Gene-environment interactions and aging visual function: a classical twin study.

OBJECTIVE:
To elucidate the contribution of environmental versus genetic factors to the significant losses in visual function associated with normal aging.
DESIGN:
A classical twin study.
PARTICIPANTS:
Forty-two twin pairs (21 monozygotic and 21 dizygotic; age 57-75 years) with normal visual acuity recruited through the Australian Twin Registry.
METHODS:
Cone function was evaluated by establishing absolute cone contrast thresholds to flicker (4 and 14 Hz) and isoluminant red and blue colors under steady state adaptation. Adaptation dynamics were determined for both cones and rods. Bootstrap resampling was used to return robust intrapair correlations for each parameter.
MAIN OUTCOME MEASURES:
Psychophysical thresholds and adaptational time constants.
RESULTS:
The intrapair correlations for all color and flicker thresholds, as well as cone absolute threshold, were significantly higher in monozygotic compared with dizygotic twin pairs (P<0.05). Rod absolute thresholds (P = 0.28) and rod and cone recovery rate (P = 0.83; P = 0.79, respectively) did not show significant differences between monozygotic and dizygotic twins in their intrapair correlations, indicating that steady-state cone thresholds and flicker thresholds have a marked genetic contribution, in contrast with rod thresholds and adaptive processes, which are influenced more by environmental factors over a lifetime.
CONCLUSIONS:
Genes and the environment contribute differently to important neuronal processes in the retina and the role they may play in the decline in visual function as we age. Consequently, retinal structures involved in rod thresholds and adaptive processes may be responsive to appropriate environmental manipulation. Because the functions tested are commonly impaired in the early stages of age-related macular degeneration, which is known to have a multifactorial etiology, this study supports the view that pathogenic pathways early in the disease may be altered by appropriate environmental intervention.

Methods and code for 'classical' age-modelling of radiocarbon sequences.

Age–depth models form the backbone of most palaeoenvironmental studies. However, procedures for constructing chronologies vary between studies, they are usually not explained sufficiently, and some are inadequate for handling calibrated radiocarbon dates. An alternative method based on importance sampling through calibrated dates is proposed. Dedicated R code is presented which works with calibrated radiocarbon as well as other dates, and provides a simple, systematic, transparent, documented and customizable alternative. The code automatically produces age–depth models, enabling exploration of the impacts of different assumptions (e.g., model type, hiatuses, age offsets, outliers, and extrapolation).

The Creative Life of Law: Improvisation, Between Tradition and Suspicion

Originally applying solely to chefs, waiters, dishwashers and the like, New York City (NYC) regulations governing cabaret employees were altered in 1943 to include musicians and entertainers, who until the late 1960’s would be required to hold a NYC Cabaret Employee’s Identification Card. The introduction of these notorious “police cards” occurred roughly contemporaneously to the emergence in after-hours night clubs in Harlem of a new and supposedly “wild”, improvisatory brand of jazz: bebop. This article adds to the many rather practical theories on why these cards were introduced a more abstract discussion coined in terms of the relationship between suspicion and tradition and focusing on differing essences of law and improvisatory jazz. While law breathes tradition and is suspicious of improvisation and unpredictability, the converse is true of jazz. Allusion to tradition in jazz improvisation is often viewed as a betrayal of its creative and spontaneous nature. And yet it is only through its departure from the stable transmission of past meaning that improvisation gains meaning. Law, in contrast, while appearing to be entirely composed of tradition, to transmit some sort of determinate and fixed meaning, is constantly betraying itself. As no two legal actions can be exactly the same, judges must improvise on tradition and past precedent every time they are asked to decide a case. Law can thus neither dispense with nor be completely determined by tradition. The legal decision instead lies on the border between what it “is” and what it otherwise could be and every judicial act is, in some sense, a species of improvisation. This article uses the cabaret cards to explore this uncertain terrain between law and improvisation, between tradition and suspicion.

The Liedertheater of Wenzel and Mensching: Subversive Use of the Agitprop and Clowning Tradition in the GDR

The East German poet-clowns Hans-Eckardt Wenzel and Steffen Mensching rose to prominence during the GDR's (German Democratic Republic; Deutsche Demokratische Republik, DDR) Peaceful Revolution of autumn 1989 with their cabaret production Letztes aus der Da Da eR. A film adaptation of the production was made by Jörg Foth in 1990, which was finally released on DVD with English subtitles in the United Kingdom and North America in 2009 (Latest from the Da-Da-R). In light of this long-overdue interest in Wenzel & Mensching, this article will attempt to put the work of the duo in historical and aesthetic context. Their use of character, masks, music, and philosophy combined to create the distinctly grotesque world that constituted their Liedertheater performances.

Quasi-classical model of non-destructive wavepacket manipulation by intense ultrashort nonresonant laser pulses

A quasi-classical model (QCM) of nuclear wavepacket generation, modification and imaging by three intense ultrafast near-infrared laser pulses has been developed. Intensities in excess of 10(13) W cm(-2) are studied, the laser radiation is non-resonant and pulse durations are in the few-cycle regime, hence significantly removed from the conditions typical of coherent control and femtochemistry. The 1s sigma ground state of the D-2 precursor is projected onto the available electronic states in D-2(+) (1s sigma(g) ground and 2p sigma(u) dissociative) and D+ + D+ (Coulomb explosion) by tunnel ionization by an ultrashort 'pump' pulse, and relative populations are found numerically. A generalized non-adiabatic treatment allows the dependence of the initial vibrational population distribution on laser intensity to be calculated. The wavepacket is approximated as a classical ensemble of particles moving on the 1s sigma(g) potential energy surface (PES), and hence follow trajectories of different amplitudes and frequencies depending on the initial vibrational state. The 'control' pulse introduces a time-dependent polarization of the molecular orbital, causing the PES to be modified according to the dynamic Stark effect and the transition dipole. The trajectories adjust in amplitude, frequency and phase-offset as work is done on or by the resulting force; comparing the perturbed and unperturbed trajectories allows the final vibrational state populations and phases to be determined. The action of the 'probe' pulse is represented by a discrete internuclear boundary, such that elements of the ensemble at a larger internuclear separation are assumed to be photodissociated. The vibrational populations predicted by the QCM are compared to recent quantum simulations (Niederhausen and Thumm 2008 Phys. Rev. A 77 013404), and a remarkable agreement has been found. The applicability of this model to femtosecond and attosecond time-scale experiments is discussed and the relation to established femtochemistry and coherent control techniques are explored.

Ant-lore in Anglo-Saxon England

Two Old English versions of a sunshine prognostication survive in the mid-eleventh century Cambridge, Corpus Christi College 391, p. 713, and in a twelfth-century addition to Oxford, Bodleian Library, Hatton 115, 149v–150r. Among standard predictions promising joy, peace, blossom, abundance of milk and fruit, and a great baptism sent by God, one encounters an enigmatic prophecy which involves camels stealing gold from the ants. These gold-digging ants have a long pedigree, one which links Old English with much earlier literature and indicates the extent to which Anglo-Saxon culture had assimilated traditions of European learning. It remains difficult to say what is being prophesied, however, or to explain the presence of the passage among conventional predictions. Whether the prediction was merely a literary exercise or carried a symbolic implication, it must have originated in an ecclesiastical context. Its mixture of classical learning and vernacular tradition, Greek and Latin, folklore and Christian, implies an author with some knowledge of literary and scholarly traditions.