The biology of vision of Drosophila.

Phototransduction systems in vertebrates and invertebrates share a great deal of similarity in overall strategy but differ significantly in the underlying molecular machinery. Both are rhodopsin-based G protein-coupled signaling cascades displaying exquisite sensitivity and broad dynamic range. However, light activation of vertebrate photoreceptors leads to activation of a cGMP-phosphodiesterase effector and the generation of a hyperpolarizing response. In contrast, activation of invertebrate photoreceptors, like Drosophila, leads to stimulation of phospholipase C and the generation of a depolarizing receptor potential. The comparative study of these two systems of phototransduction offers the opportunity to understand how similar biological problems may be solved by different molecular mechanisms of signal transduction. The study of this process in Drosophila, a system ideally suited to genetic and molecular manipulation, allows us to dissect the function and regulation of such a complex signaling cascade in its normal cellular environment. In this manuscript I review some of our recent findings and the strategies used to dissect this process.

Homeologous recombination and mismatch repair during transformation in Streptococcus pneumoniae: saturation of the Hex mismatch repair system.

The ability of the Hex generalized mismatch repair system to prevent recombination between partially divergent (also called homeologous) sequences during transformation in Streptococcus pneumoniae was investigated. By using as donor in transformation cloned fragments 1.7-17.5% divergent in DNA sequence from the recipient, it was observed that the Hex system prevents chromosomal integration of the least and the most divergent fragments but frequently fails to do so for other fragments. In the latter case, the Hex system becomes saturated (inhibited) due to an excess of mismatches: it is unable to repair a single mismatch located elsewhere on the chromosome. Further investigation with chromosomal donor DNA, carrying only one genetically marked divergent region, revealed that a single divergent fragment can lead to saturation of the Hex system. Increase in cellular concentration of either HexA, the MutS homologue that binds mismatches, or HexB, the MutL homologue for which the essential role in repair as yet remains obscure, was shown to restore repair ability in previously saturating conditions. Investigation of heterospecific transformation by chromosomal DNA from two related streptococcal species, Streptococcus oralis and Streptococcus mitis, also revealed complete saturation of the Hex system. Therefore the Hex system is not a barrier to interspecies recombination in S. pneumoniae. These results are discussed in light of those described for the Mut system of Escherichia coli.

A chimeric light-regulated amino acid transport system allows the isolation of blue light regulator (blr) mutants of Neurospora crassa.

We have developed a system for the isolation of Neurospora crassa mutants that shows altered responses to blue light. To this end we have used the light-regulated promoter of the albino-3 gene fused to the neutral amino acid permease gene mtr. The product of the mtr gene is required for the uptake of neutral aliphatic and aromatic amino acids, as well as toxic analogs such as p-flurophenylalanine or 4-methyltryptophan. mtr trp-2-carrying cells were transformed with the al-3 promoter-mtr wild-type gene (al-3p-mtr+) to obtain a strain with a light-regulated tryptophan uptake. This strain is sensitive to p-fluorophenylalanine when grown under illumination and resistant when grown in the dark. UV mutagenesis of the al-3p-mtr(+)-carrying strain allowed us to isolate two mutant strains, BLR-1 and BLR-2 (blue light regulator), that are light-resistant to p-fluorophenylalanine and have lost the ability to grow on tryptophan. These two strains have a pale-orange phenotype and show down-regulation of all the photoregulated genes tested (al-3, al-1, con-8, and con-10). Mutations in the BLR strains are not allelic with white collar 1 or white collar 2, regulatory genes that are also involved in the response to blue light.

Electrically Tunable Selective Reflection of Light from Ultraviolet to Visible and Infrared by Heliconical Cholesterics

Acknowledgements This work was supported by NSF DMR-1410378 and DMR-1121288. We thank V. Borshch for helping with preparation of illustrations, to Y. K. Kim for the help in experiments, V. A. Belyakov and S. V. Shiyanovskii for useful discussions.

Effects of Institutional Factors on the Retention of Graduate Students of Color in Schools of Library and Information Science

The intent of the study was to understand the changes that have occurred over the last 25 years in library programs as far as enrollment and diversity of students, number and ethnicity of the faculty, program income and expenses, cost of attendance, and scholarship and fellowship aid, in an effort to better understand library programs granting the MLIS degree. The study also endeavored to identify institutional factors associated with the retention and productivity rates of White students and students of color in schools of library and information science. During the period studied, the proportional representation of White students decreased. For students of color, proportional representation was stable during the same time period. Results revealed a medium effect size of time with productivity rates for both groups declining over time. Retention rate differed significantly by time, with a small effect size with retention rate that initially increased over time, but is now decreasing. The final analyses were meta-regressions to determine if retention and productivity rates can be predicted by cost of attendance, scholarship and fellow aid, and program size. Results indicated that for students of color, program size in 2000 was significantly predictive of retention, cost of attendance was predictive in 2002, and scholarship and fellowship aid was predictive of retention in 2004. No variables were significantly predictive for retention of White students. The last analysis was to determine if productivity rate can be predicted by cost of attendance, scholarship and fellow aid, and program size. Results indicate that for White students in 2002, the cost of attendance was predictive of productivity rating. In 2003, scholarship and fellowship aid was predictive of productivity rate and in 2004, scholarship and fellowship aid was predictive of productivity rating. For students of color, results indicate that only scholarship and fellowship aid in 2005 was predictive of productivity rate. No other variables in any of the years studied showed any significant prediction of productivity rating for students of color.

Disponibilidade de níquel no sistema solo-planta: efeito de doses e saturações por bases

Por se tratar de um elemento essencial às plantas e um metal pesado ao mesmo tempo, o níquel requer atenção quanto aos aspectos da fisiologia de plantas e ambiental. Além disso, existe um intervalo estreito entre as exigências nutricionais e os teores tóxicos às plantas. Neste contexto, objetivou-se avaliar o efeito do Ni no sistema solo-planta, com foco no ciclo do N e a disponibilidade do elemento no solo, por meio de experimento em condições controladas, utilizando vasos distribuídos inteiramente ao acaso, utilizando-se esquema fatorial 2 x 5, com sete repetições cada tratamento. O primeiro fator foi constituído de duas saturações por base (50 e 70%) e o segundo de cinco doses de Ni (0; 0,1; 0,5; 1,0 e 10,0 mg dm-3 de solo). Os vasos foram preenchidos com 8 dm3 de terra e cultivados com soja [Glycine max (L.) Merrill] sucedida por girassol (Helianthus annuus L.). Os parâmetros qualitativos e quantitativos: altura de plantas (AP), diâmetro do caule (DC), número de nós (NN), estádio fenológico (EF), índice SPAD e, diâmetro do capítulo (DCap) (para girassol) foram avaliadas aos 30 e 60 dias após a emergência (d.a.e.) de cada cultivo. Plantas inteiras de soja, amostradas em quatro vasos de cada tratamento, foram coletadas no estádio R1. Na mesma ocasião foram coletadas amostras de solo da rizosfera. Em seguida, as plantas coletadas foram divididas em: folhas; raízes (nódulos na soja) e parte aérea. Foram determinados nas folhas utilizadas para diagnose em soja e girassol: os teores de macro e micronutrientes, as atividades da redutase do nitrato e da urease e as concentrações dos ácidos orgânicos: oxálico, malônico, succínico, málico, tartárico, fumárico, oxaloacético, cítrico e lático. Os mesmos ácidos orgânicos foram determinados em raízes secundárias de girassol e nódulos de soja. Foram realizadas avaliações ultraestruturais por meio de microscopia eletrônica de transmissão (MET) em raízes de girassol, e estruturais e de tonalidade em nódulos de soja, por meio de microscopia de luz. No solo, foram determinadas: atividade urease, desidrogenase, Ni total e fitodisponível pelos métodos: Mehlich-1, Mehlich-3 e DTPA. No período de maturidade fisiológica de cada cultura foi realizada a colheita das plantas dos vasos restantes para determinação de produção de grãos, teores de Ni na planta inteira e Ni e N nos grãos. Ao final dos dois experimentos foi realizada nova coleta de solo para extração sequencial de Ni. O índice SPAD em soja aos 60 d.a.e., a produção de massa seca da parte aérea da soja e da raiz de girassol foram influenciados pela saturação por bases, doses de níquel e pela a interação destes. Foram influenciados pelas saturações por base e doses de níquel (fatores isolados): para soja: AP aos 60 d.a.e., NN aos 30 e 60 d.a.e., SPAD aos 30 d.a.e.; para girassol: AP e NN aos 30 e 60 d.a.e., DC e SPAD aos 30 d.a.e. As demais variáveis avaliadas aos 30 e 60 d.a.e. foram influenciadas apenas pela saturação por bases, ou doses de Ni separadamente. As plantas de soja e girassol apresentaram maiores teores de Ni nos diferentes tecidos avaliados (exceto grãos) quando cultivadas sob V50%. A produção de grãos de soja e girassol não foi influenciada pelos tratamentos, porém o teor de N dos grãos de soja influenciado pelas doses de Ni na V70%. A atividade da enzima urease nas folhas de soja e girassol foi responsiva positivamente ao aumento das doses de Ni. Quatro dos ácidos orgânicos avaliados e o teor de N nas folhas e nos grãos foram maiores nas plantas cultivadas sob V70% com a dose de 0,5 mg dm-3 de Ni. As doses de Ni bem com as saturações por bases influenciaram diretamente o balanço de nutrientes das plantas. Os extratores Mehlich-1, Mehlich-3 e DTPA apresentaram elevado coefienciente de correlação entre a fração de Ni disponível no solo e a concentração do elemento nas plantas de soja e girassol, sendo o extrator DTPA o que apresentou maior coeficiente de correlação. O Ni apresentou distribuição variável entre as diferentes frações do solo em função dos tratamentos. Os solos dos tratamentos com saturação por bases de 70% apresentaram maior concentração de Ni ligado a carbonato, comparado aos tratamentos sob saturação por bases de 50%. A distribuição do Ni entre as frações do solo seguiu a seguinte orgem: ligado a carbonato < trocável < ligado a óxidos < matéria orgânica < residual. A saturação por bases exerceu efeito diferenciado para a atividade da urease no solo em função da cultura avaliada. Por sua vez, o Ni exerceu efeito diferenciado sobre a atividade de desidrogenase em função da cultura estudada

BigLaw Identity Capital: Pink and Blue, Black and White

This Article advances a new capital framework for understanding the bargain between large law firms and their lawyers, depicting BigLaw relationships not as basic labor-salary exchanges but rather as complex transactions in which large law firms and their lawyers exchange labor and various forms of capital — social, cultural, and identity. First, it builds on the work of Pierre Bourdieu regarding economic, cultural, symbolic, and social capital by examining the concepts of positive and negative capital, exploring the meaning of capital ownership by entities, and developing the notion of identity capital — the value individuals and institutions derive from their identities. Then, the Article advances a capital theory of BigLaw, in which large law firms and their lawyers engage in complex transactions trading labor, social, cultural, and identity capital for economic, social, cultural, and identity capital. Capital analysis sheds new light on the well-documented and troubling underrepresentation of diverse lawyers at BigLaw. It shows that the underrepresentation of women and minority lawyers is not solely the result of exogenous forces outside the control of large law firms such as implicit bias, but rather the outcome of the very exchanges in which BigLaw and its lawyers engage. Specifically, large law firms take into account the capital endowments of their lawyers in making hiring, retention and promotion decisions, and derive value from their lawyers’ capital, for example, by trading on the identity of women and minority lawyers in marketing themselves as being diverse and inclusive to clients and potential recruits. Yet, while BigLaw trades for the identity capital of women and minority lawyers, it fails to offer them opportunities in return to acquire the social and cultural capital necessary for attaining positions of power, resulting in underrepresentation. Moreover, these labor-capital exchanges are often implicit and made by uninformed participants, and therefore unjust. Exactly because the capital framework describes the underrepresentation of diverse lawyers at BigLaw as an endogenous outcome within the control of BigLaw and its lawyers, however, it is a cautiously optimistic model that offers hope for greater representation of diverse lawyers in positions of power and influence. The Article suggests policies and procedures BigLaw can and should adopt to improve the quality of the exchanges it offers to women and minority attorneys and to reduce the underrepresentation of diverse lawyers within its ranks. Employing the concepts of capital transparency, capital boundary, and capital infrastructure, it demonstrates how BigLaw can (1) explicitly recognize the roles social, cultural, and identity capital play in its hiring, retention and promotion apparatuses and (2) revise its policies and procedures to ensure that all of its lawyers have equal opportunities to develop the requisite capital and compete on equal and fair terms for positions of power and influence.

Restrictive and Expansive Views of Equality: A Grounded Theory Study that Explores the Influence of Racial Consciousness on the Behaviors of White Faculty in the Classroom

Attempts to address the ever increasing achievement gap among students have failed to explain how and why educational traditions and teaching practices perpetuate the devaluing of some and the overvaluing of others. This predicament, which plagues our educational system, has been of increased concern, given the growing racial diversity among college students and the saturation of White faculty in the academy. White faculty make up the majority, 79%, of all faculty in the academy. White faculty, whether consciously or unconsciously, are less likely to interrogate how race and racism both privilege them within the academy and influence their faculty behaviors. The result of this cyclical, highly cemented process suggests that there is a relationship between racial consciousness and White faculty members' ability to employ behaviors in their classroom that promote equitable educational outcomes for racially minoritized students. An investigation of the literature revealed that racial consciousness and the behaviors of White faculty in the classroom appeared to be inextricably linked. A conceptual framework, Racial Consciousness and Its Influence on the Behaviors of White Faculty in the Classroom was developed by the author and tested in this study. Constructivist grounded theory was used to explore the role White faculty believe they play in the dismantling of the white supremacy embedded in their classrooms through their faculty behaviors. A substantive theory subsequently emerged. Findings indicate that White faculty with a higher level of racial consciousness employ behaviors in their classroom reflective of a more expansive view of equality in their pursuit of social justice, which they consider synonymous with excellence in teaching. This research bears great significance to higher education research and practice, as it is the first of its kind to utilize critical legal scholar Kimberlé Crenshaw's (1988) restrictive and expansive views of equality framework to empirically measure and describe excellence in college teaching. Implications for faculty preparation and continued education are also discussed.

Analysis of the colorimetric properties of goniochromatic colors using the MacAdam limits under different light sources

Technological innovation in all areas has led to the appearance in recent years of new metallic and pearlescent materials, yet no exhaustive studies have been conducted to assess their colorimetric capabilities. The chromatic variability of these special-effect pigments may largely be due to the three-dimensional effect of their curved shapes and orientations when they are directionally or diffusely illuminated. Our study examines goniochromatic colors using the optimal colors (MacAdam limits) associated with normal colors (photometric scale of relative spectral reflectance from 0 to 1) under certain conventional illuminants and other light sources. From a database of 91 metallic and interference samples and using a multi-gonio-spectrophotometer, we analyzed samples with lightness values of more than 100 and others with lightness values of less than 100, but with higher chromaticities than optimal colors, which places them beyond the MacAdam limits. Our study thus demonstrates the existence of chromatic perceptions beyond the normal solid color associated with these materials and independent of the light source. The challenge for future research, therefore, is to replicate and render these color appearances in current and future color reproduction technologies for computer graphics.

Portable 3D laser-camera calibration system with color fusion for SLAM

Nowadays, the use of RGB-D sensors have focused a lot of research in computer vision and robotics. These kinds of sensors, like Kinect, allow to obtain 3D data together with color information. However, their working range is limited to less than 10 meters, making them useless in some robotics applications, like outdoor mapping. In these environments, 3D lasers, working in ranges of 20-80 meters, are better. But 3D lasers do not usually provide color information. A simple 2D camera can be used to provide color information to the point cloud, but a calibration process between camera and laser must be done. In this paper we present a portable calibration system to calibrate any traditional camera with a 3D laser in order to assign color information to the 3D points obtained. Thus, we can use laser precision and simultaneously make use of color information. Unlike other techniques that make use of a three-dimensional body of known dimensions in the calibration process, this system is highly portable because it makes use of small catadioptrics that can be placed in a simple manner in the environment. We use our calibration system in a 3D mapping system, including Simultaneous Location and Mapping (SLAM), in order to get a 3D colored map which can be used in different tasks. We show that an additional problem arises: 2D cameras information is different when lighting conditions change. So when we merge 3D point clouds from two different views, several points in a given neighborhood could have different color information. A new method for color fusion is presented, obtaining correct colored maps. The system will be tested by applying it to 3D reconstruction.

Portable 3D laser-camera calibration system with color fusion for SLAM

Paper submitted to the 43rd International Symposium on Robotics (ISR2012), Taipei, Taiwan, Aug. 29-31, 2012.

The current challenges of Color Physics and Chemistry

Day of Chemistry, Invited conference, San Alberto Magno 2014

Spectrally tunable light source based on light-emitting diodes for custom lighting solutions

This study describes a novel spectral LED-based tunable light source used for customized lighting solutions, especially for the reconstruction of CIE (Commission Internationale de l’Éclairage) standard illuminants. The light source comprises 31 spectral bands ranging from 400 to 700 nm, an integrating cube and a control board with a 16-bit resolution. A minimization algorithm to calculate the weighting values for each channel was applied to reproduce illuminants with precision. The differences in spectral fitting and colorimetric parameters showed that the reconstructed spectra were comparable to the standard, especially for the D65, D50, A and E illuminants. Accurate results were also obtained for illuminants with narrow peaks such as fluorescents (F2 and F11) and a high-pressure sodium lamp (HP1). In conclusion, the developed spectral LED-based light source and the minimization algorithm are able to reproduce any CIE standard illuminants with a high spectral and colorimetric accuracy able to advance available custom lighting systems useful in the industry and other fields such as museum lighting.

Railway map of routes to the White Mountains, New Hampshire 1859 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Railway map of routes to the White Mountains, by Harvey Boardman. It was published in 1859 by J.H. Bufford's Lith. Scale not given. Covers New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, and portions of Maine, New York, and the province of Quebec, Canada. The image inside the map neatline is georeferenced to the surface of the earth and fit to the USA Contiguous Albers Equal Area Conic projection (Meters). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows features such as roads, railroads, railroad stations, drainage, selected cities, towns, villages, and points of interest (hotels, houses, etc.), state boundaries, and more. Relief shown by hachures. Includes text on routes in margins. This layer is part of a selection of digitally scanned and georeferenced historic maps of New England from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

The white gene and locomotor recovery from anoxia in Drosophila melanogaster

Locomotor recovery from anoxia is complicated and little is known about the molecular and cellular mechanisms regulating anoxic recovery in Drosophila. For this thesis I established a protocol for large-scale analysis of locomotor activity in adult flies with exposure to a transient anoxia. Using this protocol I observed that wild-type Canton-S flies recovered faster and more consistently from anoxia than the white-eyed mutant w1118, which carries a null allele of w1118 in an isogenic genetic background. Both Canton-S and w1118 are commonly used controls in the Drosophila community. Genetic analysis including serial backcrossing, RNAi knockdown, w+ duplication to Y chromosome as well as gene mutation revealed a strong association between the white gene and the timing of locomotor recovery. I also found that the locomotor recovery phenotype is independent of white-associated eye pigmentation, that heterozygous w+ allele was haplo-insufficient to induce fast and consistent locomotor recovery from anoxia in female flies, and that mini-white is insufficient to promote fast and consistent locomotor recovery. Moreover, locomotor recovery was delayed in flies with RNAi knockdown of white in subsets of serotonin neurons in the central nervous system. I further demonstrated that mutations of phosphodiesterase genes (PDE) displayed wild-type-like fast and consistent locomotor recovery, and that locomotor recovery was light-sensitive in the night in w1118. The delayed locomotor recovery and the light sensitivity were eliminated in PDE mutants that were dual-specific or cyclic guanosine monophosphate (cGMP)-specific. Up-regulation of cGMP using multiple approaches including PDE mutation, sildenafil feeding or specific expression of an atypical soluble guanylyl cyclase (Gyc88E) was sufficient to suppress w-RNAi induced delay of locomotor recovery. Taken together, these data strongly support the hypothesis that White transports cGMP and promotes fast and consistent locomotor recovery from anoxia.