The importance of loop length on the stability of i-motif structures

Using UV and srCD spectroscopy it is found that loop length within the i-motif structure is important for both thermal and pH stability, but in contrast to previous statements, it is the shorter loops that exhibit the highest stability.

Assessment of variations of the mandibular canal through cone beam computed tomography

The neurovascular bundle may be vulnerable during surgical procedures involving the mandible, especially when anatomical variations are present. Increased demand of implant surgeries, wider availability of three-dimensional exams, and lack of clear definitions in the literature indicate that features of anatomical variations should be revisited. The objective of the study was to evaluate features of anatomical variations related to mandibular canal (MC), such as bifid canals, anterior loop of mental nerve, and corticalization of MC. Additionally, bone trabeculation at the submandibular gland fossa region (SGF) was assessed and related to visibility of MC. Cone beam computed tomography exams from 100 patients (200 hemimandibles) were analyzed and the following parameters were registered: diameter and corticalization of MC; trabeculation in SGF region; presence of bifid MC, position of bifurcations, diameter, and direction of bifid canals; and measurement of anterior loops by two methods. Corticalization of the MC was observed in 59% of hemimandibles. In 23%, MC could be identified despite absence of corticalization. Diameter of MC was between 2.1 and 4 mm for nearly three quarters of the sample. In 80% of the sample trabeculation at the SGF was either decreased or not visible, and such cases showed correlation with absence of MC corticalization. Bifid MC affected 19% of the patients, mostly associated with additional mental foramina. Clinically significant anterior loop (> 2 mm of anterior extension) was observed in 22-28%, depending on the method. Our findings, together with previously reported limitations of conventional exams, draw attention to the unpredictability related to anatomical variations in neurovascularization, showing the contribution of individual assessment through different views of three-dimensional imaging prior to surgical procedures in the mandible.

Location and dimensions of the mental foramen: a radiographic analysis by using cone-beam computed tomography

INTRODUCTION The mental foramen (MF) is an important landmark in dentistry. Knowledge of its position is central to perform block anesthesia of the mental nerve or to avoid nerve damage during surgical procedures in the premolar area of the mandible. The present radiographic study aimed at evaluating the location and dimension of the MF and measuring distances to neighboring structures by using limited cone-beam computed tomography (CBCT). METHODS Sagittal, axial, and coronal CBCT images of 142 patients (26 bilateral and 116 unilateral cases) were retrospectively screened to determine the location of the MF with respect to adjacent teeth and to take linear measurements of the size of the MF and its distances to the upper and lower borders of the mandible. In addition, the course and angulation of the mental canal exiting the MF were assessed. RESULTS The majority of MF (56%) were located apically between the 2 premolars, and another 35.7% of MF were positioned below the second premolar. On average, the MF was localized 5.0 mm from the closest root of the adjacent tooth (range, 0.3-9.8 mm). The mean size of the MF showed a height of 3.0 mm and a length of 3.2 mm; however, individual cases showed large differences in height (1.8-5.1 mm) and in length (1.8-5.5 mm). All mental canals exiting the MF demonstrated an upward course in the coronal plane, with 70.1% of the mental canal presenting an anterior loop (AL) in the axial view. The mean extension of AL in cases with an AL was 2.3 mm. CONCLUSIONS This study is consistent with previous radiographic studies regarding size and location of MF and distances between MF and adjacent anatomic structures. The assessed bilateral cases showed a high intraindividual concordance for certain features when comparing right and left sides.

Modeling 2R regenerator based on High Nonlinear Dispersion Imbalanced Loop Mirror (HN-DILM)

The model of Reshaping and Re-amplification (2R) regenerator based on High Nonlinear Dispersion Imbalanced Loop Mirror (HN-DILM) has been designed to examine its capability to reduce the necessary of fiber loop length and input peak power by deploying High Non linear Fiber (HNLF) compared to Dispersion Shifted Fiber (DSF). The simulation results show by deployed a HNLF as a nonlinear element in Dispersion Imbalanced Loop Mirror (DILM) requires only 400mW peak powers to obtain a peak of transmission compared to DSF which requires a higher peak power at 2000mW to obtain a certain transmissivity. It also shows that HNLF required shorter fiber length to achieve the highest transmission. The 2R regenerator also increases the extinction ratio (ER) of the entire system. © 2010 IEEE.

Faster pairing computations on curves with high-degree twists

Research on efficient pairing implementation has focussed on reducing the loop length and on using high-degree twists. Existence of twists of degree larger than 2 is a very restrictive criterion but luckily constructions for pairing-friendly elliptic curves with such twists exist. In fact, Freeman, Scott and Teske showed in their overview paper that often the best known methods of constructing pairing-friendly elliptic curves over fields of large prime characteristic produce curves that admit twists of degree 3, 4 or 6. A few papers have presented explicit formulas for the doubling and the addition step in Miller’s algorithm, but the optimizations were all done for the Tate pairing with degree-2 twists, so the main usage of the high- degree twists remained incompatible with more efficient formulas. In this paper we present efficient formulas for curves with twists of degree 2, 3, 4 or 6. These formulas are significantly faster than their predecessors. We show how these faster formulas can be applied to Tate and ate pairing variants, thereby speeding up all practical suggestions for efficient pairing implementations over fields of large characteristic.

MRI study of the changes in crystalline lens shape with accommodation and ageing in humans

Magnetic Resonance Imaging was used to study changes in the crystalline lens and ciliary body with accommodation and aging. Monocular images were obtained in 15 young (19-29 years) and 15 older (60-70 years) emmetropes when viewing at far (6m) and at individual near points (14.5 to 20.9 cm) in the younger group. With accommodation, lens thickness increased (mean±95% CI: 0.33±0.06mm) by a similar magnitude to the decrease in anterior chamber depth (0.31±0.07mm) and equatorial diameter (0.32±0.04mm) with a decrease in the radius of curvature of the posterior lens surface (0.58±0.30mm). Anterior lens surface shape could not be determined due to the overlapping region with the iris. Ciliary ring diameter decreased (0.44±0.17mm) with no decrease in circumlental space or forward ciliary body movement. With aging, lens thickness increased (mean±95% CI: 0.97±0.24mm) similar in magnitude to the sum of the decrease in anterior chamber depth (0.45±0.21mm) and increase in anterior segment depth (0.52±0.23mm). Equatorial lens diameter increased (0.28±0.23mm) with no change in the posterior lens surface radius of curvature. Ciliary ring diameter decreased (0.57±0.41mm) with reduced circumlental space (0.43±0.15mm) and no forward ciliary body movement. Accommodative changes support the Helmholtz theory of accommodation including an increase in posterior lens surface curvature. Certain aspects of aging changes mimic accommodation.

Structural diversity and ligand specificity of lectins. The Bangalore effort

Structural studies in this laboratory encompass four of the five major classes of plant lectins, including the one discovered by us. In addition to addressing issues specific to individual lectins, the work provided insights into protein folding, quaternary association and generation of ligand specificity. Legume and beta-prism fold lectins constitute families of proteins in which small alterations in essentially the same tertiary structure lead to large variations in quaternary structure, including that involving an open structure. Strategies for generating ligand specificity include water bridges, variation in loop length, post translational modification and oligomerization. Three of the structural classes investigated have subunits with three-fold symmetry. The symmetry in the structure is reflected in the sequence to different extents in different subclasses. The evolutionary implications of this observation have been explored. The work on lectins has now been extended to those from mycobacteria.

The periodic variations of a white-light flare observed with ULTRACAM

High time resolution observations of a white-light flare on the active star EQ PegB show evidence of intensity variations with a period of ≈10 s. The period drifts to longer values during the decay phase of the flare. If the oscillation is interpreted as an impulsively-excited, standing-acoustic wave in a flare loop, the period implies a loop length of ≈3.4 Mm and ≈6.8 Mm for the case of the fundamental mode and the second harmonic, respectively. However, the small loop lengths imply a very high modulation depth making the acoustic interpretation unlikely. A more realistic interpretation may be that of a fast-MHD wave, with the modulation of the emission being due to the magnetic field. Alternatively, the variations could be due to a series of reconnection events. The periodic signature may then arise as a result of the lateral separation of individual flare loops or current sheets with oscillatory dynamics (i.e., periodic reconnection).

The Decaying Long-period Oscillation of a Stellar Megaflare

We analyze and interpret the oscillatory signal in the decay phase of the U-band light curve of a stellar megaflare observed on 2009 January 16 on the dM4.5e star YZ CMi. The oscillation is well approximated by an exponentially decaying harmonic function. The period of the oscillation is found to be 32 minutes, the decay time about 46 minutes, and the relative amplitude 15%. As this observational signature is typical of the longitudinal oscillations observed in solar flares at extreme ultraviolet and radio wavelengths, associated with standing slow magnetoacoustic waves, we suggest that this megaflare may be of a similar nature. In this scenario, macroscopic variations of the plasma parameters in the oscillations modulate the ejection of non-thermal electrons. The phase speed of the longitudinal (slow magnetoacoustic) waves in the flaring loop or arcade, the tube speed, of about 230 km s-1 would require a loop length of about 200 Mm. Other mechanisms, such as standing kink oscillations, are also considered.

Simulations numériques de la dynamique des protéines : translation de ligands, flexibilité et dynamique des boucles

La flexibilité est une caractéristique intrinsèque des protéines qui doivent, dès le mo- ment de leur synthèse, passer d’un état de chaîne linéaire à un état de structure tridimen- sionnelle repliée et enzymatiquement active. Certaines protéines restent flexibles une fois repliées et subissent des changements de conformation de grande amplitude lors de leur cycle enzymatique. D’autres contiennent des segments si flexibles que leur structure ne peut être résolue par des méthodes expérimentales. Dans cette thèse, nous présentons notre application de méthodes in silico d’analyse de la flexibilité des protéines : • À l’aide des méthodes de dynamique moléculaire dirigée et d’échantillonnage pa- rapluie, nous avons caractérisé les trajectoires de liaison de l’inhibiteur Z-pro- prolinal à la protéine Prolyl oligopeptidase et identifié la trajectoire la plus pro- bable. Nos simulations ont aussi identifié un mode probable de recrutement des ligands utilisant une boucle flexible de 19 acides aminés à l’interface des deux domaines de la protéine. • En utilisant les méthodes de dynamique moléculaire traditionnelle et dirigée, nous avons examiné la stabilité de la protéine SAV1866 dans sa forme fermée insérée dans une membrane lipidique et étudié un des modes d’ouverture possibles par la séparation de ses domaines liant le nucléotide. • Nous avons adapté auproblème de la prédiction de la structure des longues boucles flexibles la méthode d’activation et de relaxation ART-nouveau précédemment uti- lisée dans l’étude du repliement et de l’agrégation de protéines. Appliqué au replie- ment de boucles de 8 à 20 acides aminés, la méthode démontre une dépendance quadratique du temps d’exécution sur la longueur des boucles, rendant possible l’étude de boucles encore plus longues.

Estudos sobre estrutura, ciclo de vida e comportamento de Sardinella brasiliensis (Steindachner, 1879) na área entre 22ºS e 28ºS, Brasil: 4. Crescimento: aspectos quantitativos

Foram estimados os parâmetros de crescimento em comprimento e peso para Sardinella brasiliensisda costa sudeste do Brasil (22ºS-28ºS), evidenciando-se dois padrões de crescimento distintos: um, para os exemplares que ocupam as regiões estuarino-lagunares de Cananeia e Paranaguá (25º-26ºS; III) e outro, para aqueles que ocupam as regiões costeiras da plataforma. Nestas regiões foi identificado um grupo no extremo norte da região (22º- 23ºS; I) com crescimento mais intenso que o verificado para o resto da área (23º-25ºS; II e 26º- 28ºS; IV). Os resultados sugerem que a espécie não é homogênea na região, reforçando hipótese anterior.