Time filter

Source Type

Saint Andrews, United Kingdom

The University of St Andrews is a public research university in St Andrews, Fife, Scotland. It is the oldest of the four ancient universities of Scotland, and the third oldest university in the English-speaking world . It was founded between 1410 and 1413 when the Avignon Antipope Benedict XIII issued a Papal Bull to a small founding group of Augustinian clergy.St Andrews is made up from a variety of institutions, including three constituent colleges and 18 academic Schools organized into four Faculties. The university occupies historic and modern buildings located throughout the town. The academic year is divided into two terms, Martinmas and Candlemas. In term time, over a third of the town's population is either a staff member or student of the university. The student body is notably diverse: over 30% of its intake come from well over 100 countries, 15% from North America. The University's sport teams compete in BUCS competitions, and the student body is known for preserving ancient traditions such as Raisin Weekend, May Dip, and the wear of distinctive academic dress.National league tables currently rank St Andrews as the third best university in the United Kingdom. The Schools of Physics and Astronomy, International Relations, Computer Science and Mathematics are ranked first in the United Kingdom by The Guardian. International league tables rank St Andrews less highly, due in part to its small size, though The Times Higher Education World Universities Ranking names St Andrews among the world’s Top 20 Arts and Humanities universities. St Andrews has the highest student satisfaction amongst all multi-faculty universities in the United Kingdom.St Andrews has many notable alumni and affiliated faculty, including eminent mathematicians, scientists, theologians, philosophers, and politicians. Recent alumni include the former First Minister of Scotland Alex Salmond; Secretary of State for Defence Michael Fallon; United States Ambassador to Hungary Colleen Bell; Olympic gold medalist Chris Hoy; actor Crispin Bonham-Carter; and royals Prince William, Duke of Cambridge, and Catherine, Duchess of Cambridge. It boasts five Nobel Laureates: two in Chemistry and one each in Peace, Literature and Physiology or Medicine. Wikipedia.

Dholakia K.,University of St. Andrews | Zemanek P.,Academy of Sciences of the Czech Republic
Reviews of Modern Physics | Year: 2010

The light-matter interaction has been at the heart of major advances from the atomic scale right to the microscopic scale over the past four decades. Confinement by light, embodied by the area of optical trapping, has had a major influence across all of the natural sciences. However, an emergent and powerful topic within this field that has steadily merged but not gained much recognition is optical binding: the importance of exploring the optically mediated interaction between assembled objects that can cause attractive and repulsive forces and dramatically influence the way they assemble and organize themselves. This offers routes for colloidal self-assembly, crystallization, and organization of templates for biological and colloidal sciences. In this Colloquium, this emergent area is reviewed looking at the pioneering experiments in the field and the various theoretical approaches that aim to describe this behavior. The latest experimental studies in the field are reviewed and theoretical approaches are now beginning to converge to describe the binding behavior seen. Recent links between optical binding and nonlinearity are explored as well as future themes and challenges. © 2010 The American Physical Society. Source

Boyd I.L.,University of St. Andrews
Science | Year: 2012

Ecological models have limited predictive power, but can provide insights into what makes an ecosystem vulnerable to disturbance. Source

Nolan S.P.,University of St. Andrews
Accounts of Chemical Research | Year: 2011

Gold has emerged as a powerful synthetic tool in the chemists arsenal. From the early use of inorganic salts such as AuCl and AuCl3 as catalysts, the field has evolved to explore ligands that fine-tune reactivity, stability, and, more recently, selectivity in gold-mediated processes. Substrates generally contain alkenes or alkynes, and they usually involve straightforward protocols in air with solvents that can oftentimes be of technical grade. The actual catalytic species is the putative cationic gold(I) complex [Au(L)]+ (where L is a phosphorus-based species or N-heterocyclic carbene, NHC). The early gold systems bearing phosphine and phosphite ligands provided important transformations and served as useful mechanistic probes. More recently, the use of NHCs as ligands for gold has rapidly gained in popularity. These two-electron donor ligands combine strong f-donating properties with a steric profile that allows for both stabilization of the metal center and enhancement of its catalytic activity. As a result, the gold-NHC complexes have been used as well-defined precatalysts and have permitted the isolation of reactive single-component systems that are now used instead of the initial [Au(L)Cl]/silver salt method. Because some are now commercially available, NHC-containing gold(I) complexes are gathering increasing interest.In this Account, we describe the chronological development of this chemistry in our laboratories, highlighting the advantages of this family of gold complexes and reviewing their synthesis and applications in catalysis. We first outline the syntheses, which are straightforward. The complexes generally exhibit high stability, allowing for indefinite storage and easy handling. We next consider catalysis, particularly examining efficacy in cycloisomerization, other skeletal rearrangements, addition of water to alkynes and nitriles, and C-H bond activation. These processes are quite atom-economical, and in the most recent C-H reactions the only byproduct is water. State-of-the-art methodology now involves single-component catalysts, precluding the need for costly silver co-catalysts. Remarkably, the use of an NHC as a supporting ligand has permitted the isolation of [Au(L)(S)]+ species (where S is a solvent molecule such as a nitrile), which can act as single-component catalysts. Some improvements are still needed, as the single components are most often synthesized with a silver reagent. Owing to the stabilizing effect of NHC coordination, some NHC-containing systems can catalyze extremely challenging reactions (at temperatures as high as 140 A°C) and react at very low loadings of gold (ppm levels). Our latest developments deal with C-H bond functionalization and hold great promise.We close with a selection of important developments by the community with gold-NHC complexes. As demonstrated by the turns and twists encountered during our own journey in the gold-NHC venture, the chemistry described here, combining fundamental organometallic, catalytic, and organic methodology, remains rich in opportunities, especially considering that only a handful of gold(I) architectures has been studied. We hope this Account will encourage young researchers to explore this emerging area, as the adage the more you do, the more you have to do surely holds true in gold-mediated catalysis. © 2010 American Chemical Society. Source

Walton J.C.,University of St. Andrews
Accounts of Chemical Research | Year: 2014

ConspectusSelective syntheses are now available for compounds of many classes, based on C-centered radicals, exploiting a diverse range of mechanisms. The prospect for chemistry based around N- and O-centered radicals is probably more favorable because of the importance of heterocycles as biologically active materials. Heteroradical chemistry is still comparatively underdeveloped due to the need for safe and easy ways of generating them. Oxime esters appeared promising candidates to meet this need because literature reports and our EPR spectroscopic examinations showed they readily dissociated on photolysis with production of a pair of N- and O-centered radicals. It soon became apparent that a whole suite of benign oxime-containing molecules could be pressed into service. The bimodality of the oxime motif meant that by suitable choice of functionality the reactions could be directed to yield selectively products from either the N-centered radicals or from the O-centered radicals.We found that on one hand photolyses of acetophenone oxime esters of carboxylic acids yielded alicyclics. On the other hand, aromatic and heteroaromatic acyl oximes (as well as dioxime oxalates) afforded good yields of phenanthridines and related heterocycles. Easily prepared oxime oxalate amides released carbamoyl radicals, and pleasingly, β-lactams were thereby obtained. Oxime carbonates and oxime carbamates, available via our novel 1,1'-carbonyldiimidazole (CDI)-based preparations, were accessible alternatives for iminyl radicals and hence for phenanthridine preparations. In their second modes, these compounds proved their value as precursors for exotic alkoxycarbonyloxyl and carbamoyloxyl radicals.Microwave-assistance was shown to be a particularly convenient procedure with O-phenyl oxime ethers. The iminyl radicals generated from such precursors with alkene, alkyne, and aromatic acceptor substituents furnished pyrrole, quinoline, phenanthridine, benzonaphthiridine, indolopyridine, and other systems. Microwave irradiations with 2-(aminoaryl)alkanone O-phenyl oximes enabled either dihydroquinazolines or quinazolines to be obtained in very good yields.The fine quality of the EPR spectra, acquired during photolyses of all the O-carbonyl oxime types, marked this as an important complement to existing ways of obtaining such spectra in solution. Quantifications enabled SARs to be obtained for key reaction types of N- and O-centered radicals, thus putting mechanistic chemistry in this area on a much firmer footing. Surprises included the inverse gem-dimethyl effect in 5-exo-cyclizations of iminyls and the interplay of spiro- with ortho-cyclization onto aromatics. Insights into unusual 4-exo-cyclizations of carbamoyl radicals showed the process to be more viable than pent-4-enyl 4-exo-ring closure. Another surprise was the magnitude of the difference in CO2 loss rate from alkoxycarbonyloxyl radicals as compared with acyloxyl radicals. Their rapid 5-exo-cyclization was charted, as was their preferred spiro-cyclization onto aromatics. The first evidence that N-monosubstituted carbamoyloxyls had finite lifetimes was also forthcoming.It is evident that oxime derivatives have excellent credentials as reagents for radical generation and that there is ample room to extend their applications to additional radical types and for further heterocycle syntheses. There is also clear scope for the development of preparative procedures based around the alkoxyl and aminyl radicals that emerge downstream from oxime carbonate and oxime carbamate dissociations. © 2014 American Chemical Society. Source

Vishwanath D.,University of St. Andrews
Psychological Review | Year: 2014

Humans can obtain an unambiguous perception of depth and 3-dimensionality with 1 eye or when viewing a pictorial image of a 3-dimensional scene. However, the perception of depth when viewing a real scene with both eyes is qualitatively different: There is a vivid impression of tangible solid form and immersive negative space. This perceptual phenomenon, referred to as "stereopsis," has been among the central puzzles of perception since the time of da Vinci. After Wheatstone's invention of the stereoscope in 1838, stereopsis has conventionally been explained as a byproduct of binocular vision or visual parallax. However, this explanation is challenged by the observation that the impression of stereopsis can be induced in single pictures under monocular viewing. Here I propose an alternative hypothesis that stereopsis is a qualitative visual experience related to the perception of egocentric spatial scale. Specifically, the primary phenomenal characteristic of stereopsis (the impression of "real" separation in depth) is proposed to be linked to the precision with which egocentrically scaled depth (absolute depth) is derived. Since conscious awareness of this precision could help guide the planning of motor action, the hypothesis provides a functional account for the important secondary phenomenal characteristics associated with stereopsis: the impression of interactability and realness. By linking stereopsis to a generic perceptual attribute, rather than a specific cue, it provides a potentially more unified account of the variation of stereopsis in real scenes and pictures and a basis for understanding why we can perceive depth in pictures despite conflicting visual signals. © 2014 American Psychological Association. Source

Discover hidden collaborations