Bench testing of a heterodyne CO2 laser dispersion interferometer for high temporal resolution plasma density measurements

A heterodyne detection scheme is combined with a 10.59 μm CO₂ laser dispersion interferometer for the first time to allow large bandwidth measurements in the 10-100 MHz range. The approach employed utilizes a 40 MHz acousto-optic cell operating on the frequency doubled CO₂ beam which is obtained using a high 2nd harmonic conversion efficiency orientation patterned gallium arsenide crystal. The measured standard deviation of the line integrated electron density equivalent phase resolution obtained with digital phase demodulation technique, is 4 × 10¹⁷ m^-2. Air flow was found to significantly affect the baseline of the phase signal, which an optical table cover was able to reduce considerably. The heterodyne dispersion interferometer (DI) approach is found to be robustly insensitive to motion, with measured phase shifts below baseline drifts even in the presence of several centimeters of retroreflector induced path length variations. Plasma induced dispersion was simulated with a wedged ZnSe plate and the measured DI phase shifts are consistent with expectations.

Design of a dispersion interferometer combined with a polarimeter to increase the electron density measurement reliability on ITER

A dispersion interferometer is a reliable density measurement system and is being designed as a complementary density diagnostic on ITER. The dispersion interferometer is inherently insensitive to mechanical vibrations, and a combined polarimeter with the same line of sight can correct fringe jump errors. A proof of the principle of the CO₂ laser dispersion interferometer combined with the PEM polarimeter was recently conducted, where the phase shift and the polarization angle were successfully measured simultaneously. Standard deviations of the line-average density and the polarization angle measurements over 1 s are 9 × 10¹⁶ m^-2 and 0.19°, respectively, with a time constant of 100 μs. Drifts of the zero point, which determine the resolution in steady-state operation, correspond to 0.25% and 1% of the phase shift and the Faraday rotation angle expected on ITER.

Asymptomatic malaria, growth status, and anaemia among children in Lao People's Democratic Republic: a cross-sectional study

Background

Asymptomatic malaria can be observed in both stable endemic areas and unstable transmission areas. However, although much attention has been given to acute malaria infections, relatively little attention has been paid to asymptomatic malaria. Nonetheless, because the asymptomatic host serves as a reservoir for the malaria parasite, asymptomatic malaria is now recognized as an important obstacle to malaria elimination. Asymptomatic malaria is also associated with anaemia, a global public health problem with serious consequences on human health as well as social and economic development. In Lao People’s Democratic Republic (Lao PDR), malaria, anaemia, and malnutrition are serious public health concerns. However, few studies have focused on the relationship between these variables. Therefore, this study investigated the relationship between asymptomatic malaria, growth status, and the prevalence of anaemia among children aged 120 months old or younger in rural villages in Lao PDR.

Methods

In December 2010 and March 2011, data were collected from five villages in Savannakhet province. Anthropometric measurements, blood samples, and malaria rapid diagnostic tests were conducted. The presence of malaria was confirmed with polymerase chain reaction assays for Plasmodium falciparum. Underweight status, stunting, and anaemia were defined according to World Health Organization standards.

Results

The mean age of participants (n = 319) was 88.3 months old (Standard Deviation: 20.6, ranged from 30–119 months old), and 20 participants (6.3 %) had an asymptomatic malaria infection, 92 (28.8 %) were anaemic, 123 (38.6 %) were underweight, and 137 (42.9 %) were stunted. Stunted children were more likely to be infected with asymptomatic malaria [odds ratio (OR) 3.34, 95 % confidence interval (CI) 1.25–8.93], and asymptomatic malaria was associated with anaemia [OR 5.17, 95 % CI 1.99–13.43].

Conclusions

These results suggest a significant association between asymptomatic malaria and anaemia in children. Furthermore, stunted children were more likely to have lower Hb levels and to be infected with asymptomatic malaria than children without stunting. However, further studies examining the impact of asymptomatic malaria infection on children’s nutritional and development status are necessary.

Intradermal endothelin-1 excites bombesin-responsive superficial dorsal horn neurons in the mouse

Endothelin-1 (ET-1) has been implicated in nonhistaminergic itch. Here we used electrophysiological methods to investigate whether mouse superficial dorsal horn neurons respond to intradermal (id) injection of ET-1 and whether ET-1-sensitive neurons additionally respond to other pruritic and algesic stimuli or spinal superfusion of bombesin, a homolog of gastrin-releasing peptide (GRP) that excites spinal itch-signaling neurons. Single-unit recordings were made from lumbar dorsal horn neurons in pentobarbital-anesthetized C57BL/6 mice. We searched for units that exhibited elevated firing after id injection of ET-1 (1 μg/μl). Responsive units were further tested with mechanical stimuli, bombesin (spinal superfusion, 200 μg·ml(-1)·min(-1)), heating, cooling, and additional chemicals [histamine, chloroquine, allyl isothiocyanate (AITC), capsaicin]. Of 40 ET-1-responsive units, 48% responded to brush and pinch [wide dynamic range (WDR)] and 52% to pinch only [high threshold (HT)]. Ninety-three percent responded to noxious heat, 50% to cooling, and >70% to histamine, chloroquine, AITC, and capsaicin. Fifty-seven percent responded to bombesin, suggesting that they participate in spinal itch transmission. That most ET-1-sensitive spinal neurons also responded to pruritic and algesic stimuli is consistent with previous studies of pruritogen-responsive dorsal horn neurons. We previously hypothesized that pruritogen-sensitive neurons signal itch. The observation that ET-1 activates nociceptive neurons suggests that both itch and pain signals may be generated by ET-1 to result in simultaneous sensations of itch and pain, consistent with observations that ET-1 elicits both itch- and pain-related behaviors in animals and burning itch sensations in humans.

Electric-field-induced modification of the magnon energy, exchange interaction, and curie temperature of transition-metal thin films

The electric-field-induced modification in the Curie temperature of prototypical transition-metal thin films with the perpendicular magnetic easy axis, a freestanding Fe(001) monolayer and a Co monolayer on Pt(111), is investigated by first-principles calculations of spin-spiral structures in an external electric field (E field). An applied E field is found to modify the magnon (spin-spiral formation) energy; the change arises from the E-field-induced screening charge density in the spin-spiral states due to p-d hybridizations. The Heisenberg exchange parameters obtained from the magnon energy suggest an E-field-induced modification of the Curie temperature, which is demonstrated via Monte Carlo simulations that take the magnetocrystalline anisotropy into account.

The orthopaedic research scene and strategies to improve it

Trauma and orthopaedics is the largest of the surgical specialties and yet attracts a disproportionately small fraction of available national and international funding for health research. With the burden of musculoskeletal disease increasing, high-quality research is required to improve the evidence base for orthopaedic practice. Using the current research landscape in the United Kingdom as an example, but also addressing the international perspective, we highlight the issues surrounding poor levels of research funding in trauma and orthopaedics and indicate avenues for improving the impact and success of surgical musculoskeletal research.

Excess NF-κB induces ectopic odontogenesis in embryonic incisor epithelium

Nuclear factor kappa B (NF-κB) signaling plays critical roles in many physiological and pathological processes, including regulating organogenesis. Down-regulation of NF-κB signaling during development results in hypohidrotic ectodermal dysplasia. The roles of NF-κB signaling in tooth development, however, are not fully understood. We examined mice overexpressing IKKβ, an essential component of the NF-κB pathway, under keratin 5 promoter (K5-Ikkβ). K5-Ikkβ mice showed supernumerary incisors whose formation was accompanied by up-regulation of canonical Wnt signaling. Apoptosis that is normally observed in wild-type incisor epithelium was reduced in K5-Ikkβ mice. The supernumerary incisors in K5-Ikkβ mice were found to phenocopy extra incisors in mice with mutations of Wnt inhibitor, Wise. Excess NF-κB activity thus induces an ectopic odontogenesis program that is usually suppressed under physiological conditions.

Dispersion interferometer using modulation amplitudes on LHD (invited)

Since a dispersion interferometer is insensitive to mechanical vibrations, a vibration compensation system is not necessary. The CO2 laser dispersion interferometer with phase modulations on the Large Helical Device utilizes the new phase extraction method which uses modulation amplitudes and can improve a disadvantage of the original dispersion interferometer: measurement errors caused by variations of detected intensities. The phase variation within ±2 × 10(17) m(-3) is obtained without vibration compensation system. The measured line averaged electron density with the dispersion interferometer shows good agreement with that with the existing far infrared laser interferometer. Fringe jump errors in high density ranging up to 1.5 × 10(20) m(-3) can be overcome by a sufficient sampling rate of about 100 kHz.

Factors influencing the National School Health Policy implementation in Lao PDR: a multi-level case study

In the last decade, a National School Health Policy (NSHP) has been formulated in several developing countries following the recommendations of the Global School Health Initiative. However, NSHP implementations across the country have not been fully shared. This study aimed to identify factors that have influenced implementation of the NSHP in Lao People's Democratic Republic (Lao PDR). We conducted key informant interviews with 20 NSHP implementers and document reviews. Data were collected at the national level and at three lower administrative levels (provincial, district and school) in three areas (north, central and south). Study areas were selected according to the history of NSHP interventions. We applied content analysis using 12 key components of successful policy implementation and a policy triangle framework. We found that scaling up to nationwide implementation was limited. Results showed the NSHP implementation in Lao PDR was influenced by nine interlinked factors, including extensive planning, resource management, monitoring cycle, the perception gap between national and lower administrative officers, national task-force ownership, ongoing coaching of district educational officers, management skills of school principals, priority of school health and decentralization. Furthermore, these nine factors could be integrated into the existing educational system. In conclusion, for sustainable and nationwide implementation of the NSHP in Lao PDR, the following three factors need to be embedded in the educational system: extensive planning with a clear long-term vision at national level, human resource management including well-organized training at each administrative level and a monitoring cycle to understand the real situation at school level.

Contribution of calpain to myoglobin efflux from cardiomyocytes during ischaemia and after reperfusion in anaesthetized rats

AIM

Calpain activation has a putative role in ischaemia-reperfusion injury of cardiomyocytes. This study clarified the in vivo contribution of calpain to disruption of cardiomyocyte sarcolemma during ischaemia and after reperfusion in anaesthetized rats.

METHODS

Using a microdialysis technique in the hearts of anaesthetized rats, we investigated the effects of the calpain inhibitors on myocardial interstitial myoglobin level in the ischaemic region during coronary occlusion and after reperfusion. The calpain inhibitors were administered locally via a dialysis probe. Two durations of coronary occlusion were tested.

RESULTS

Thirty-minute coronary occlusion: dialysate myoglobin concentration increased markedly from 385 ± 46 ng mL(-1) at baseline to 3701 ± 527 ng mL(-1) at 20-30 min of occlusion. After reperfusion, dialysate myoglobin concentration further increased, reaching a peak (12 296 ± 1564 ng mL(-1) ) at 10-20 min post-reperfusion and then declined gradually. The calpain inhibitors, MDL-28170 and SNJ-1945 did not change dialysate myoglobin concentration during occlusion but attenuated the increase after reperfusion to 6826 ± 1227 and 8130 ± 938 ng mL(-1) at 10-20 min post-reperfusion (P < 0.05), respectively. Ninety-minute coronary occlusion: dialysate myoglobin concentration increased from 516 ± 33 ng mL(-1) at baseline to 5463 ± 387 ng mL(-1) at 80-90 min after occlusion. After reperfusion, there was no significant increase in dialysate myoglobin concentration. MDL-28170 did not affect dialysate myoglobin concentration during occlusion or after reperfusion.

CONCLUSION

Calpain contributes to sarcolemmal disruption immediately after reperfusion following 30-min coronary occlusion, but has little effects during ischaemia and after reperfusion in 90-min coronary occlusion.

Behavioral model of itch, alloknesis, pain and allodynia in the lower hindlimb and correlative responses of lumbar dorsal horn neurons in the mouse

We have further developed a behavioral model of itch and pain in the lower hindlimb (calf) originally reported by LaMotte et al. (2011) that allows comparisons with responses of lumbar dorsal horn neurons to pruritic and noxious stimuli. Intradermal (id) microinjection of the pruritogens histamine, SLIGRL-NH2 (agonist of PAR-2 and MrgprC11) and chloroquine (agonist of MrgprA3) into the calf of the lower limb elicited significant biting and a small amount of licking directed to the injection site, over a 30-min time course. Following id injection of histamine, low-threshold mechanical stimuli reliably elicited discrete episodes of biting (alloknesis) over a longer time course; significantly less alloknesis was observed following id injection of SLIGRL-NH2. Capsaicin injections elicited licking but little biting. Following id injection of capsaicin, low-threshold mechanical stimuli elicited discrete hindlimb flinches (allodynia) over a prolonged (>2h) time course. In single-unit recordings from superficial lumbar dorsal horn neurons, low-threshold mechanically evoked responses were significantly enhanced, accompanied by receptive field expansion, following id injection of histamine in histamine-responsive neurons. This was not observed in histamine-insensitive neurons, or following id injection of saline or SLIGRL-NH2, regardless of whether the latter activated the neuron or not. These results suggest that itch-responsive neurons are selectively sensitized by histamine but not SLIGRL-NH2 to account for alloknesis. The presently described "calf" model appears to distinguish between itch- and pain-related behavioral responses, and provides a basis to investigate lumbar spinal neural mechanisms underlying itch, alloknesis, pain and allodynia.

Self-assessed approach to improving school health in Niger

INTRODUCTION

Award schemes and self-evaluation systems have been developed to implement the 'Health-Promoting School (HPS)' concept in European and Asian countries. While there have been many successes in these regions, the implementation of HPS in African countries has been minimal. This study evaluated the impact of a self-evaluation system on school health in Niger.

METHODS

A school health activity guide was developed and distributed to 1999 primary schools in the Niger Tahoua region to raise awareness and solve problems related to school health and hygiene. The number of schools that planned or implemented health-related activities, and the budget and implementation status of their activities was compared over 3 years (before, soon after, and 1 year after distribution). Focus group discussions (FGDs) were also conducted targeting Conseillers Pédagogiques (CPs), who supervise primary schools and teachers, primary school principals and members of Comité de Gestion des Etablissement Scolaire (COGES), which is a type of school steering committee.

RESULTS

The number of schools planning at least one health-related activity increased from 47% to 79% soon after distribution of the guide (p <0.001).The number of schools implementing activities increased from 44% to 65% one year after distribution (p <0.001). Health-related budget per school also increased after distribution (p <0.0001) and increases were maintained 1 year after the intervention (p=0.8414). Fulfilment or partial fulfilment rates for health-related activities were lower compared with other (non-health) activities in all three years (80%, 77% & 84% in health-related activities vs 88%, 90% & 91% in others; p <0.001, p <0.001, & p=0.004, respectively). Most FGD participants expressed a positive impression of the program and noted the usefulness of the guide. However, some respondents reported difficulties, especially in relation to budget.

CONCLUSION

The introduction of a health activity guide for self-assessment was effective in increasing health-related activities in primary schools in Niger, where a simple monitoring system should be introduced to establish the HPS concept.

Sympathetic afferent stimulation inhibits central vagal activation induced by intravenous medetomidine in rats

AIM

To examine whether sympathetic afferent stimulation (SAS) inhibits central vagal activation induced by α2 -adrenergic stimulation.

METHODS

In anaesthetized Wistar-Kyoto rats, a cardiac microdialysis technique was applied to the left ventricle, and the effect of α2 -adrenergic stimulation by medetomidine on myocardial interstitial acetylcholine (ACh) levels was examined in the absence (n = 6) or the presence (n = 6) of SAS delivered from the left stellate ganglion. The effect of electrical vagal efferent stimulation on myocardial interstitial ACh release was also examined in the absence or the presence of SAS (n = 6).

RESULTS

Intravenous medetomidine (0.1 mg kg(-1) ) significantly increased myocardial interstitial ACh levels in the absence of SAS (from 1.95 ± 0.79 to 3.36 ± 1.61 nM, P < 0.05), but not in the presence of SAS (from 1.67 ± 0.67 to 2.01 ± 0.78 nM). In contrast, electrical vagal nerve stimulation increased myocardial interstitial ACh level to the same degree regardless of SAS (from 1.66 ± 0.16 to 3.93 ± 0.72 nM without SAS vs. 4.05 ± 0.89 nM with SAS).

CONCLUSION

Sympathetic afferent stimulation inhibited medetomidine-induced ACh release, but not electrical stimulation-induced ACh release, suggesting that SAS inhibited medetomidine-induced vagal activation via central mechanisms. While central vagal activation by α2 -adrenergic agonists could be an alternative to electrical vagal activation, blocking sympathetic afferent input may be important to increase the efficacy of α2 -adrenergic agonists in enhancing vagal nerve activity.

Geographical characterization of the triatomine infestations in north–central Guatemala

In an entomological study in 2002, the degree of domestic and peridomestic infestation with triatomine bugs and the geographical distribution of such infestations were investigated in north-central Guatemala. The survey team searched for triatomines in houses constructed with mud walls or thatched roofs, in villages suspected of being infested. The level of infestation observed was lower than that seen in the same area and in eastern Guatemala, in a preliminary survey, 3 years earlier. Most of the infestations detected were of Triatoma dimidiata but even this species was found in <7% of the houses investigated. Infestations with Rhodnius prolixus or other potential vectors of Trypanosoma cruzi were much rarer. The generally low levels of infestation make the elimination of R. prolixus and the reduction of the domestic population of Tri. dimidiata feasible in the study area. The southern part of the study area had higher levels of domestic infestation and colonization than the north, and peridomestic infestation was highest in the south-west. Given such geographical variation in the pattern of infestation, it would seem wise to stratify the study region into areas of high, moderate and low-risk of human-triatomine contact, so that appropriate vector-control strategies can be targeted at the worst-affected areas. Regular entomological surveillance, ideally with community participation, is recommended. Analysis of the relationship between the geographical patterns of infestation and factors such as vegetation, altitude and vector migration would be useful.

Scratching inhibits serotonin-evoked responses of rat dorsal horn neurons in a site- and state-dependent manner

Scratching inhibits pruritogen-evoked responses of neurons in the superficial dorsal horn, implicating a spinal site for scratch inhibition of itch. We investigated if scratching differentially affects neurons depending on whether they are activated by itchy vs. painful stimuli, and if the degree of inhibition depends on the relative location of scratching. We recorded from rat lumbar dorsal horn neurons responsive to intradermal (id) microinjection of serotonin (5-hydroxytryptamine, 5-HT). During the response to 5-HT, scratch stimuli (3mm, 300 mN, 2 Hz, 20s) were delivered at the injection site within the mechanosensitive receptive field (on-site), or 4-30 mm away, outside of the receptive field (off-site). During off-site scratching, 5-HT-evoked firing was significantly attenuated followed by recovery. On-site scratching excited neurons, followed by a significant post-scratch decrease in 5-HT-evoked firing. Most neurons additionally responded to mustard oil (allyl isothiocyanate). Off-site scratching had no effect, while on-site scratching excited the neurons. These results indicate that scratching exerts a state-dependent inhibitory effect on responses of spinal neurons to pruritic but not algesic stimuli. Moreover, on-site scratching first excited neurons followed by inhibition, while off-site scratching immediately evoked the inhibition of pruritogen-evoked activity. This accounts for the suppression of itch by scratching at a distance from the site of the itchy stimulus.

Atomic-layer alignment tuning for giant perpendicular magnetocrystalline anisotropy of 3d transition-metal thin films

The magnetocrystalline anisotropy (MA) of Fe-based transition-metal thin films, consisting of only magnetic 3d elements, was systematically investigated from full-potential linearized augmented plane-wave calculations. The results predict that giant MA with a perpendicular magnetic easy axis (PMA) can be achieved by tuning the atomic-layer alignments in an Fe-Ni thin film. This giant PMA arises from the spin-orbit coupling interaction between occupied and unoccupied Ni dx2-y2,xy bands crossing the Fermi level. A promising 3d transition-metal thin film for the MgO-based magnetic tunnel junctions with the giant PMA was, thus, demonstrated.

Association between serum zinc concentration and the Plasmodium falciparum antibody titer among rural villagers of Attapeu Province, Lao People's Democratic Republic

Experimental studies have indicated that low serum zinc levels affect immune responses. However, few studies have evaluated the impact of serum zinc levels on antibody responses in the field in developing countries. We investigated an association between the anti-Plasmodium falciparum (Pf) antibody (immunoglobulin G) titer and serum zinc concentration among villagers in rural areas of the Lao People's Democratic Republic. Blood samples were collected to detect Pf infection. An enzyme-linked immunosorbent assay (ELISA) was used to measure the anti-PfIgG antibody titer. Each serum sample was assayed to measure the concentration of zinc. Pearson's correlation coefficient was applied to the association between zinc concentration and anti-PfIgG antibody titers. Multiple linear regression analysis was used to assess the association between zinc concentration and anti-PfIgG antibody titers, controlling for age and albumin level. Of 71 blood samples, 40 were Pf positive and 31 were Pf negative. The median serum zinc concentrations were 56.0 μg/dl in the Pf-positive group and 62.5 μg/dl in the Pf-negative group. The median anti-Pf titers were 833.4 in the positive group and 1237.2 in the negative group. Unexpectedly, there was a negative correlation between serum zinc and anti-Pf IgG antibody titers; the correlation coefficient were -0.453 and (p=0.003) in the positive group and -0.461 (p=0.009) in the negative group. The results of this study indicated sustained antibody responses among the villagers, who had likely been exposed to malaria periodically throughout their lives. Further studies are necessary to determine the conditions in which zinc could be effective against malaria.

Magnetism and multiplets in metal-phthalocyanine molecules

Magnetism and multiplets for metal-phthalocyanine (MPc) molecules with transition-metals (M) of Mn and Co were investigated based on the constraint density functional theory calculations by imposing density matrix constraint on the d-orbital occupation numbers. For the MnPc, the ground state is found to be the 4Eg state with the perpendicular magnetic anisotropy with respect to the molecular plane, while for the CoPc, the ground state is the 2A1g state with a planar magnetic anisotropy.