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T H Lu

Publications and source records attributed to T H Lu.

At least 19 recordsLinked to original sources
PubMed2006

Wave functions with localizations on classical periodic orbits in weakly perturbed quantum billiards.

We analytically investigate quantum wave functions with localizations on classical periodic orbits (POs) in the circular billiards. We construct the coherent states which are the coherent superpositions of nearly degenerate eigenstates and found to be localized around single classical POs. With the constructed coherent states, we can analytically express the mesoscopic eigenstates in the weakly perturbed systems, which are found to be localized on the ensemble of classical POs. Furthermore, these coherent states can be utilized to study the quantum vortex structures in quantum billiards.

Journal Article↗
PubMed2006

Certifying diabetes-related cause-of-death: a comparison of inappropriate certification statements in Sweden, Taiwan and the USA.

AIMS/HYPOTHESIS: The aim of this study was to assess differences in the certification practices of physicians in Sweden, Taiwan and the USA with regard to diabetes-related cause-of-death (COD) statements. METHODS: Multiple-cause-of-death data from Sweden (2000), Taiwan (2001) and the USA (2001) were used for this study. All deaths with mention of diabetes anywhere on the death certificate were extracted for analysis. Two types of inappropriate COD statements were: (1) reporting two or more diagnoses per line; and (2) entering an incorrect causal sequence among reported diagnoses. RESULTS: Of those deaths in which diabetes was reported in Part I of the death certificate, American physicians (19%) were less likely to report two or more diagnoses per line than physicians in Sweden (46%) and Taiwan (56%). On the other hand, Swedish physicians (5%) were less likely to report incorrect causal sequences than were their counterparts in Taiwan (21%) and the USA (28%). CONCLUSIONS/INTERPRETATION: These findings reveal substantial differences in diabetes-related COD statements among physicians in Sweden, Taiwan and the USA, implying that caution should be used when interpreting differences in mortality statistics between these countries.

Automation↗
PubMed2006

Devil's staircase in three-dimensional coherent waves localized on Lissajous parametric surfaces.

We experimentally demonstrate the significance of the longitudinal-transverse coupling in the mesoscopic regime by using a high-Q laser resonator as an analog experiment. The longitudinal-transverse coupling is found to lead to the three-dimensional (3D) coherent waves that are localized on the parametric surfaces with Lissajous transverse patterns. More strikingly, experimental results reveal that the mode locking of the 3D coherent states forms a nearly complete Devil's staircase with the hierarchical ordering.

Journal Article↗
PubMed2006

Manifestation of weak localization and long-range correlation in disordered wave functions from conical second harmonic generation.

We experimentally demonstrate that the near-field patterns of conical second harmonic generation of a laser in random domain structures can be used to explore the spatial structure of two-dimensional disordered wave functions with weak localization. The statistics of the experimental near-field patterns agree very well with the theoretical distributions. In addition to the short-range correlation, the localization effects are found to contribute a nearly constant value to the long-range correlation. The result of this Letter also confirms the possibility of using conical second harmonic generation as a diagnostic tool for topographical characterization of crystals.

Journal Article↗
PubMed2006

Observation of spatially coherent polarization vector fields and visualization of vector singularities.

We present experimental observations of polarization vector fields from a highly isotropic microchip laser with a large Fresnel number. The experimental polarization vector field leads to complex entanglement of spatial structures and polarization states. We theoretically derive the representation of generalized coherent states to reconstruct the experimental polarization-resolved patterns. The analytical and precise reconstruction enables the vector singularities to be clearly visualized.

Journal Article↗
PubMed2005

Quantum signatures of nonlinear resonances in mesoscopic systems: efficient extension of localized wave functions.

We investigate the quantum signatures of classical nonlinear resonances by making the analytic connection between the quantum wave functions and the classical periodic orbits for the uncoupled systems. It is found that the highly efficient extension of the localized coherent states within the classical caustics is an intriguing phenomenon in mesoscopic systems with nonlinear resonances. With the theoretical analysis, we experimentally demonstrate that the laser resonator with an intracavity saturable absorber can be employed to visualize the wave patterns analogous to the quantum wave functions associated with Fermi resonance.

Journal Article↗
PubMed2005

Tuberculosis mortality trends in Taiwan: a resurgence of non-respiratory tuberculosis.

SETTING: Population-based study in Taiwan. OBJECTIVE: To determine the tuberculosis (TB) mortality trends in Taiwan by site and age. DESIGN: Mortality data for the years 1972 to 2001 were used to calculate the age/site-specific mortality rate (deaths per 100000 population). The year of change in the slope of mortality trends was estimated by iterative piecewise regression analysis. RESULTS: A levelling off in mortality trends was noted in the late 1980s for all age groups except those aged 75 and above. Except in the age group 25-44 years, the trends in respiratory TB mortality showed a smooth decline. However, for non-respiratory TB mortality, a reversal of the decline was noted for all age groups since 1994-1995. A twofold increase in the number of deaths from central nervous system (CNS) and 'other' TB was noted. A marked increase in the number of deaths from old TB was noted since 1992-1996. CONCLUSION: TB mortality trends in Taiwan have not declined as expected over the past decade. The slowing down of the decline in TB mortality was mainly attributable to a levelling off of respiratory TB mortality in the age group 25-44 and a reversal of non-respiratory TB mortality trends, especially in the 25-44 and > or =65 years age groups.

Adolescent↗
PubMed2001

A linear cyclic oximate-bridged tetracopper(II) complex.

The crystal structure of the title complex, tetrakis[mu-6-amino-3-methyl-4-azahex-3-en-2-one oximato(1-)-kappa4N,N',N":O]tetracopper(II) tetraperchlorate 0.6-hydrate, [Cu4(C6H12N3O)4](ClO4)4*0.6H2O, shows the cation to be an oximate-bridged tetramer composed of four 6-amino-3-methyl-4-azahex-3-en-2-one oxime ligands and four copper(II) ions and to have crystallographically imposed 4 symmetry. Each Cu(II) atom is four-coordinated by the three N atoms of one oxime ligand and by the O atom of another oxime ligand in a distorted square-planar geometry.

Journal Article↗
PubMed2001

(Nitro-kappaN)[2-(phenyldiazenyl-kappaN2)-pyridine-kappaN](2,2':6',2''-terpyridine-kappa3N)ruthenium(II) tetrafluoroborate.

The Ru-N bond distances in the title complex, [Ru(NO(2))(C(11)H(9)N(3))(C(15)H(11)N(3))]BF(4) or [Ru(NO(2))(tpy)(azpy)]BF(4), [tpy is 2,2':6',2"-terpyridine and azpy is 2-(phenylazo)pyridine], are Ru-N(py) 2.063 (4), Ru-N(azo) 2.036 (4), Ru-N(nitro) 2.066 (3) A, and Ru-N(tpy) 2.082 (4), 1.982 (3) and 2.074 (4) A. The azo N atom is trans to the nitro group. The azo N=N bond length is 1.265 (5) A, which is the shortest found in such complexes to date. This indicates a multiple bond between Ru and the N atom of the nitro group, and pi-backbonding [dpi(Ru) --> pi*(azo)] is decreased.

Journal Article↗
PubMed2001

Factors associated with errors in death certificate completion. A national study in Taiwan.

To identify characteristics of certifying physicians and the deceased that are associated with errors in death certificate completion in Taiwan, we retrospectively reviewed 4123 systematically sampled death certificates issued in 1994. Multivariate analyses were used to assess the associations of various characteristics of the certifying physicians and the deceased with four types of error. Of the 4123 death certificates reviewed, 2525 (61%) were completed correctly. In 289 (7%), only the mechanism(s) of death was given (Major Error 1); in 146 (4%), multiple causal sequences were given in part I (Major Error 2); in 800 (19%), a single causal sequence was given but was not specific enough (Minor Error 1); and in 363 (9%), a single causal sequence was given but the order was incorrect (Minor Error 2). Multiple logistic regression analyses revealed that the probability of error in death certification increased as the age of the deceased increased, the age of the certifier decreased, and the level of the hospital decreased. These findings suggest that training in death certificate completion should focus on younger certifiers and those working at lower level teaching hospitals and nonteaching hospitals. Given the high rate of Minor Error 1, physicians should be reminded to state information as specifically as possible to render cause-of-death statistics more informative.

Adult↗
PubMed2001

Diversity in death certification: a case vignette approach.

Previous studies have revealed high rates of errors in death certification, but few have discussed the nature of these errors. To explore the diversity among physicians in death certification and its relationship with the complexity of the causal sequence of death, we asked 145 physicians attending a continuing medical education course to complete the cause-of-death section on dummy death certificates of four case vignettes. The difficulty in determining the causal sequence of death varied from relatively simple to complex. Variations in death certification were classified according to wording, diagnostic semantics, combinations of expressions, correctness of certification format, and concordance with the referent underlying cause of death (UCOD). Given the same case history information, physicians showed great variation in wording and diagnostic semantics in death certification. The rates of correct certification format and concordance with referent UCOD varied with the level of complexity of the causal sequence of death. The greatest source of diversity was choosing between an acute condition of a chronic disease and the chronic disease itself, and between competing prominent comorbidities. Experience in death certification was significantly associated with correct certification format but not with concordance with referent UCOD. Knowledge of death certification was not associated with correct certification format or concordance with referent UCOD. Our findings indicate that the traditional concept of UCOD tabulation and using a single standard ICD code in evaluating the quality of death certification oversimplifies a complex situation. Variations in death certification, especially the selection of UCOD, were due to differences in interpreting the information rather than differences in knowledge of death certification.

Acute Disease↗
PubMed2001

Comparison of official coders versus physician panel in assignment of underlying cause of death.

BACKGROUND AND PURPOSE: In outcome analyses of clinical trials and mortality follow-up studies, the underlying cause of death (UCOD) is commonly assigned either by official coders or by a panel of physicians. We evaluated the validity of UCOD assigned by official coders by comparison with the assignments of a panel of physicians who reviewed the available medical records of the deceased. METHODS: The comparisons focused on deaths occurring from October 1995 through June 1998 in a series of residents in a veterans home. Because of limited resources, only the first 104 deaths that occurred during the study period were included. Agreement rate, sensitivity, specificity, and kappa statistics were calculated to assess the consistency of coder versus physician panel assignment of UCOD by selected main causes of death. For 32 of the 104 deaths, the panel concluded that the information obtained from medical records was insufficient to determine the UCOD, and the following analyses were confined to the other 72 deaths. RESULTS: For the 72 deaths considered by the panel to have sufficient information to determine UCOD, all four physicians agreed on a single UCOD in 50 (69%) cases, while three or four agreed in 66 (92%) cases. A consensus was reached in cases with disagreement. The two procedures completely agreed in 40 (56%) of the deaths. For general category UCOD, the kappa value was high for cancer (0.83) and cardiovascular disease (CVD, 0.73) but only moderate for pulmonary disease (PD, 0.60). When the UCOD assigned by the panel was used as the gold standard, official coders showed relatively low sensitivity for correct determination of UCOD in cases of CVD (0.76) compared with cancer (0.86) and PD (0.80). CONCLUSIONS: Given the high inter-physician consistency and the relatively low sensitivity of official coders in assigning CVD as the UCOD, we conclude that the use of clinical review panels would provide more accurate UCOD assignments for use in outcome analyses in mortality follow-up studies and clinical trials in Taiwan.

Aged↗