Nanoscale virtual potentials using optical tweezers

We combine optical tweezers with feedback to impose arbitrary potentials on a colloidal particle. The feedback trap detects a particle's position, calculates a force based on an imposed "virtual potential," and shifts the trap center to generate the desired force. We create virtual harmonic and double-well potentials to manipulate particles. The harmonic potentials can be chosen to be either weaker or stiffer than the underlying optical trap. Using this flexibility, we create an isotropic trap in three dimensions. Finally, we show that we can create a virtual double-well potential with fixed well separation and adjustable barrier height. These are accomplished at length scales down to 11 nm, a feat that is difficult or impossible to create with standard optical-tweezer techniques such as time sharing, dual beams, or spatial light modulators

Ethnomedicines of Tharu Tribes of Dudhwa National Park, India

Ethnomedicines play an important role in the healthcare practices of the Tharu tribes of Dudhwa National Park. A study was conducted to document their ethnomedicine and identify potential species for phytochemical and pharmacological studies. Fieldwork was conducted over a period of two years in Dudhwa National Park, utilizing the “transect walk” method of Participatory Rural Appraisal (PRA). The data was analyzed using frequency of citation and informant consensus factor (FIC). This research details 95 species of medicinal plants and 97 ethnomedicines used in the treatment of 49 ailments of humans. The ailments are categorized into 14 categories (symptoms/similarities, etc). The FIC values indicate that there was a high degree of consensus among informants on how to treat injuries, respiratory ailments, circulatory system ailments, digestive disorders, colds, and fevers. The most useful medicinal species, ranked according to their perceived FIC were: Moringa oleifera Lam. (high blood pressure), Piper longum L. (cough), Nicotiana tabacum L. (dermatitis/skin itching), Cleome viscosa L. (boil), Ceriscoides turgida (Roxb.) Tirveng. (stomach ulcer), Lawsonia inermis L. (dysentery), Cissampelos pareira L. (stomachache), Andrographis paniculata (Burm. f.) Nees (fever, anorexia), Tamilnadia uliginosa (Retz.) Tirveng. & Sastre (dysentery), and Tridax procumbens (L.) L. (nocturnal emission). In remedy preparations, the leaves were the most frequently used plant part (33 instances), and most of the preparations were in the form of extraction or juice. Herbs were the most frequently used source of medicine (48%), followed by trees (23%) and shrubs (17%). A total of 34 medicinal claims were new to ethnomedicine of India. Those plants which received high citation frequency may prove useful for pharmacological studies in new drug development projects