Biomedical subjects

D Kim

Publications and source records attributed to D Kim.

At least 55 records · Page 3Linked to original sources

PubMed2005

Branching fractions for psi(2S)-to-J/psi transitions.

We describe new measurements of the inclusive and exclusive branching fractions for psi(2S) transitions to J/psi using e(+)e(-) collision data collected with the CLEO detector operating at CESR. All branching fractions and ratios of branching fractions reported here represent either the most precise measurements to date or the first direct measurements. Indirectly and in combination with other CLEO measurements, we determine B(chi(cJ) --> gamma(J/psi)) and B[psi(2S) --> light hadrons].

Journal Article↗

PubMed2005

Spin-glass phase transition on scale-free networks.

We study the Ising spin-glass model on scale-free networks generated by the static model using the replica method. Based on the replica-symmetric solution, we derive the phase diagram consisting of the paramagnetic (P), ferromagnetic (F), and spin glass (SG) phases as well as the Almeida-Thouless line as functions of the degree exponent lambda, the mean degree K, and the fraction of ferromagnetic interactions r. To reflect the inhomogeneity of vertices, we modify the magnetization m and the spin-glass order parameter q with vertex- weights. The transition temperature T(c) (T(g)) between the P-F (P-SG) phases and the critical behaviors of the order parameters are found analytically. When 2 1/2, while it is in the SG phase at r=1/2. m and q decay as power-laws with increasing temperature with different lambda-dependent exponents. When lambda>3, the T(c) and T(g) are finite and related to the percolation threshold. The critical exponents associated with m and q depend on lambda for 3<lambda<5 (3<lambda<4) at the P-F (P-SG) boundary.

Journal Article↗

PubMed2005

Robustness of the avalanche dynamics in data-packet transport on scale-free networks.

We study the avalanche dynamics in the data-packet transport on scale-free networks through a simple model. In the model, each vertex is assigned a capacity proportional to the load with the proportionality constant 1+a . When the system is perturbed by a single vertex removal, the load of each vertex is redistributed, followed by subsequent failures of overloaded vertices. The avalanche size depends on the parameter a as well as which vertex triggers it. We find that there exists a critical value a(c) at which the avalanche size distribution follows a power law. The critical exponent associated with it appears to be robust as long as the degree exponent is between 2 and 3 and is close in value to that of the distribution of the diameter changes by single vertex removal.

Journal Article↗

PubMed2005

Atmospheric brown clouds: impacts on South Asian climate and hydrological cycle.

South Asian emissions of fossil fuel SO(2) and black carbon increased approximately 6-fold since 1930, resulting in large atmospheric concentrations of black carbon and other aerosols. This period also witnessed strong negative trends of surface solar radiation, surface evaporation, and summer monsoon rainfall. These changes over India were accompanied by an increase in atmospheric stability and a decrease in sea surface temperature gradients in the Northern Indian Ocean. We conducted an ensemble of coupled ocean-atmosphere simulations from 1930 to 2000 to understand the role of atmospheric brown clouds in the observed trends. The simulations adopt the aerosol radiative forcing from the Indian Ocean experiment observations and also account for global increases in greenhouse gases and sulfate aerosols. The simulated decreases in surface solar radiation, changes in surface and atmospheric temperatures over land and sea, and decreases in monsoon rainfall are similar to the observed trends. We also show that greenhouse gases and sulfates, by themselves, do not account for the magnitude or even the sign in many instances, of the observed trends. Thus, our simulations suggest that absorbing aerosols in atmospheric brown clouds may have played a major role in the observed regional climate and hydrological cycle changes and have masked as much as 50% of the surface warming due to the global increase in greenhouse gases. The simulations also raise the possibility that, if current trends in emissions continue, the subcontinent may experience a doubling of the drought frequency in the coming decades.

Journal Article↗

PubMed2005

Interaction of PLGA nanoparticles with human blood constituents.

When nanoparticles are injected into the blood for drug delivery or drug detoxification, detrimental interaction of these particles with blood constituents must be avoided. In previous studies, the adsorption of albumin immunoglobulin G, and fibrinogen from blood plasma to a model hydrophobic polymer like polystyrene was investigated as was decreasing surface hydrophobicity, which quantitatively leads to decreasing amounts of adsorbed proteins on latex particles. However, the uptake of other blood constituents, such as inorganic blood electrolytes, by particles and the dispersion/coagulation characteristics of these particles in the blood stream have not been fully studied. Most importantly, the effect s of these particles on blood coagulation and hemolysis are not well known. In the present study, the poly(lactide-co-glycolide) acid(PLGA) nanoparticles were synthesized by using nanoprecipitation. The uptake of blood electrolytes from simulated blood fluid (SBF) and the stability (dispersion/aggregation) of nanoparticles in SBF was examined by using different loading amounts of PLGA and different contact time between PLGA nanoparticles and SBF. The interaction of particles with the organic components of blood was also studied by using the measurement of red blood cell hemolysis and blood clotting with raw PLGA, surfactant modified PLGA, and PEGylated PLGA.

Blood↗

PubMed2005

Photon transitions in Upsilon(2S) and Upsilon(3S) decays.

We have studied the inclusive photon spectra in Upsilon(2S) and Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S) --> gammachi(bJ)(1P) and Upsilon(3S) --> gammachi(bJ)(2P) (J = 0, 1, 2). We measure the rate for a rare E1 transition Upsilon(3S) --> gammachi(b0)(1P) for the first time. We also set upper limits on the rates for the hindered magnetic dipole (M1) transitions to the eta(b)(1S) and eta(b)(2S) states.

Journal Article↗

PubMed2005

Observation of 1(-)0(-) final states from psi(2S) decays and e(+)e(-) annihilation.

Using CLEO data collected from CESR e(+)e(-) collisions at the psi(2S) resonance and nearby continuum at sqrt[s]=3.67 GeV, we report the first significantly nonzero measurements of light vector-pseudoscalar hadron pair production (including rhopi, omegapi, rhoeta, and K(*0)K0 ) and the pi(+)pi(-)pi(0) final state, both from psi(2S) decays and direct e(+)e(-) annihilation.

Journal Article↗

PubMed2005

Measurement of the muonic branching fractions of the narrow upsilon resonances.

The decay branching fractions of the three narrow Upsilon resonances to mu(+)mu(-) have been measured by analyzing about 4.3 fb(-1) e(+)e(-) data collected with the CLEO III detector. The branching fraction B(Upsilon(1S)-->mu(+)mu(-))=(2.49+/-0.02+/-0.07)% is consistent with the current world average, but B(Upsilon(2S)-->mu(+)mu(-))=(2.03+/-0.03+/-0.08)% and B(Upsilon(3S)-->mu(+)mu(-))=(2.39+/-0.07+/-0.10)% are significantly larger than prior results. These new muonic branching fractions imply a narrower total decay width for the Upsilon(2S) and Upsilon(3S) resonances and lower other branching fractions that rely on these decays in their determination.

Journal Article↗

PubMed2005

Transjugular intrahepatic portosystemic shunts for refractory ascites after liver transplantation.

PURPOSE: To study the efficacy of transjugular intrahepatic portosystemic shunts (TIPS) in the management of refractory ascites after liver transplantation. PATIENTS AND METHODS: Between January 1995 and December 2003, 309 primary adult liver transplants were performed. Refractory ascites was defined as active interventions (salt restriction, diuretic use, repeated paracentesis) needed beyond 30 days after transplantation. These patients were managed with TIPS placement. RESULTS: Eight TIPS were placed in 8 patients at a mean of 11.5 months after transplantation (range, 2-36 months). There were 5 males and 3 females, age 54 +/- 8.2 years. Hepatitis C was the primary diagnosis in 7 patients and primary biliary cirrhosis in 1. Indications for TIPS included refractory ascites (8), associated variceal bleeding (2), and various degrees of hepatic vein outflow stenosis (3). Seven patients had resolution of ascites and associated findings of portal hypertension, and 1 patient with persistent ascites had severe hepatic vein outflow stenosis and associated hepatitis C in the allograft. Two patients required retransplantation for recurrent hepatitis C. There were 3 deaths: liver failure (1), organ failure after retransplantation (1), and lung cancer 5 months after TIPS (1). Currently, 5 patients are alive without clinical evidence of ascites 9, 13, 15, 24, and 70 months after TIPS. CONCLUSIONS: The TIPS device can be used safely and effectively to control refractory ascites after liver transplantation. In the setting of organ dysfunction, these patients should be considered sooner for retransplantation.

Adult↗

PubMed2005

Day-long subcutaneous infusion of exenatide lowers glycemia in patients with type 2 diabetes.

Exenatide (exendin-4) is an incretin mimetic with potential antidiabetic activity. This study examined the effects of a continuous subcutaneous (SC) infusion of exenatide (0.2, 0.4, 0.6, or 0.8 microg/kg/day) or placebo (PBO) on glycemic control over 23 h intervals. Twelve subjects with type 2 diabetes treated with metformin and/or diet received 10 infusions (4 exenatide, 6 PBO) on consecutive days. Exenatide was given in a dose-increasing design with at least one placebo infusion between each exenatide infusion, and with meals and a snack provided during the first 14 h of infusion. Plasma exenatide concentrations were dose-proportional. Plasma glucose (4-23 h) was lower in all exenatide arms compared to placebo (p<0.0001). The change in insulin/glucagon ratio and amylin concentrations from pre-infusion to post-infusion was increased (p<0.005, p<0.05, respectively) in the combined exenatide arms, but remained unchanged in the placebo groups. Nausea and vomiting were the most common treatment emergent adverse events. Exenatide infusion also appeared to have positive effects on beta-cell and alpha-cell function as measured by proinsulin/insulin ratios and mean glucagon concentrations. In summary, exenatide lowered plasma glucose during both prandial and fasting states when delivered as a continuous SC infusion over twenty-three hours, suggesting that exenatide can provide day-long glycemic control in patients with type 2 diabetes.

Adult↗

PubMed2005

Variations in the behaviors to novel objects among five inbred strains of mice.

Novelty stimuli cause various behavioral responses, such as exploration and avoidance, and contextual variables may contribute to the behavioral outputs. Here, we tried to compare the behavioral responses to novel objects of five inbred strains of mice (C57BL/6J, 129/svJae, C3H/HeJ, BALB/cJ and DBA/2J) by using a modified novel object test where a small light-weight cube wrapped with paper was presented to mice in a home cage without beddings. In response to these objects, the C57BL/6J, 129/svJae and C3H/HeJ mice showed mild exploratory behaviors, such as approaching, sniffing or brief contact. In striking contrast, the BALB/cJ and DBA/2J mice, which have been known to show high avoidance/low exploration in other behavioral paradigms, exhibited play-like secondary reactions toward the objects after initial primary exploratory behaviors. Specifically, DBA/2J mice would move the object around in the cage, holding it with their mouths, and BALB/cJ mice would gnaw the object, eventually stripping off the wrapping paper. Such behaviors decreased when similar objects were presented repeatedly. The present results suggest that active manipulations of novel objects may be a relevant parameter for measuring novelty-induced behaviors in mice and appear to be strongly influenced by genetic factors.

Animals↗

PubMed2004

Search for the lepton-flavor-violating leptonic B(0)-->mu(+/-)tau(-/+) and B(0)-->e(+/-)tau(-/+).

We have searched a sample of 9.6 x 10(6) BB events for the lepton-flavor-violating leptonic B decays, B(0)-->mu(+/-)tau(-/+) and B(0)-->e(+/-)tau(-/+). The tau lepton was detected through the decay modes tau-->lnunu(-) , where l=e, mu. There is no indication of a signal, and we obtain the 90% confidence level upper limits B(B(0)-->mu(+/-)tau(-/+))<3.8 x 10(-5) and B(B(0)-->e(+/-)tau(-/+))<1.3 x 10(-4).

Journal Article↗

PubMed2004

Steady-state solutions of hydrodynamic traffic models.

We investigate steady-state solutions of hydrodynamic traffic models in the absence of any intrinsic inhomogeneity on roads such as on-ramps. It is shown that typical hydrodynamic models possess seven different types of inhomogeneous steady-state solutions. The seven solutions include those that have been reported previously only for microscopic models. The characteristic properties of wide jam such as moving velocity of its spatiotemporal pattern and/or out-flux from wide jam are shown to be uniquely determined and thus independent of initial conditions of dynamic evolution. Topological considerations suggest that all of the solutions should be common to a wide class of traffic models. The results are discussed in connection with the universality conjecture for traffic models. Also the prevalence of the limit-cycle solution in a recent study of a microscopic model is explained in this approach.

Journal Article↗

PubMed2004

Hydrophilized poly(lactide-co-glycolide) nanospheres with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer.

A novel method for preparing the PLGA nanospheres with hydrophilic surface has been designed and characterized. Because of good solubility of tetraglycol in water, PLGA (poly(lactide-co-glycolide)) nanospheres were formed by spraying the PLGA/tetraglycol solution into water. The size of PLGA nanospheres was manipulated by changing the concentration of PLGA/tetraglycol solution. Based on the hydrophobic interaction between PLGA and poly(propylene oxide) domain of F-127 (one of Pluronics, poly(ethylene oxide)-poly(propylene oxide)poly(ethylene oxide) triblock copolymer, F-127-coated PLGA nanospheres was prepared to enhance the stability of PLGA nanospheres in the aqueous media. For the application as a drug delivery vehicle, it was characterized by measuring the loading amount, the encapsulation efficiency and the release pattern of drug. Paclitaxel used as a potent anti-cancer drug was selected as a model drug.

Antineoplastic Agents↗

PubMed2004

Bacillus anthracis contamination and inhalational anthrax in a mail processing and distribution center.

AIMS: Four inhalational anthrax cases occurred in a large mail processing and distribution center in Washington, DC, after envelopes containing Bacillus anthracis spores were processed. This report describes the results of sampling for B. anthracis spores during investigations conducted in October and December 2001. METHODS AND RESULTS: Wet swabs, wet wipes, vacuum sock, and air-filter samples were collected throughout the facility to characterize the extent of building contamination. The results showed widespread contamination of B. anthracis spores, particularly associated with one delivery bar code sorter (DBCS) machine that had sorted the spore-containing envelopes and an area where the envelopes were handled by postal workers. Spore concentrations decreased as distance from the DBCS machine increased, but spores were widely dispersed into surrounding areas. CONCLUSION: The spatial distribution of culture positive samples was closely related to the work areas of the inhalational anthrax cases and supported epidemiological evidence that the workers became ill from exposure to B. anthracis spores in areas where the contaminated envelopes had travelled. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this investigation were used to guide decontamination efforts and provided baseline spore concentrations for follow-up measurements after the building had been cleaned. Implementing methods to reduce aerosolization and dispersion of dust within the facility would reduce postal workers' potential exposures to bioterrorism agents.

Air Pollution, Indoor↗

PubMed2004

Mapping of the prostate in endorectal coil-based MRI/MRSI and CT: a deformable registration and validation study.

The endorectal coil is being increasingly used in magnetic resonance imaging (MRI) and MR spectroscopic imaging (MRSI) to obtain anatomic and metabolic images of the prostate with high signal-to-noise ratio (SNR). In practice, however, the use of endorectal probe inevitably distorts the prostate and other soft tissue organs, making the analysis and the use of the acquired image data in treatment planning difficult. The purpose of this work is to develop a deformable image registration algorithm to map the MRI/MRSI information obtained using an endorectal probe onto CT images and to verify the accuracy of the registration by phantom and patient studies. A mapping procedure involved using a thin plate spline (TPS) transformation was implemented to establish voxel-to-voxel correspondence between a reference image and a floating image with deformation. An elastic phantom with a number of implanted fiducial markers was designed for the validation of the quality of the registration. Radiographic images of the phantom were obtained before and after a series of intentionally introduced distortions. After mapping the distorted phantom to the original one, the displacements of the implanted markers were measured with respect to their ideal positions and the mean error was calculated. In patient studies, CT images of three prostate patients were acquired, followed by 3 Tesla (3 T) MR images with a rigid endorectal coil. Registration quality was estimated by the centroid position displacement and image coincidence index (CI). Phantom and patient studies show that TPS-based registration has achieved significantly higher accuracy than the previously reported method based on a rigid-body transformation and scaling. The technique should be useful to map the MR spectroscopic dataset acquired with ER probe onto the treatment planning CT dataset to guide radiotherapy planning.

Algorithms↗

PubMed2004

Detection of laryngeal carcinoma and epithelial hyperplastic laryngeal lesions via a rapid-access dysphonia clinic.

Recent government initiatives in the UK have focused on streamlining oncology services by reducing waiting times between urgent referral, assessment and treatment of patients with possible cancer. The performance of the Quick Early Diagnosis Dysphonia Clinic of the Queen Elizabeth Hospital, Birmingham, between May 1997 and April 2001 was reviewed. Of 721 patients reviewed, 123 (17 per cent) had clinically suspicious laryngeal lesions. Thirteen cases of epithelial hyperplastic laryngeal lesions and 27 laryngeal malignancies were diagnosed. There was no statistical link between early cancer detection and assessment within two weeks of referral. However, rapid-access clinics for dysphonia serve an important role in the reassurance and multidisciplinary management of patients with persistent hoarseness. Greater financial commitments are necessary to achieve compliance with objectives for a maximum two-week wait for patients with suspected laryngeal malignancy.

Female↗

PubMed2003

Sandpile on scale-free networks.

We investigate the avalanche dynamics of the Bak-Tang-Wiesenfeld sandpile model on scale-free (SF) networks, where the threshold height of each node is distributed heterogeneously, given as its own degree. We find that the avalanche size distribution follows a power law with an exponent tau. Applying the theory of the multiplicative branching process, we obtain the exponent tau and the dynamic exponent z as a function of the degree exponent gamma of SF networks as tau=gamma divided by (gamma-1) and z=(gamma-1) divided by (gamma-2) in the range 2 3, with a logarithmic correction at gamma=3. The analytic solution supports our numerical simulation results. We also consider the case of a uniform threshold, finding that the two exponents reduce to the mean-field ones.

Journal Article↗