Massachusetts Institute of Technology

About: Massachusetts Institute of Technology is a education organization based out in Cambridge, Massachusetts, United States. It is known for research contribution in the topics: Population & Laser. The organization has 116795 authors who have published 268000 publications receiving 18272025 citations. The organization is also known as: MIT & M.I.T..

Near-infrared fluorescent type II quantum dots for sentinel lymph node mapping

Abstract: The use of near-infrared or infrared photons is a promising approach for biomedical imaging in living tissue. This technology often requires exogenous contrast agents with combinations of hydrodynamic diameter, absorption, quantum yield and stability that are not possible with conventional organic fluorophores. Here we show that the fluorescence emission of type II quantum dots can be tuned into the near infrared while preserving absorption cross-section, and that a polydentate phosphine coating renders them soluble, disperse and stable in serum. We then demonstrate that these quantum dots allow a major cancer surgery, sentinel lymph node mapping, to be performed in large animals under complete image guidance. Injection of only 400 pmol of near-infrared quantum dots permits sentinel lymph nodes 1 cm deep to be imaged easily in real time using excitation fluence rates of only 5 mW/cm(2). Taken together, the chemical, optical and in vivo data presented in this study demonstrate the potential of near-infrared quantum dots for biomedical imaging.

Bibliographic coupling between scientific papers

Abstract: This report describes the results of automatic processing of a large number of scientific papers according to a rigorously defined criterion of coupling. The population of papers under study was ordered into groups that satisfy the stated criterion of interrelation. An examination of the papers that constitute the groups shows a high degree of logical correlation.

Sketchpad: a man-machine graphical communication system

Abstract: The Sketchpad system makes it possible for a man and a computer to converse rapidly through the medium of line drawings. Heretofore, most interaction between man and computers has been slowed down by the need to reduce all communication to written statements that can be typed; in the past, we have been writing letters to rather than conferring with our computers. For many types of communication, such as describing the shape of a mechanical part or the connections of an electrical circuit, typed statements can prove cumbersome. The Sketchpad system, by eliminating typed statements (except for legends) in favor of line drawings, opens up a new area of man-machine communication.

Managerial Incentive Problems: A Dynamic Perspective

Abstract: The paper studies how a person's concern for a future career may influence his or her incentives to put in effort or make decisions on the job. In the model, the person's productive abilities are revealed over time through observations of performance. There are no explicit output-contingent contracts, but since the wage in each period is based on expected output and expected output depends on assessed ability, an "implicit contract" links today's performance to future wages. An incentive problem arises from the person's ability and desire to influence the learning process, and therefore the wage process, by taking unobserved actions that affect today's performance. The fundamental incongruity in preferences is between the individual's concern for human capital returns and the firm's concern for financial returns. The two need be only weakly related. It is shown that career motives can be beneficial as well as detrimental, depending on how well the two kinds of capital returns are aligned. It is well understood by now that informational externalities may place special demands on the organization of economic exchange. Simple price-mediated markets will frequently fail in the presence of asymmetric information. In that case more elaborate contractual arrangements have to be used as substitutes for the price system. Lately, considerable effort has been devoted to the analysis of contracting under incomplete information with the objective to understand the range of economic institutions that emerge in response to the failure of the price system. The analysis of moral hazard has played a prominent role in this development.' Moral hazard problems arise when, for some reason or another, transacting parties cannot contract contingent on the delivery of the good. For instance, in buying labour services it may be that the amount of labour supplied is not directly observable, precluding a simple exchange of wage for labour. As a partial remedy to this problem, an imperfect, mutually observed signal about the supply of labour can be used as a proxy in the contract. Frequently, output is taken as such a proxy. The drawback is that output is often influenced by other factors than labour input, which induce undesirable risk into the contract. One is therefore faced with a tradeoff between allocating risk associated with incomplete observability and providing incentives for a proper supply of labour. Gaining insight into this tradeoff is important not only for understanding contracting in the small (e.g. managerial incentive schemes), but also because it is closely related to the fundamental tension between equity and efficiency in the society as a whole. While our understanding of moral hazard has advanced a lot in past years, it is clear that much work remains. An important question that has received little attention until

Heteronuclear decoupling in rotating solids

Abstract: A simple two pulse phase modulation (TPPM) scheme greatly reduces the residual linewidths arising from insufficient proton decoupling power in double resonance magic angle spinning (MAS) experiments. Optimization of pulse lengths and phases in the sequence produces substantial improvements in both the resolution and sensitivity of dilute spins (e.g., 13C) over a broad range of spinning speeds at high magnetic field. The theoretical complications introduced by large homo‐ and heteronuclear interactions among the spins, as well as the amplitude modulation imposed by MAS, are explored analytically and numerically. To our knowledge, this method is the first phase‐switched sequence to exhibit improvement over continuous‐wave (cw) decoupling in a strongly coupled homogeneous spin system undergoing sample spinning.