Comment on "Orientational Distribution of Free O-H Groups of Interfacial Water is Exponential"

In a recent letter (PRL,121,246101,2018), Sun et al. reported that combined MD simulation and sum frequency generation vibrational spectroscopy (SFG-VS) measurements led to conclusions of a broad and exponentially decaying orientational distribution, and the presence of the free O-H group pointing down to the bulk at the air/water interface. In this comment, we show that their main conclusions are based on questionable interpretation of the SFG-VS data presented in the letter [1], and are also contrary to the established data analysis and interpretations in the literature [2-5].Comment: 2 pages, 0 figure

A statistical approach towards performance analysis of multimodal biometrics systems

Fueled by recent government mandates to deliver public functions by the use of biometrics, multimodal biometrics authentication has made rapid progress over the past a few years. Performance of multimodal biometrics systems plays a crucial role in government applications, including public security and forensic analysis. However, current performance analysis is conducted without considering the influence of noises, which may result in unreliable analytical results when noise levels change in practice. This thesis investigates the application of statistical methods in performance analysis of multimodal biometric systems. It develops an efficient and systematic approach to evaluate system performance in different situations of noise influences. Using this approach, 126 experiments are conducted with the BSSR1 dataset. The proposed approach helps to examine the performance of typical fusion methods that use different normalization and data partitioning techniques. Experiment results demonstrate that the Simple Sum fusion method working with the Min-Max normalization and Re-Substitution data partitioning yields the best overall performance in different noise conditions. In addition, further examination of the results reveals the need of systematic analysis of system performance as the performance of some fusion methods exhibits big variations when the level of noises changes and some fusion methods may produce very good performance in some application though normally unacceptable in others

Quantification of appetite-regulating hormones in children with hypothalamic and common obesity

Background. Current understanding of the appetite-regulating neuroendocrine circuitry remains incomplete, and efficacious treatments for both common and hypothalamic obesity (HyOb) are lacking. Concurrently, the expanded role of oxytocin (OXT) in energy homeostasis and human behaviour is beginning to be understood. Objectives. To optimise and translate an OXT enzyme immunoassay (EIA) to elucidate whether there were any unique differences in the plasma endocrine milieu in patients with HyOb. Methods. Optimisation work was carried out using EIAs with polyclonal and monoclonal secondary antibodies. Obese (BMI>+2 SDS) and lean (BMI≤+2 SDS) children with (HyOb and HyLean) and without (Ob and Lean) hypothalamic disorders (septo-optic dysplasia or suprasellar tumours) were phenotyped using the Dykens’ Hyperphagia Questionnaire Score (DHQS). Plasma concentrations of leptin, insulin, OXT, BDNF, αMSH, acylated ghrelin, AgRP and copeptin were measured. Results. Solid phase extraction demonstrated markedly variable OXT recovery, and potentially increased rather than decreased interference. A polyclonal secondary antibody-containing EIA showed significant cross-reactivity with several peptides in human plasma compared to a monoclonal secondary antibody-containing EIA. Of the 122 children recruited (50 HyOb, 29 HyLean, 24 Ob, 19 Lean, mean age 11.3±3.9 years) there were no differences in DHQS or hormone concentrations between HyOb and Ob groups. Obesity was associated with compensatorily increased leptin and insulin, and decreased ghrelin and AgRP concentrations. More rapidly increasing BMI was independently associated with a younger age and lower plasma αMSH concentrations. OXT concentrations did not show any correlation with BMI or DHQS. Conclusion. The use of plasma extraction processes and EIAs in the literature needs re-examination. The plasma endocrine milieu in HyOb vs. common obesity does not differ, with a compensatory increase in anorexigens and decrease in orexigens. Lower plasma αMSH was associated with more rapid weight gain, suggesting that MC4R agonists may be a therapeutic option in all forms of obesity