University of Colorado Boulder

About: University of Colorado Boulder is a education organization based out in Boulder, Colorado, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 48794 authors who have published 115151 publications receiving 5387328 citations. The organization is also known as: CU Boulder & UCB.

Sequential click reactions for synthesizing and patterning three-dimensional cell microenvironments

Abstract: Click chemistry provides extremely selective and orthogonal reactions that proceed with high efficiency and under a variety of mild conditions, the most common example being the copper(I)-catalysed reaction of azides with alkynes. While the versatility of click reactions has been broadly exploited, a major limitation is the intrinsic toxicity of the synthetic schemes and the inability to translate these approaches into biological applications. This manuscript introduces a robust synthetic strategy where macromolecular precursors react through a copper-free click chemistry, allowing for the direct encapsulation of cells within click hydrogels for the first time. Subsequently, an orthogonal thiol-ene photocoupling chemistry is introduced that enables patterning of biological functionalities within the gel in real time and with micrometre-scale resolution. This material system enables us to tailor independently the biophysical and biochemical properties of the cell culture microenvironments in situ. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gels with ideal structures that can be photopatterned, and all in the presence of cells.

Improved Semantic Representations From Tree-Structured Long Short-Term Memory Networks

Abstract: Because of their superior ability to preserve sequence information over time, Long Short-Term Memory (LSTM) networks, a type of recurrent neural network with a more complex computational unit, have obtained strong results on a variety of sequence modeling tasks. The only underlying LSTM structure that has been explored so far is a linear chain. However, natural language exhibits syntactic properties that would naturally combine words to phrases. We introduce the Tree-LSTM, a generalization of LSTMs to tree-structured network topologies. Tree-LSTMs outperform all existing systems and strong LSTM baselines on two tasks: predicting the semantic relatedness of two sentences (SemEval 2014, Task 1) and sentiment classification (Stanford Sentiment Treebank).

Social Exchange Theory: A Critical Review with Theoretical Remedies

Abstract: Social exchange theory is one of the most prominent conceptual perspectives in management, as well as related fields like sociology and social psychology. An important criticism of social exchange theory; however, is that it lacks sufficient theoretical precision, and thus has limited utility. Scholars who apply social exchange theory are able to explain many social phenomena in post hoc manner but are severely limited in their ability to make useful a priori predictions regarding workplace behavior. In this review, we discuss social exchange theory as it exists today and identify four critical issues within the social exchange paradigm that warrant additional consideration. The four concerns, around which we center this review, include the following: (1) overlapping constructs that need to be more clearly distinguished; (2) insufficient appreciation to the positive or negative hedonic value of these various constructs; (3) an assumption of bipolarity, which treats negative constructs (e.g., abuse) as the absence of positive constructs (e.g., support); and, following from the prior three issues, (4) theoretically imprecise behavioral predictions. Given that these problems are inherent in the current unidimensional framework for social exchange theory, we suggest an additional dimension–activity. We explain how conceptualizing social exchange within a two-dimensional space, while giving equal consideration to both hedonic value and activity, creates new opportunities for future research.

Evolutionary and Ecological Aspects of Photosynthetic Pathway Variation

Abstract: C4 and CAM photosynthesis are evolutionarily derived from C3 photosynthesis. The morphological and biochemical modifications necessary to achieve either C4 or CAM photosynthesis are thought to have independently arisen numerous times within different higher plant taxa. It is thought that C4 photosynthesis evolved in response to the low atmospheric CO2 concentrations that arose sometime after the end of the Cretaceous. Low CO2 concentrations result in significant increases in photorespiration of C3 plants, reducing productivity; both C3-C4 intermediate and C4 plants exhibit reduced photorespiration rates. In contrast, it may be argued that CAM arose either in response to selection of increased water-use efficiency or for increased carbon gain. Globally, all three pathways are widely distributed today, with a tendency toward ecological adaptation of C4 plants into warm, monsoonal climates and CAM plants into water-limited habitats. In an anthropogenically altered CQ2 environment, C4 plants may lose their competitive advantage over C3 plants. 411