The vibrational predissociation spectroscopy of hydrogen cluster ions

The first infrared spectra of protonated hydrogen clusters in the gas phase have been observed. Predissociation spectra were taken with a tandem mass spectrometer: mass selected hydrogen cluster ions were irradiated inside a rf ion trap by a tunable infrared laser, and the fragment ions created by photodissociation of the clusters were mass selected and detected. Spectra for each product channel were measured by counting fragment ions as a function of laser frequency. Low resolution spectra (Deltanu=10 cm^−1) in the region from 3800 to 4200 cm^−1 were observed for the ions H + 5, H + 7, and H + 9 at 3910, 3980, and 4020 cm−1, respectively. A band was also observed for H + 5 at 3532 cm^−1. No rotational structure was resolved. The frequencies of the band maxima agree well with the frequencies predicted by previous ab initio calculations for the highest modes

General circulation in the atmosphere of Venus driven by polar and diurnal variations of surface temperature

Mathematical model for Venus atmosphere circulation pattern determined by polar and diurnal temperature variation

Infrared spectra of the cluster ions H7O⁺₃·H2 and H9O⁺₄·H2

Infrared spectra of hydrated hydronium ions weakly bound to an H2 molecule, specifically H7O + 3 ·H2 and H9O + 4 ·H2, have been observed. Mass-selected parent ions, trapped in a radio frequency ion trap, are excited by a tunable infrared laser; following absorption, the complex predissociates with loss of the H2, and the resulting fragment ions are detected. Spectra have been taken from 3000 to 4000 cm^−1, with a resolution of 1.2 cm^−1. They are compared to recent theoretical and experimental spectra of the hydronium ion hydrates alone. Binding an H2 molecule to these clusters should only weakly perturb their vibrations; if so, our spectra should be similar to spectra of the hydrated hydronium ions H7O + 3 and H9O + 4

Investigating the Physical Origin of Unconventional Low-Energy Excitations and Pseudogap Phenomena in Cuprate Superconductors

We investigate the physical origin of unconventional low-energy excitations in cuprate superconductors by considering the effect of coexisting competing orders (CO) and superconductivity (SC) and of quantum fluctuations and other bosonic modes on the low-energy charge excitation spectra. By incorporating both SC and CO in the bare Green's function and quantum phase fluctuations in the self-energy, we can consistently account for various empirical findings in both the hole- and electron-type cuprates, including the excess subgap quasiparticle density of states, ``dichotomy'' in the fluctuation-renormalized quasiparticle spectral density in momentum space, and the occurrence and magnitude of a low-energy pseudogap being dependent on the relative gap strength of CO and SC. Comparing these calculated results with experiments of ours and others, we suggest that there are two energy scales associated with the pseudogap phenomena, with the high-energy pseudogap probably of magnetic origin and the low-energy pseudogap associated with competing orders.Comment: 10 pages, 5 figures. Invited paper for the 2006 Taiwan International Conference on Superconductivity. Correspondence author: Nai-Chang Yeh (e-mail: [email protected]

Doing care work for older people : work identities, motivations and barriers to job satisfaction

There is an increasing care demand for care home workers have a significant role in meeting residents’ care needs from the admission to a care home up to the end of life. However, there is persistent high care home worker turnover that can negatively impact the quality of care residents receive and care workers’ wellbeing. This thesis aimed to explore care home workers’ perceptions, experiences, and motivations of continuing their work role through the lens of self-determination theory (SDT). The first qualitative study (n=22) explored care workers’ perceptions and experiences of providing care for residents from the admission to the care home up to the end of life. Thematic analysis was used to analyse the data. Participants’ accounts reflected that social interaction had a significant role in facilitating the development of their work identities and encouraging them to remain employed in the care homes. The second study (quantitative, n=207) that built on the findings of study 1 investigated how care home workers’ perceptions towards their work roles, psychosocial attributes, psychological needs, and motivation influence their organisational commitment and job satisfaction using structural equation modelling. The study suggested a contextual significance of satisfying care workers’ psychological needs which then shapes their motivation and influences their organisational commitment and job satisfaction. The third study (qualitative, n=10) that complimented the findings of study 1 and 2 was to understand managers’ perspectives on care workers’ support needs and how they provide support to their care workers in the care homes using thematic analysis. Participants’ accounts reflected that meeting care workers’ autonomy need and enhance the effectiveness of communication between managers and care workers helped convey care home values and the meanings of care work to care workers, foster a positive work environment, and improve teamwork. This thesis contributes to the theoretical understanding of care workers’ work identities and motivations of continuing their care worker role. As a career that is dominated by people and interactions with people, social interaction has a significant role in facilitating care workers to establish their work identities and implement role expectations and the meanings of care work in their care practice, satisfying their psychological needs at work, and experiencing a higher organisational commitment and job satisfaction. This thesis highlights the significance of the consistency in management practices which helps eliminate the incongruences care home workers experienced between their work identities and the real job of caring and facilitate the development and maintenance of a stable and positive care home culture. This thesis has the potential to inform or devise interventions with evidence-based information to enhance care workers’ retention and wellbeing

A parallel VLSI architecture for a digital filter of arbitrary length using Fermat number transforms

A parallel architecture for computation of the linear convolution of two sequences of arbitrary lengths using the Fermat number transform (FNT) is described. In particular a pipeline structure is designed to compute a 128-point FNT. In this FNT, only additions and bit rotations are required. A standard barrel shifter circuit is modified so that it performs the required bit rotation operation. The overlap-save method is generalized for the FNT to compute a linear convolution of arbitrary length. A parallel architecture is developed to realize this type of overlap-save method using one FNT and several inverse FNTs of 128 points. The generalized overlap save method alleviates the usual dynamic range limitation in FNTs of long transform lengths. Its architecture is regular, simple, and expandable, and therefore naturally suitable for VLSI implementation