Wide multiwavelength Brillouin-Raman fiber laser assisted by an arc-shaped fiber attenuator

A wide bandwidth, single-spacing half-open-cavity multiwavelength Brillouin-Raman fiber laser (MWBRFL) is demonstrated. The laser cavity contains a fiber loop mirror (FLM) with an arc-shaped optical fiber attenuator that is used to control the mirror reflectivity, thereby suppressing gain competition from longitudinal cavity modes. A tuning range of 45 nm with 632 lines at Raman and 1525 nm Brillouin pump powers of 1.2 W and 12 dBm can be achieved using the 10 dB arc-shaped optical fiber attenuator in the cavity. This is in comparison to 433 Stokes lines obtained over a 31 nm tuning range for the half-open MWBRFL cavity without any feedback power optimization. The MWBRFL has low power fluctuations of less than 0.1 dB over a 1 h test period. The inclusion of the arc-shaped optical fiber attenuator in the MWBRFL provides substantial control over the reflectivity of the FLM as well as improving the laser's tuning range to generate a high number of Brillouin Stokes signals.

A triangulation for passive design strategies in public hospital

This study touches on passive design elements used at the preparatory design stage of public hospital in Malaysia. Passive design is an aspect of sustainable architecture that needs to be understood and adopted in an environmentally sensitive architectural design. The most common problem is that the designers do not have proper guidelines for passive design to help them in designing a public hospital. Currently there is no comprehensive guidelines on passive design or sustainable architecture that may help designers. This consequently affects the increase of energy usage in hospitals. The intent of this study is to furnish evidence that the initial process of systematic design and guidance is essential in planning for a sustainable public hospital environment. In this study, the researcher uses a mixed method to obtain outcome for guideline. Through this method, a combination of qualitative and quantitative metadata to foster effective interventions to improve the quality of environmental friendly hospital design. The conclusions obtained from this study are to assist in the process of more efficient public hospital design. In addition to making these passive design guidelines as helpful in providing explanations and working to ensure that the guideline produced has credibility and meet the criteria.

Mechanically exfoliated In2Se3 as a saturable absorber for mode-locking a thulium-doped fluoride fiber laser operating in S-band

The rise of 2D materials since the discovery of graphene has been exponential. Their mechanical, electrical and optical properties are exceptional, similar to their 3D counterparts. In this paper, an α-In₂Se₃ crystal is mechanically exfoliated and transferred directly onto a fiber ferrule to serve as a saturable absorber (SA). A thulium-doped fluoride fiber is used as a gain medium to generate mode-locked pulses together with the In₂Se₃-based SA. The SA has a modulation depth of 14.6% and a saturation intensity of 0.4  kW/cm². The passively generated mode-locked pulses have a repetition rate of 6.93 MHz and a pulse width of 5.79 ps. The mode-locked pulses also have a signal-to-noise ratio of 65.4 dB and a time-bandwidth product of 0.36. The pulse energy and peak power are 0.179 nJ and 27.2 W, respectively.

Effects of dietary supplementation with enzymatically treated Artemisia annua on growth performance, intestinal morphology, digestive enzyme activities, immunity, and antioxidant capacity of heat-stressed broilers

The gastrointestinal tract is considered as one of the main target organs affected by heat stress. Phytogenic feed additives containing phenolics and flavonoids can improve the resistance of broilers to heat stress. This study was conducted to investigate the effects of dietary supplementation with enzymatically treated Artemisia annua (EA) on growth performance, intestinal morphology, digestive enzyme activities, immunity and antioxidant capacity of broilers challenged with heat stress. One hundred and forty-four 21-day-old male Arbor Acres broilers were randomly distributed into 3 treatments: 1) non-challenged control (CON); 2) heat-stress-challenged control (HS); and 3) heat-stress-challenged group + 1 g EA/kg diet (HS-EA). From 22 to 41 d, broilers in the CON group were housed at 22 ± 1°C, the HS and HS-EA groups, in which broilers were raised at 34 ± 1°C for 8 h (0900-1700 h) and the temperature for the rest time was the same as that of the CON group. The EA supplementation alleviated the compromised body weight gain and intestinal morphology impairment caused by heat stress challenge (P < 0.05). The EA attenuated heat-stress-induced decreased intestinal lipase, trypsin and total superoxide dismutase activities, and reduced intestinal secretory immunoglobulin A (SIgA) and IgG concentrations (P < 0.05). The EA inclusion prevented the elevation of intestinal malondialdehyde content and reduction of intestinal glutathione concentration induced by heat stress challenge (P < 0.05). The intestinal mRNA abundances of nuclear factor erythroid 2-related factor 2, heme oxygenase 1, glutathione peroxidase, gamma-glutamyl cysteine ligase larger catalytic subunit and gamma-glutamyl cysteine ligase smaller modulator subunit in heat-stressed broilers were increased in response to dietary EA treatment (P < 0.05). In conclusion, dietary supplementation of 1 g/kg EA could alleviate heat-stress-induced compromised growth performance and intestinal damage of broilers.

Investigation of Potential Grounding Compound for Portable Applications

<span>This paper applies to the electrical engineering world by making earthing system portable in providing low and acceptable resistance path. The system is develop in a small scale portable earthing system against the massiveness of Earth and becomes leverage if soil at the place is not suitable for plant grounding system. Hence, this paper presents findings on the research of new grounding medium material that will be housed in a small scale enclosure which behaves like native earth related earthing system by using kaolin and bauxite. The data obtained from lightning flashover testing, morphological and chemical composition of material analysis indicated that bauxite is more useful for portable grounding system application much better than kaolin in term of zero reference point function. The portable earthing system can be apply to air aviation systems , railway systems and military sectors particularly for electronic equipment zero referencing.</span>

All-fiber multimode interferometer for the generation of a switchable multi-wavelength thulium-doped fiber laser

A compact all-fiber multimode interferometer (MMI) designed to produce a switchable multi-wavelength thulium-doped fiber laser (TDFL) is proposed and demonstrated. The TDFL fiber ring cavity employs a 60-cm-long multimode fiber into the cavity to induce multimode interference and provide intensity-dependent loss in order to generate a multi-wavelength output. The suppression of mode competition and the overall stability of the TDFL are further improved by exploiting the filtering capability of a Sagnac loop. By increasing the pump power, a switchable wavelength output is allowed with a wavelength spacing of ∼1.8  nm. At 361 mW input pump power, nine laser lines are generated, with a maximum signal-to-noise ratio value of ∼36  dB and an output power of 3.3 mW. The multi-wavelength TDFL also exhibits great stability in one-hour operation with a wavelength drift of 0.2 nm. The proposed multi-wavelength TDFL has potential to be employed in future thulium-doped fiber amplifier-based telecommunication infrastructure and also may be applicable in areas such as sensing and spectroscopy, largely associated with its 2 μm wavelength output.

The impact of anticancer activity upon Beta vulgaris extract mediated biosynthesized silver nanoparticles (ag-NPs) against human breast (MCF-7), lung (A549) and pharynx (Hep-2) cancer cell lines

The present study tried for a phyto-synthetic method of producing silver nanoparticles (Ag-NPs) with size controlled as and eco-friendly route that can lead to their advanced production with decorative tranquil morphology. By inducing temperature fluctuation of the reaction mixture from 25 to 80°C the plasmon resonance band raised slowly which had an ultimate effect on size and shape of Ag-NPs as shown by UV-visible spectroscopy and TEM results. The biosynthesized nanoparticles showed good cytotoxic impact against MCF-7, A549 and Hep2 cells compared to normal cell lines. Compared to control plates, the percentage of cell growth inhibition was found to be high with as concentrations of Ag-NPs becomes more as determined by MTT assay. The AO/EtBr staining observations demonstrated that the mechanism of cell death induced by Ag-NPs was due to apoptosis in cancer cells. These present results propose that the silver nanoparticles (Ag-NPs) may be utilized as anticancer agents for the treatment of various cancer types. However, there is a need for study of in vivo examination of these nanoparticles to find their role and mechanism inside human body. Further, studies we plan to do biomarker fabrication from the green synthesized plant extract nanoparticles like silver, gold and copper nanoparticles with optimized shape and sizes and their enhancement of these noble nanoparticles.

Tunable passively Q-switched thulium-fluoride fiber laser in the S+/S band (1450.0 to 1512.0 nm) region using a single-walled carbon-nanotube-based saturable absorber

A tunable passively Q-switched for S+/S band thulium-fluoride fiber (TFF) laser using single-walled carbon nanotubes as a saturable absorber is proposed and demonstrated. The tunability of the proposed laser covers a wavelength region of 1450.0-1512.0 nm, with a range of 62.0 nm. Stable Q-switched operation can be obtained at a pump power of 115.7-229.9 mW at 1492.0 nm. The resulting pulses have a measured repetition rate and pulse width of 12.0-36.4 kHz and 6.2-3.6 μs, respectively. The maximum pulse energy that was achieved in this experiment is 122.8 nJ. To the author's knowledge, this is the first reported tunable passively Q-switched TFF laser that covers the S+/S region that has been demonstrated.

Patients with chronic dizziness following traumatic head injury typically have multiple diagnoses involving combined peripheral and central vestibular dysfunction

OBJECTIVE

We hypothesised that chronic vestibular symptoms (CVS) of imbalance and dizziness post-traumatic head injury (THI) may relate to: (i) the occurrence of multiple simultaneous vestibular diagnoses including both peripheral and central vestibular dysfunction in individual patients increasing the chance of missed diagnoses and suboptimal treatment; (ii) an impaired response to vestibular rehabilitation since the central mechanisms that mediate rehabilitation related brain plasticity may themselves be disrupted.

METHODS

We report the results of a retrospective analysis of both the comprehensive clinical and vestibular laboratory testing of 20 consecutive THI patients with prominent and persisting vestibular symptoms still present at least 6months post THI.

RESULTS

Individual THI patients typically had multiple vestibular diagnoses and unique to this group of vestibular patients, often displayed both peripheral and central vestibular dysfunction. Despite expert neuro-otological management, at two years 20% of patients still had persisting vestibular symptoms.

CONCLUSION

In summary, chronic vestibular dysfunction in THI could relate to: (i) the presence of multiple vestibular diagnoses, increasing the risk of 'missed' vestibular diagnoses leading to persisting symptoms; (ii) the impact of brain trauma which may impair brain plasticity mediated repair mechanisms. Apart from alerting physicians to the potential for multiple vestibular diagnoses in THI, future work to identify the specific deficits in brain function mediating poor recovery from post-THI vestibular dysfunction could provide the rationale for developing new therapy for head injury patients whose vestibular symptoms are resistant to treatment.

Functional neuroimaging of visuo-vestibular interaction

The brain combines visual, vestibular and proprioceptive information to distinguish between self- and world motion. Often these signals are complementary and indicate that the individual is moving or stationary with respect to the surroundings. However, conflicting visual motion and vestibular cues can lead to ambiguous or false sensations of motion. In this study, we used functional magnetic resonance imaging to explore human brain activation when visual and vestibular cues were either complementary or in conflict. We combined a horizontally moving optokinetic stimulus with caloric irrigation of the right ear to produce conditions where the vestibular activation and visual motion indicated the same (congruent) or opposite directions of self-motion (incongruent). Visuo-vestibular conflict was associated with increased activation in a network of brain regions including posterior insular and transverse temporal areas, cerebellar tonsil, cingulate and medial frontal gyri. In the congruent condition, there was increased activation in primary and secondary visual cortex. These findings suggest that when sensory information regarding self-motion is contradictory, there is preferential activation of multisensory vestibular areas to resolve this ambiguity. When cues are congruent, there is a bias towards visual cortical activation. The data support the view that a network of brain areas including the posterior insular cortex may play an important role in integrating and disambiguating visual and vestibular cues.