Hierarchical self-assembling and helical structure in focal conic domains in meniscus of ferroelectric liquid crystal.

We investigate experimentally the formation of focal conic domains of the ferroelectric phase of a liquid crystal, chiral smectic C (SmC^{*}), in the meniscus geometry. The meniscus geometry is formed in the gap between two glass plates which are placed on a common substrate. This gap is called here a physical cavity. Focal conic domains (FCDs) in the physical cavity with dimensions of micrometer scale are investigated under an optical polarizing microscope which enables us to extract the information on the helical structure formation in the constraint and gradient topological meniscus interface. The helical pitch in the FCD is observed to be shorter than in planar confined geometry. A crucial phenomenon of unwrapping and wrapping of helical structure from one FCD to another is also observed. In-plane application of an electric field on a FCD revealed the asymmetric helical unwinding process whereas an increase in temperature has shown symmetrical unwinding. The helical structure based observation is significant for understanding the ferroelectric phase in focal conic domains and their application in microlenses and optical components.

Structure and genetic diversity of natural populations of Morus alba in the trans-Himalayan Ladakh region.

Sequence-related amplified polymorphism markers were used to assess the genetic structure in three natural populations of Morus alba from trans-Himalaya. Multilocation sampling was conducted across 14 collection sites. The overall genetic diversity estimates were high: percentage polymorphic loci 89.66%, Nei's gene diversity 0.2286, and Shannon's information index 0.2175. At a regional level, partitioning of variability assessed using analysis of molecular variance (AMOVA), revealed 80% variation within and 20% among collection sites. Pattern appeared in STRUCTURE, BARRIER, and AMOVA, clearly demonstrating gene flow between the Indus and Suru populations and a geographic barrier between the Indus-Suru and Nubra populations, which effectively hinders gene flow. The results showed significant genetic differentiation, population structure, high to restricted gene flow, and high genetic diversity. The assumption that samples collected from the three valleys represent three different populations does not hold true. The fragmentation present in trans-Himalaya was more natural and less anthropogenic.

Trapezius squeeze test as an indicator for depth of anesthesia for laryngeal mask airway insertion in children.

BACKGROUND: Clinical tests, such as loss of verbal contact, eyelash reflex, corneal reflex, and jaw relaxation, are used to assess the depth of anesthesia. "Trapezius squeeze test" (TST) is one such clinical test. It is a simple test to perform in which 1-2 inches of trapezius muscle is held and squeezed in full thickness and response is evaluated in the form of toe/body movement. MATERIALS AND METHODS: One hundred pediatric patients between 3 and 5 years of age, scheduled to undergo elective surgery, were included in this study. We evaluated negative TST as an indicator for optimal anesthesia depth for laryngeal mask airway (LMA) insertion in anesthetized spontaneously breathing children. Anesthesia was induced using 4% sevoflurane in oxygen. As the child lost the verbal contact or loss of body movement, TST was performed. Test was repeated every 15 s till it became negative. When the TST became negative, a well lubricated, appropriate-size LMA was inserted. RESULTS: Mean time for TST to become negative in our study was 271.80 ± 55.8 s and ease of insertion was excellent in 91 patients and acceptable in 9 patients. LMA was successfully inserted in first attempt in 96% patients. CONCLUSIONS: Negative TST is a reliable indicator for placement of LMA in spontaneously breathing children. Excellent conditions for LMA placement are present in majority of the patients without any untoward effects at this point of time.

Optical memory effect in a deformed helix ferroelectric liquid crystal.

Optical memory in a deformed-helix ferroelectric liquid crystal is proposed by deforming the helix under the application of a square-voltage pulse of known magnitude and frequency. This effect is based on the electromechanical effect of helix deformation due to the electric field. When the interaction between the electric field and the dipole is sufficiently strong, all of the dipoles align along the electric field. In such a situation the interlayer dipole-dipole interaction is strong enough to balance the elastic deformation energy. When the electric field is switched off, the molecules remain in a static, balanced state owing to the dipole-dipole interaction and hence the memory effect.

Posterior fossa oligodendroglioma.

Oligodendroglioma are the tumors of glial cells. They are rare in children and are more common in the cerebral hemispheres. A rare case of infratentorial oligodendroglioma in a female child is being reported here.