A call for scientists to halt the spoiling of the night sky with artificial light and satellites

Unfettered access to dark night skies is rapidly diminishing, due to light pollution and satellite mega-constellations tracks. Scientists should wake up and do more to stand up to Big Light and Big Space and preserve this natural resource.Comment: 5 pages; not edited version of the manuscript published in Nature Astronom

Towards the development of a hybrid-integrated chip interferometer for online surface profile measurements

Non-destructive testing and online measurement of surface features are pressing demands in manufacturing. Thus optical techniques are gaining importance for characterization of complex engineering surfaces. Harnessing integrated optics for miniaturization of interferometry systems onto a silicon wafer and incorporating a compact optical probe would enable the development of a handheld sensor for embedded metrology applications. In this work, we present the progress in the development of a hybrid photonics based metrology sensor device for online surface profile measurements. The measurement principle along with test and measurement results of individual components has been presented. For non-contact measurement, a spectrally encoded lateral scanning probe based on the laser scanning microscopy has been developed to provide fast measurement with lateral resolution limited to the diffraction limit. The probe demonstrates a lateral resolution of ∼3.6 μm while high axial resolution (sub-nanometre) is inherently achieved by interferometry. Further the performance of the hybrid tuneable laser and the scanning probe was evaluated by measuring a standard step height sample of 100 nm

The Iteratively Regularized Gau{\ss}-Newton Method with Convex Constraints and Applications in 4Pi-Microscopy

This paper is concerned with the numerical solution of nonlinear ill-posed operator equations involving convex constraints. We study a Newton-type method which consists in applying linear Tikhonov regularization with convex constraints to the Newton equations in each iteration step. Convergence of this iterative regularization method is analyzed if both the operator and the right hand side are given with errors and all error levels tend to zero. Our study has been motivated by the joint estimation of object and phase in 4Pi microscopy, which leads to a semi-blind deconvolution problem with nonnegativity constraints. The performance of the proposed algorithm is illustrated both for simulated and for three-dimensional experimental data

Transport of water into the lower mantle: Role of stishovite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95319/1/jgrb13563.pd

Forms of Science Capital Mobilized in Adolescents’ Engineering Projects

The purpose of this multiple case study was to identify the forms of science capital that six groups of adolescents mobilized toward the realization of their self-selected engineering projects during after-school meetings. Research participants were high school students who self-identified as Hispanic, Latina, or Latino; who had received English as a Second Language (ESL) services; and whose parents or guardians had immigrated to the United States and held working class jobs. The research team used categories from Bourdieusian theories of capital to identify the forms of science capital mobilized by the participants. Data sources included transcripts from monthly interviews and from bi-monthly group meetings during which the group members worked on their engineering projects. Data analysis indicated that the groups activated science capital in the following categories: embodied capital in the form of formal scientific knowledge, literacy practices, and experiences with solving everyday problems; social capital in the form of connections with authorities, experts, and peers; objectified capital in the form of information and communication technologies (ICTs) and measuring tools; and institutional capital in the form of awards and titles. The participants co-mobilized multiple forms of science capital to advance their engineering projects, and some instances of co-mobilization enabled the future activation of subsequent forms of science capital. Engineering, as a vehicle for learning science, provided the youth with opportunities to draw from diverse community resources and from multilingual literacy practices, recasting these resources and skills as forms of science capital, which were mobilized toward the attainment of other high-status forms of science capital

Live cell fluorescence microscopy to study microbial pathogenesis

Advances in microscopy and fluorescent probes provide new insight into the nanometer-scale biochemistry governing the interactions between eukaryotic cells and pathogens. When combined with mathematical modelling, these new technologies hold the promise of qualitative, quantitative and predictive descriptions of these pathways. Using the light microscope to study the spatial and temporal relationships between pathogens, host cells and their respective biochemical machinery requires an appreciation for how fluorescent probes and imaging devices function. This review summarizes how live cell fluorescence microscopy with common instruments can provide quantitative insight into the cellular and molecular functions of hosts and pathogens.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72689/1/j.1462-5822.2009.01283.x.pd

Assembly of high nuclearity clusters from a family of tripodal tris-carboxylate ligands

A family of four tris-carboxylic acid ligands 1,3,5-tris(4′-carboxybiphenyl-2-yl)benzene (H3L1), 1,3,5-tris-2-carboxyphenylbenzene (H3L2), 1,3,5-tris(4″-carboxy-para-terphenyl-2-yl)benzene (H3L3) and 1,3,5-tris(3′-carboxybiphenyl-2-yl)benzene (H3L4) have been synthesised and reacted with first row transition metal cations to give nine complexes which have been structurally characterised by X-ray crystallography. The ligands share a common design motif having three arms connected to a benzene core via three ortho-disubstituted phenyl linkers. The ligands vary in length and direction of the carboxylic acid functionalised arms and are all able to adopt tripodal conformations in which the three arms are directed facially. The structures of [Zn8(μ4-O)(L1)4(HCO2)2(H2O)0.33(DMF)2] (1a-Zn), [Co14(L2)6((μ3-OH)8(HCO2)2(DMF)4(H2O)6] (2-Co), [Ni14(L2)6(μ3-OH)8(HCO2)2(DMF)4(H2O)6] (2-Ni), [Zn8(μ4-O)(L3)4(DMF)(H2O)4(NO3)2] (3-Zn), [Ni5(μ-OH)4(L2)2(H2O)6(DMF)4] (5-Ni), [Co8(μ4-O)4(L4)4(DMF)3(H2O)] (6-Co) and Fe3(μ3-O)(L4)2(H2O)(DMF)2)] (7-Fe) contain polynuclear clusters surrounded by ligands (L1–4)3− in tripodal conformations. The structure of [Zn2(HL1)2(DMF)4] (1b-Zn) shows it to be a binuclear complex in which the two ligands (HL2)2− are partially deprotonated whilst {[Zn3(L2)2(DMF)(H2O)(C5H5N)]·6(DMF)}n (4-Zn) is a 2D coordination network containing {Zn2(RCO2)4(solv)2} paddlewheel units. The conformations of the ligand arms in the complexes have been analysed, confirming that the shared ortho-disubstituted phenyl ring motif is a powerful and versatile tool for designing ligands able to form high-nuclearity coordination clusters when reacted with transition metal cations

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Inhibitory control and the speech patterns of second language users

Inhibitory control (IC), an ability to suppress irrelevant and/or conflicting information, has been found to underlie performance on a variety of cognitive tasks, including bilingual language processing. This study examines the relationship between inhibitory control and the speech patterns of second language (L2) users from the perspective of individual differences. While the majority of studies have supported the role of IC in bilingual language processing using single word production paradigms, this work looks at inhibitory processes in the context of extended speech, with a particular emphasis on disfluencies. We hypothesised that the speech of individuals with poorer IC would be characterised by reduced fluency. A series of regression analyses, in which we controlled for age and L2 proficiency, revealed that IC (in terms of accuracy on the Stroop task) could reliably predict the occurrence of reformulations and the frequency and duration of silent pauses in L2 speech. No statistically significant relationship was found between IC and other L2 spoken output measures, such as repetitions, filled pauses, and performance errors. Conclusions focus on IC as one out of a number of cognitive functions in the service of spoken language production. A more qualitative approach towards the question of whether L2 speakers rely on IC is advocated

Sequence-Dependent Fluorescence of Cyanine Dyes on Microarrays

Cy3 and Cy5 are among the most commonly used oligonucleotide labeling molecules. Studies of nucleic acid structure and dynamics use these dyes, and they are ubiquitous in microarray experiments. They are sensitive to their environment and have higher quantum yield when bound to DNA. The fluorescent intensity of terminal cyanine dyes is also known to be significantly dependent on the base sequence of the oligonucleotide. We have developed a very precise and high-throughput method to evaluate the sequence dependence of oligonucleotide labeling dyes using microarrays and have applied the method to Cy3 and Cy5. We used light-directed in-situ synthesis of terminally-labeled microarrays to determine the fluorescence intensity of each dye on all 1024 possible 5′-labeled 5-mers. Their intensity is sensitive to all five bases. Their fluorescence is higher with 5′ guanines, and adenines in subsequent positions. Cytosine suppresses fluorescence. Intensity falls by half over the range of all 5-mers for Cy3, and two-thirds for Cy5. Labeling with 5′-biotin-streptavidin-Cy3/-Cy5 gives a completely different sequence dependence and greatly reduces fluorescence compared with direct terminal labeling