Electronic decoherence following photoionization: full quantum-dynamical treatment of the influence of nuclear motion

Photoionization using attosecond pulses can lead to the formation of coherent superpositions of the electronic states of the parent ion. However, ultrafast electron ejection triggers not only electronic but also nuclear dynamics---leading to electronic decoherence, which is typically neglected on time scales up to tens of femtoseconds. We propose a full quantum-dynamical treatment of nuclear motion in an adiabatic framework, where nuclear wavepackets move on adiabatic potential energy surfaces expanded up to second order at the Franck-Condon point. We show that electronic decoherence is caused by the interplay of a large number of nuclear degrees of freedom and by the relative topology of the potential energy surfaces. Application to $\mathrm{H_2O}$, paraxylene, and phenylalanine shows that an initially coherent state evolves to an electronically mixed state within just a few femtoseconds. In these examples the fast vibrations involving hydrogen atoms do not affect electronic coherence at short times. Conversely, vibrational modes involving the whole molecular skeleton, which are slow in the ground electronic state, quickly destroy it upon photoionization.Comment: 18 pages, 8 figure

Towards attochemistry: Control of nuclear motion through conical intersections and electronic coherences

The effect of nuclear dynamics and conical intersections on electronic coherences is investigated employing a two-state, two-mode linear vibronic coupling model. Exact quantum dynamical calculations are performed using the multi-configuration time-dependent Hartree method (MCTDH). It is found that the presence of a non-adiabatic coupling close to the Franck-Condon point can preserve electronic coherence to some extent. Additionally, the possibility of steering the nuclear wavepackets by imprinting a relative phase between the electronic states during the photoionization process is discussed. It is found that the steering of nuclear wavepackets is possible given that a coherent electronic wavepacket embodying the phase difference passes through a conical intersection. A conical intersection close to the Franck-Condon point is thus a necessary prerequisite for control, providing a clear path towards attochemistry.Comment: 12 pages, 3 figure

Mental Reactions of Childbirth

1. The occurrence of psychiatric conditions in association with gestation and particularly the puerperium is greater than might be expected by chance, and the mean age at which these reactions occur is about 30. 2. The parapartum period is associated with physiological changes which have also been associated with mental changes in psychiatric reports. 3. Changes in the nervous system occur in the parapartum period and are illustrated by changes in the course of nervous and psychosomatic conditions. 4. Toxaemia of pregnancy, which is a common complication of parturition, involves the nervous system, 5. Childbirth is an important psychological event per se as is seen by its influence on the male associated with it, 6. A group of normal mothers studied in two maternity hospitals showed conceptual impairment, and associated hysterical and depressive traits and heightened siiggestibilitir in the puerperium. 7. A group of parapartum neurotics studied in out-patients departments and mental hospitals had predominantly hysterical and depressive reactions to chronic interpersonal difficulties no longer contained by the weakened integration associated with the parapartum period. A history of neuropathy in childhood, of frigidity since marriage, and a tainted family history was frequently found. 8. a group of parapartum psychotics of low average intelli- gence had predominantly confusional, depressive and catatonic reactions to physical difficulties in parturition. A tainted family history was found equally commonly but psychological problems were relatively infrequently discovered

Simulated XUV Photoelectron Spectra of THz-pumped Liquid Water

Highly intense, sub-picosecond terahertz (THz) pulses can be used to induce ultrafast temperature jumps (T-jumps) in liquid water. A supercritical state of gas-like water with liquid density is established, and the accompanying structural changes are expected to give rise to time-dependent chemical shifts. We investigate the possibility of using extreme ultraviolet (XUV) photoelectron spectroscopy as a probe for ultrafast dynamics induced by sub-picosecond THz pulses of varying intensities and frequencies. To this end, we use ab initio methods to calculate photoionization cross sections and photoelectron energies of (H2O)$_{20}$ clusters embedded in an aqueous environment represented by point charges. The cluster geometries are sampled from ab initio molecular dynamics simulations modeling the THz-water interactions. We find that the peaks in the valence photoelectron spectrum are shifted by up to 0.4 eV after the pump pulse, and that they are broadened with respect to unheated water. The shifts can be connected to structural changes caused by the heating, but due to saturation effects they are not sensitive enough to serve as a thermometer for T-jumped water

A homotopy-theoretic view of Bott-Taubes integrals and knot spaces

We construct cohomology classes in the space of knots by considering a bundle over this space and "integrating along the fiber" classes coming from the cohomology of configuration spaces using a Pontrjagin-Thom construction. The bundle we consider is essentially the one considered by Bott and Taubes, who integrated differential forms along the fiber to get knot invariants. By doing this "integration" homotopy-theoretically, we are able to produce integral cohomology classes. We then show how this integration is compatible with the homology operations on the space of long knots, as studied by Budney and Cohen. In particular we derive a product formula for evaluations of cohomology classes on homology classes, with respect to connect-sum of knots.Comment: 32 page

Dissection and Exposure of the Whole Course of Deep Nerves in Human Head Specimens after Decalcification

The whole course of the chorda tympani nerve, nerve of pterygoid canal, and facial nerves and their relationships with surrounding structures are complex. After reviewing the literature, it was found that details of the whole course of these deep nerves are rarely reported and specimens displaying these nerves are rarely seen in the dissecting room, anatomical museum, or atlases. Dissections were performed on 16 decalcified human head specimens, exposing the chorda tympani and the nerve connection between the geniculate and pterygopalatine ganglia. Measurements of nerve lengths, branching distances, and ganglia size were taken. The chorda tympani is a very fine nerve (0.44 mm in diameter within the tympanic cavity) and approximately 54 mm in length. The mean length of the facial nerve from opening of internal acoustic meatus to stylomastoid foramen was 52.5 mm. The mean length of the greater petrosal nerve was 26.1 mm and nerve of the pterygoid canal was 15.1 mm

Impact of a Middle School 4-H Science Camp on College Aspirations of Alumni

This article reports on an alumni study of middle school participants in a university-based science camp; at the time of the study the youth were completing their junior or senior year of high school. The science- and technology-intensive program was set in an intentionally designed positive youth development context. The camp was free to youth who were members of populations underrepresented in science and technology careers or were from underserved areas of the state. The alumni fulfilled the camp goal that they plan to attend college after high school. The majority reported planning to get a professional or advanced degree

Optomechanical self-structuring in cold atomic gases

The rapidly developing field of optomechanics aims at the combined control of optical and mechanical (solid-state or atomic) modes. In particular, laser cooled atoms have been used to exploit optomechanical coupling for self-organization in a variety of schemes where the accessible length scales are constrained by a combination of pump modes and those associated to a second imposed axis, typically a cavity axis. Here, we consider a system with many spatial degrees of freedom around a single distinguished axis, in which two symmetries - rotations and translations in the plane orthogonal to the pump axis - are spontaneously broken. We observe the simultaneous spatial structuring of the density of a cold atomic cloud and an optical pump beam. The resulting patterns have hexagonal symmetry. The experiment demonstrates the manipulation of matter by opto-mechanical self-assembly with adjustable length scales and can be potentially extended to quantum degenerate gases.Comment: 20 pages, 6 figure

PENGLIBATAN POLITIK KOMUNITI PERIBUMI ISLAM DI LABUAN SEMASA ZAMAN PENJAJAHAN BRITISH, 1946-1963

Tema kajian berkenaan penglibatan politik komuniti peribumi Islam di Labuan penting dalam mengisi kelompangan sejarah politik Labuan. Persoalan-persoalan kajian yang cuba dijawab adalah: apakah peranan politik yang dimainkan oleh komuniti peribumi Islam semasa zaman penjajahan British, 1946- 1963? Apakah faktor-faktor yang mempengaruhi penglibatan mereka dalam arena politik Labuan dan bagaimana pula reaksi British terhadap penglibatan tersebut? Tiga objektif utama kajian adalah: menghuraikan penglibatan komuniti peribumi Islam dalam arena politik Labuan dari tahun 1946-1963, menganalisis peranan yang dimainkan oleh komuniti peribumi Islam dalam pemerintahan kolonial British dan menilai dasar pihak British terhadap penglibatan politik pemimpin-pemimpin komuniti peribumi Islam. Kajian ini menggunakan pendekatan kualitatif yang melibatkan pengumpulan data melalui perpustakaan konvensional (sumber arkib) dan temu bual mendalam. Kaedah kritikan dalaman dan luaran turut diaplikasikan dalam menilai, menginterpretasi dan menganalisis sumber-sumber primer, sekunder dan lisan yang diperolehi. Tema-tema utama kajian pula dihuraikan secara deskriptif dan kronologikal. Dapatan kajian mendapati bahawa penglibatan peribumi Islam dalam arena politik Labuan dapat dibahagikan dalam dua fasa iaitu fasa pertama pada tahun 1946-1960 dan fasa kedua pada tahun 1961-1963. Penglibatan komuniti peribumi Islam dalam politik pada fasa pertama dipengaruhi oleh keinginan untuk memperjuangkan agama Islam, hak identiti etnik, dan kepentingan etnik kolektif komuniti peribumi Islam di Labuan. Manakala, pada fasa kedua pula, penglibatan politik komuniti peribumi Islam dimotivasikan oleh perjuangan untuk mendapatkan hak berpolitik dan tuntutan kemerdekaan dalam gagasan Malaysia. Didapati bahawa British bersifat terbuka terhadap kesedaran berpolitik yang ditunjukkan oleh pemimpin-pemimpin komuniti peribumi Islam. Peluang juga diberikan kepada pemimpin-pemimpin peribumi Islam di Labuan untuk terlibat dalam aktiviti berpolitik. Namun, penglibatan politik komuniti peribumi Islam di Labuan adalah terhad kerana pemimpin-pemimpin komuniti peribumi Islam tidak diberikan peranan yang signifikan dalam pentadbiran British