to 2006 than LPT's trading longer than a year and operating at wholesale markets. The results of the network analysis indicate that LPT's tend to link communes of similar infection status., Conclusions: Our study provides evidence which can be used for informing policies aimed at encouraging more biosecure practices of LPT's operating at authorised LBM's. The results suggest that LPT's play a role in HPAI H5N1 transmission and may contribute to perpetuating HPAI H5N1 virus circulation amongst certain groups of communes. The impact of current disease prevention and control interventions could be enhanced by disseminating information about outbreak risk and the implementation of a formal data recording scheme at LBM's for all incoming and outgoing LPT's.