Channel Waveguides in Lithium Niobate and Lithium Tantalate.

Low-loss photonic waveguides in lithium niobate offer versatile functionality as nonlinear frequency converters, switches, and modulators for integrated optics. Combining the flexibility of laser processing with liquid phase epitaxy we have fabricated and characterized lithium niobate channel waveguides on lithium niobate and lithium tantalate. We used liquid phase epitaxy with K2O flux on laser-machined lithium niobate and lithium tantalate substrates. The laser-driven rapid-prototyping technique can be programmed to give machined features of various sizes, and liquid phase epitaxy produces high quality single-crystal, lithium niobate channels. The surface roughness of the lithium niobate channels on a lithium tantalate substrate was measured to be 90 nm. The lithium niobate channel waveguides exhibit propagation losses of 0.26 ± 0.04 dB/mm at a wavelength of 633 nm. Second harmonic generation at 980 nm was demonstrated using the channel waveguides, indicating that these waveguides retain their nonlinear optical properties.

Hormones in speed-dating: The role of testosterone and cortisol in attraction.

There is evidence that testosterone and cortisol levels are related to the attraction of a romantic partner; testosterone levels relate to a wide range of sexual behaviors and cortisol is a crucial component in the response to stress. To investigate this, we conducted a speed-dating study among heterosexual singles. We measured salivary testosterone and cortisol changes in men and women (n = 79) when they participated in a romantic condition (meeting opposite-sex others, i.e., potential romantic partners), as well as a control condition (meeting same-sex others, i.e., potential friends). Over the course of the romantic speed-dating event, results showed that women's but not men's testosterone levels increased and cortisol levels decreased for both men and women. These findings indicate that men's testosterone and cortisol levels were elevated in anticipation of the event, whereas for women, this appears to only be the case for cortisol. Concerning the relationship between attraction and hormonal change, four important findings can be distinguished. First, men were more popular when they arrived at the romantic speed-dating event with elevated cortisol levels. Second, in both men and women, a larger change in cortisol levels during romantic speed-dating was related to more selectivity. Third, testosterone alone was unrelated to any romantic speed-dating outcome (selectivity or popularity). However, fourth, women who arrived at the romantic speed-dating event with higher testosterone levels were more selective when their anticipatory cortisol response was low. Overall, our findings suggest that changes in the hormone cortisol may be stronger associated with the attraction of a romantic partner than testosterone.

2 W single-longitudinal-mode Yb:YAG distributed-feedback waveguide laser.

Single longitudinal mode (SLM) lasers are important tools for many scientific and commercial applications. SLM operation can be achieved in distributed-feedback (DFB) lasers based on Bragg structures. Semiconductor waveguide DFB lasers are well-established devices, but their output power is limited to a few hundred milliwatts. DFB lasers have also been demonstrated in dielectric waveguides. However, in this case the output power was even lower. Here we present the first monolithic Yb:YAG DFB laser. The waveguide and the DFB structure were fabricated in the volume of an Yb:YAG crystal by ultrafast laser inscription. The DFB laser delivered 2 W of output power at a slope efficiency of 61% in SLM operation under pumping with an optically pumped semiconductor laser. This power level outperforms previously demonstrated dielectric DFB waveguide lasers by nearly an order of magnitude. Our approach paves the way for compact, robust, and highly efficient high-power SLM laser sources.

On the electrification of road transportation - A review of the environmental, economic, and social performance of electric two-wheelers.

Electrification is widely considered as a viable strategy for reducing the oil dependency and environmental impacts of road transportation. In pursuit of this strategy, most attention has been paid to electric cars. However, substantial, yet untapped, potentials could be realized in urban areas through the large-scale introduction of electric two-wheelers. Here, we review the environmental, economic, and social performance of electric two-wheelers, demonstrating that these are generally more energy efficient and less polluting than conventionally-powered motor vehicles. Electric two-wheelers tend to decrease exposure to pollution as their environmental impacts largely result from vehicle production and electricity generation outside of urban areas. Our analysis suggests that the price of e-bikes has been decreasing at a learning rate of 8%. Despite price differentials of 5000 ± 1800 EUR2012 kW h-1 in Europe, e-bikes are penetrating the market because they appear to offer an apparent additional use value relative to bicycles. Mid-size and large electric two-wheelers do not offer such an additional use value compared to their conventional counterparts and constitute niche products at price differentials of 700 ± 360 EUR2012 kW-1 and 160 ± 90 EUR2012 kW-1, respectively. The large-scale adoption of electric two-wheelers can reduce traffic noise and road congestion but may necessitate adaptations of urban infrastructure and safety regulations. A case-specific assessment as part of an integrated urban mobility planning that accounts, e.g., for the local electricity mix, infrastructure characteristics, and mode-shift behavior, should be conducted before drawing conclusions about the sustainability impacts of electric two-wheelers.

In Vitro Effect of Enzymes and Human Milk Oligosaccharides on FODMAP Digestion and Fecal Microbiota Composition.

Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) cause intestinal discomfort in patients with irritable bowel syndrome (IBS). An enzyme mix (2500 SU invertase, 2400 GalU α-galactosidase, 10,000 ALU ß-galactosidase) optimized for FODMAP digestion, and/or human milk oligosaccharides (HMO) (2'-FL, DFL, and LNnT), were evaluated for effects on microbial community activity and composition in short-term colonic incubations using the fecal microbiota of four patients with IBS-D symptoms under the following test conditions: (i) FODMAP, (ii) pre-digested (with enzyme mix) FODMAP, (iii) FODMAP + HMO, and (iv) pre-digested FODMAP + HMO. Pre-digested FODMAP reduced short-chain fatty acid (SCFA) production versus FODMAP; HMO restored this. A 10-day experiment with the simulator of the human intestinal microbial ecosystem (SHIME®), using fecal samples from two patients with IBS-D, further evaluated these findings. FODMAP resulted in decreased microbial diversity versus blank. Pre-digestion with the enzyme mix restored microbial diversity, improved FODMAP digestibility, and reduced gas pressure versus undigested FODMAP; however, SCFA production decreased. HMO restored SCFA production along with an increase in gas pressure and increased abundance of Lachnospiraceae. When used in combination, the FODMAP enzyme mix and HMO may resolve FODMAP-related IBS symptoms while maintaining a healthy gut microbiome via prebiotic activity.

Ultrafast laser-written dual-wavelength waveguide laser.

We report the performance of a dual-wavelength waveguide laser based on a phase-modulated sampled-grating architecture fabricated using the femtosecond laser direct-write technique. The waveguide laser was written in Yb-doped phosphate glass and had a narrow linewidth (<10 pm), high signal-to-noise ratio (>60 dB), 5 mW output power per channel, and wavelength separation of 10 nm.

Genome sequencing and analysis of the versatile cell factory Aspergillus niger CBS 513.88.

The filamentous fungus Aspergillus niger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of the 14,165 open reading frames identified. A detailed description of the components of the protein secretion pathway was made and striking differences in the hydrolytic enzyme spectra of aspergilli were observed. A reconstructed metabolic network comprising 1,069 unique reactions illustrates the versatile metabolism of A. niger. Noteworthy is the large number of major facilitator superfamily transporters and fungal zinc binuclear cluster transcription factors, and the presence of putative gene clusters for fumonisin and ochratoxin A synthesis.

Laser written waveguide photonic quantum circuits.

We report photonic quantum circuits created using an ultrafast laser processing technique that is rapid, requires no lithographic mask and can be used to create three-dimensional networks of waveguide devices. We have characterized directional couplers--the key functional elements of photonic quantum circuits--and found that they perform as well as lithographically produced waveguide devices. We further demonstrate high-performance interferometers and an important multi-photon quantum interference phenomenon for the first time in integrated optics. This direct-write approach will enable the rapid development of sophisticated quantum optical circuits and their scaling into three-dimensions.

Lactose-Free Dairy Products: Market Developments, Production, Nutrition and Health Benefits.

Lactose-free dairy is able to provide the essential nutrients present in regular dairy products, like calcium and vitamins, to those that are not able to digest lactose. This product category currently has a wide and growing health appeal to consumers. In recent years, the quality and product variety in the lactose-free dairy segment has been increasing significantly, giving consumers more tempting products to decide from. As a result, lactose-free dairy is now the fastest growing market in the dairy industry. This review discusses the market developments and production possibilities and issues related to the wide variation of lactose-free dairy products that are currently available. Additionally, the health benefits that lactose-free dairy may offer compared to dairy avoidance are illustrated.

Femtosecond laser modification of fused silica: the effect of writing polarization on Si-O ring structure.

A femtosecond laser with a 1 kHz repetition rate and two different polarization states was used to fabricate low-loss waveguides in fused silica. Investigations of chemically-mechanically polished waveguide regions using near-field scanning optical microscopy revealed the presence of modifications outside the glass regions directly exposed to a circularly polarized writing laser. These waveguides also exhibited refractive index contrast up to twice as large as that of waveguides written with linearly polarized radiation. The observed differences in refractive index were shown by Raman spectroscopy to correlate to an increased concentration of 3-member silicon-oxygen ring structures. We propose that the observed differences in material properties are due to the polarization dependence of photo-ionization rates in fused silica.

Continuous-wave, intracavity doubled, self-Raman laser operation in Nd:GdVO(4) at 586.5 nm.

We report a continuous-wave self-Raman laser based on diode-pumped Nd:GdVO(4) giving first-Stokes output at 1173 nm and intracavity frequency-doubled output at 586.5 nm. A maximum cw output power at 1173 nm of 2 W was obtained for diode pump powers of 22 W and a maximum cw power at 586 nm of 678 mW with 16.3 W pump power. Infrared and yellow powers were limited by thermal lensing in the gain medium and parasitic oscillations of weak Nd(3+) transitions. Quasi-cw operation at 50% duty-cycle reduced the thermal load in the laser/Raman crystal, allowing cavity stability to be obtained near maximum available pump power (25.7 W) for which the maximum quasi-cw yellow output power was 1.88 W.

Energy exchange between two orthogonally polarized waves by cascading of two quasi-phase-matched quadratic processes.

We demonstrate energy exchange between two orthogonally polarized optical waves as a consequence of a two-color multistep parametric interaction. The energy exchange results from cascading of two quasi-phase-matched (QPM) second-harmonic parametric processes, and it is intrinsically instantaneous. The effect is observed when both the type-I (ooe) second-harmonic generation process and higher QPM order type-0 (eee) second-harmonic generation processes are phase-matched simultaneously in a congruent periodically-poled lithium niobate crystal. The two second-harmonic generation processes share a common second-harmonic wave which couple the two cross-polarized fundamental components and facilitate an energy flow between them. We demonstrate a good agreement between the experimental data and the results of numerical simulations.

Can images of pain enhance patient-clinician rapport in pain consultations?

A variety of treatment outcomes in chronic pain are influenced by patient-clinician rapport. Patients often report finding it difficult to explain their pain, and this potential obstacle to mutual understanding may impede patient-clinician rapport. Previous research has argued that the communication of both patients and clinicians is facilitated by the use of pain-related images in pain assessments. This study investigated whether introducing pain-related images into pain assessments would strengthen various components of patient-clinician rapport, including relative levels of affiliation and dominance, and interpersonal coordination between patient and clinician behaviour. Videos of 35 pain assessments in which pain images were present or absent were used to code behavioural displays of patient and clinician rapport at fixed intervals across the course of the assessment. Mixed modelling was used to examine patterns of patient and clinician affiliation and dominance with consultation type (Image vs Control) as a moderator. When pain images were present, clinicians showed more affiliation behaviour over the course of the consultation and there was greater correspondence between the affiliation behaviour of patient and clinician. However, relative levels of patient and clinician dominance were unaffected by the presence of pain images in consultations. Additional analyses revealed that clinicians responded directly to patients' use of pain images with displays of affiliation. Based on the results of this study, we recommend further investigation into the utility and feasibility of incorporating pain images into pain assessments to enhance patient-clinician communication.

Simultaneous phase matching and internal interference of two second-order nonlinear parametric processes.

We demonstrate the simultaneous generation and internal interference of two second-order parametric processes in a single nonlinear quadratic crystal. The two-frequency doubling processes are Type 0 (two extraordinary fundamental waves generate an extraordinary second-harmonic wave) and Type I (two ordinary fundamental waves generate an extraordinary second-harmonic wave) parametric interactions. The phase-matching conditions for both processes are satisfied in a single periodically poled grating in LiNbO3 using quasi-phase-matching (QPM) vectors with different orders. We observe an interference of two processes, and compare the results with the theoretical analysis. We suggest several applications of this effect such as polarization-independent frequency doubling and a method for stabilizing the level of the generated second-harmonic signal.

Extracellular prolyl endoprotease from Aspergillus niger and its use in the debittering of protein hydrolysates.

The observation that the bitterest peptides from casein hydrolysates contain several proline residues led us to hypothesize that a proline-specific protease would be instrumental in debittering such peptides. To identify the desired proline-specific activity, a microbiological screening was carried out in which the chromogenic peptide benzyloxycarbonyl-glycine-proline-p-nitroanilide (Z-Gly-Pro-pNA) was used as the substrate. An Aspergillus niger (A. niger) strain was identified that produces an extracellular proline-specific protease with an acidic pH optimum. On the basis of sequence similarities, we conclude that the A. niger-derived enzyme probably belongs to the S28 family of clan SC of serine proteases rather than the S9 family to which prolyl oligopeptidases belong. Incubating the overexpressed and purified enzyme with bitter casein hydrolysates showed a major debittering effect. Reversed phase HPLC analysis revealed that this debittering effect is accompanied by a significant reduction of the number of hydrophobic peptides present.

Characterisation of nonlinear conversion and crystal quality in Nd- and Yb-doped YAB.

Variable crystal quality affects the laser performance of many self-frequency doubling crystals, particularly those of the yttrium aluminum borate family. In this report we characterize nonlinear frequency conversion in Yb:YAB and demonstrate a simple non-destructive technique for measuring crystal quality. By imaging the nonlinear conversion using a CCD camera we observe phase matching characteristics similar to that obtained in quasi-phase-matched crystals. These effects are attributed to stacking faults in the structure of the YAB crystal during crystal growth. We believe that such defects cause the large variability in self-doubled performance reported for Nd- or Yb-doped YAB and that our technique may be used as a nondestructive measurement of crystal quality.

High repetition rate, q-switched and intracavity frequency doubled Nd:YVO(4) laser at 671nm.

Efficient intracavity frequency doubling of a q-switched, diode-pumped Nd:YVO(4) laser operating at 1342nm with pulse rates between 40 and 350kHz using type I critically phase matched LBO has been demonstrated. Maximum 671nm output power of 1.7W was obtained at 100kHz, with a diode to red conversion efficiency of 12%.

Efficient diode double-end-pumped Nd:YVO4 laser operating at 1342nm.

A Nd:YVO4 laser producing over 8W cw TEM00 at 1342nm with slope efficiency of 42% and optical to optical conversion efficiency of 33% has been demonstrated. Low neodymium doping concentration helps to reduce thermal loading in the laser crystal and increase achievable output power. While single end pumping approaches the crystal fracture limit, double-end-pumping effectively divides the thermal loading between the two ends of the laser crystal, allowing for reduced risk of fracture and greater power-scalability. Intracavity frequency doubling in LBO generated cw output powers over 900mW at 671nm.

Impact of pain behaviors on evaluations of warmth and competence.

This study investigated the social judgments that are made about people who appear to be in pain. Fifty-six participants viewed 2 video clips of human figures exercising. The videos were created by a motion tracking system, and showed dots that had been placed at various points on the body, so that body motion was the only visible cue. One of the figures displayed pain behaviors (eg, rubbing, holding, hesitating), while the other did not. Without any other information about the person in each video, participants evaluated each person on a variety of attributes associated with interpersonal warmth, competence, mood, and physical fitness. As well as judging them to be in more pain, participants evaluated the person who displayed pain behavior as less warm and less competent than the person who did not display pain behavior. In addition, the person who displayed pain behavior was perceived to be in a more negative mood and to have poorer physical fitness than the person who did not, and these perceptions contributed to the impact of pain behaviors on evaluations of warmth and competence, respectively. The implications of these negative social evaluations for social relationships, well-being, and pain assessment in persons in chronic pain are discussed.

Interaction of flavan-3-ol derivatives and different caseins is determined by more than proline content and number of proline repeats.

Interactions of Type A and B flavan-3-ol dimers (procyanidins) and several monomeric flavan-3-ols, with α-casein and ß-casein, were investigated. Binding affinities measured were related to the ligands structure, including several properties (e.g. intrinsic flexibility (number of rotatable bonds) and hydrophobicity), and to the amino-acid composition of the caseins. A monomeric flavan-3-ol esterified with gallic acid (EGCG) had a five to ten times higher affinity to caseins compared to the non-galloylated dimeric flavan-3-ols. In this case, the larger number of rotatable bonds in EGCG might be accountable for this difference. Comparing flavan-3-ol dimers, intrinsic flexibility did not consistently promote interactions, as procyanidin A1 displayed a higher affinity to α-casein than the supposedly more flexible B-type dimers investigated. Despite its higher content of proline, compared to α-casein, ß-casein did not always have a higher affinity for the ligands investigated (e.g. no interaction with procyanidin A1 detected). These results suggest that more factors than proline content and the number of proline repeats govern phenolic-casein interactions.