Two-dimensional propagation of magnetocardiac T wave signals for characterizing myocardial ischemia
C. C. Wu, H. C. Huang, Y. B. Liu, L. C. Lin, L. Y. Lin et al.
Instead of detecting electrical signals for diagnosing cardiac abnormalities, a promising alternative is to detect the magnetic signals generated from cardiac electrical currents. The system utilizing 64 low-transition-temperature superconducting quantum interference devices was tested to detect the ... [Appl. Phys. Lett. 92, 194104 (2008)] published Thu May 15, 2008.
During vertebrate development, arteries exert a morphological control over the venous pattern through physical factors
Alia Al-Kilani, Sylvie Lorthois, Thi-Hanh Nguyen, Ferdinand Le Noble, Annemiek Cornelissen et al.
The adult vasculature is comprised of three distinct compartments: the arteries, which carry blood away from the heart and display a divergent flow pattern; the capillaries, where oxygen and nutrient delivery from blood to tissues, as well as metabolic waste removal, occurs; and the veins, which car ... [Phys. Rev. E 77, 051912 (2008)] published Thu May 15, 2008.
Two scale generalized model of polypeptide chains
A. V. Badasyan, Sh. A. Tonoyan, A. V. Tsarukyan, Y. Sh. Mamasakhlisov, A. S. Benight et al.
The generalized model of polypeptide chains (GMPC) is expanded to simultaneously consider two types of interactions occurring over different scales. This new two scale GMPC is applied in several specific cases to examine: The combined influence of stacking or antistacking and hydrogen bonding, or sp ... [J. Chem. Phys. 128, 195101 (2008)] published Thu May 15, 2008.
Two scale generalized model of polypeptide chains
A. V. Badasyan, Sh. A. Tonoyan, A. V. Tsarukyan, Y. Sh. Mamasakhlisov, A. S. Benight et al.
The generalized model of polypeptide chains (GMPC) is expanded to simultaneously consider two types of interactions occurring over different scales. This new two scale GMPC is applied in several specific cases to examine: The combined influence of stacking or antistacking and hydrogen bonding, or sp ... [J. Chem. Phys. 128, 195101 (2008)] published Thu May 15, 2008.
Determination of time-course change rate for arterial xenon using the time course of tissue xenon concentration in xenon-enhanced computed tomography
Shigeru Sase, Hideaki Takahashi, Hiroki Ikeda, Minoru Kobayashi, Nobuyuki Matsumoto et al.
In calculating tissue blood flow (TBF) according to the Fick principle, time-course information on arterial tracer concentration is indispensable and has a considerable influence on the accuracy of calculated TBF. In TBF measurement by xenon-enhanced computed tomography (Xe-CT), nonradioactive xenon ... [Med. Phys. 35, 2331 (2008)] published Thu May 15, 2008.
Semiautomated three-dimensional segmentation software to quantify carpal bone volume changes on wrist CT scans for arthritis assessment
J. Duryea, M. Magalnick, S. Alli, L. Yao, M. Wilson et al.
Rapid progression of joint destruction is an indication of poor prognosis in patients with rheumatoid arthritis. Computed tomography (CT) has the potential to serve as a gold standard for joint imaging since it provides high resolution three-dimensional (3D) images of bone structure. The authors hav ... [Med. Phys. 35, 2321 (2008)] published Thu May 15, 2008.
Dynamic speckle algorithms comparison using receiver operating characteristic
Christian C. Oritz, Gonzalo H. Sendra, Hector Rabal, Ricardo Arizaga, and Marcelo Trivi
Dynamic speckle is a useful technique to show biological tissue activity and evolving processes in industry. There are several algorithms for quantitative and qualitative characterization of dynamic speckle. We use the statistical method receiver operating characteristic (ROC) to compare some speckl ... [Opt. Eng. 47, 057005 (2008)] published Thu May 15, 2008.
Cholesterol Perturbs Lipid Bilayers Nonuniversally
Jianjun Pan, Thalia T. Mills, Stephanie Tristram-Nagle, and John F. Nagle
Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K, the thickness D, and the orientational order parameter S of lipid bilayers. We find that the effects are differen ... [Phys. Rev. Lett. 100, 198103 (2008)] published Thu May 15, 2008.
Radial Distribution of RNA Genomes Packaged inside Spherical Viruses
Se Il Lee and Toan T. Nguyen
The problem of RNA genomes packaged inside spherical viruses is studied. The RNA-capsid attraction is assumed to be nonspecific and occurs at the inner capsid surface only. For weak attraction, RNA concentration is maximum at the center of the capsid to maximize their configurational entropy. For st ... [Phys. Rev. Lett. 100, 198102 (2008)] published Thu May 15, 2008.
Properties of contact matrices induced by pairwise interactions in proteins
Sanzo Miyazawa and Akira R. Kinjo
The properties of contact matrices (C matrices) needed for native proteins to be the lowest-energy conformations are considered in relation to a contact energy matrix (E matrix). The total conformational energy is assumed to consist of pairwise interaction energies between atoms or residues, each of ... [Phys. Rev. E 77, 051910 (2008)] published Wed May 14, 2008.
Deterministic excitable media under Poisson drive: Power law responses, spiral waves, and dynamic range
Tiago L. Ribeiro and Mauro Copelli
When each site of a spatially extended excitable medium is independently driven by a Poisson stimulus with rate h, the interplay between creation and annihilation of excitable waves leads to an average activity F. It has recently been suggested that in the low-stimulus regime (h~0) the response func ... [Phys. Rev. E 77, 051911 (2008)] published Wed May 14, 2008.
Surface-directed differentiation of embryonic stem cells
E. Hanley, J. L. Lauer, B. K. Micales, G. E. Lyons, and J. L. Shohet
Here, we explore how embryonic stem-cell (ESC) differentiation patterns on surfaces are affected by changes in the processing parameters of plasma-polymerized materials. Mouse ESCs were plated on plasma-polymerized tetraethylene glycol dimethyl ether (tetraglyme) surfaces on glass. Depending on the ... [Appl. Phys. Lett. 92, 193902 (2008)] published Wed May 14, 2008.
Photoacoustic probing of fluorophore excited state lifetime with application to oxygen sensing
Shai Ashkenazi, Shen-Wen Huang, Thomas Horvath, Yong-Eun L. Koo, and Raoul Kopelman
A new method is developed to perform local measurements of fluorophore excited state lifetimes in turbid media without collecting the fluorescence emission. The method is based on a pump-probe approach where a first laser pulse excites the dye and then a second laser pulse is used for photoacoustic ... [J. Biomed. Opt. 13, 034023 (2008)] published Wed May 14, 2008.
Dosimetric characterization of CyberKnife radiosurgical photon beams using polymer gels
E. Pantelis, C. Antypas, L. Petrokokkinos, P. Karaiskos, P. Papagiannis et al.
Dose distributions registered in water equivalent, polymer gel dosimeters were used to measure the output factors and off-axis profiles of the radiosurgical photon beams employed for CyberKnife radiosurgery. Corresponding measurements were also performed using a shielded silicon diode commonly emplo ... [Med. Phys. 35, 2312 (2008)] published Wed May 14, 2008.
Radiochromic film dosimetry: Reflection vs transmission scanning
J. Kalef-Ezra and K. Karava
The objective of this study was to compare the transmission and the reflection scanning reading modes of radiochromic MD-55 films of a document scanner. The use of the red channel of the red-green-blue images results in measurement accuracy that did not differ between the two reading modes. On the o ... [Med. Phys. 35, 2308 (2008)] published Wed May 14, 2008.
An analysis of tolerance levels in IMRT quality assurance procedures
Parminder S. Basran and Milton K. Woo
Increased use of intensity modulated radiation therapy (IMRT) has resulted in increased efforts in patient quality assurance (QA). Software and detector systems intended to streamline the IMRT quality assurance process often report metrics, such as percent discrepancies between measured and computed ... [Med. Phys. 35, 2300 (2008)] published Wed May 14, 2008.
Single-sweep methods for free energy calculations
Luca Maragliano and Eric Vanden-Eijnden
A simple, efficient, and accurate method is proposed to map multidimensional free energy landscapes. The method combines the temperature-accelerated molecular dynamics (TAMD) proposed in [L. Maragliano and E. Vanden-Eijnden, Chem. Phys. Lett. 426, 168 (2006)] with a variational reconstruction method ... [J. Chem. Phys. 128, 184110 (2008)] published Wed May 14, 2008.
Conformational study of jet-cooled L-phenylglycine
Hyung Min Kim, Kyu Young Han, Juyeon Park, Seong Keun Kim, and Zee Hwan Kim
We investigated the conformational structures of L-phenylglycine in the gas phase by photoionization and double resonance spectroscopy techniques as well as high-level ab initio calculations. The UV-UV and IR-UV double resonance spectroscopy suggested that there exists only one conformer that has a ... [J. Chem. Phys. 128, 184313 (2008)] published Wed May 14, 2008.
Ion thermalization using pressure transients in a quadrupole ion trap coupled to a vacuum matrix-assisted laser desorption ionization source and a reflectron time-of-flight mass analyzer
D. Papanastasiou, O. Belgacem, M. Sudakov, and E. Raptakis
Efficient trapping and detection of intact peptide ions is demonstrated in a quadrupole ion trap (QIT) coupled to an external vacuum matrix-assisted laser desorption ionization (MALDI) source. Deactivation of metastable ions generated by MALDI is achieved in a pressure transient environment inside t ... [Rev. Sci. Instrum. 79, 055103 (2008)] published Wed May 14, 2008.
Kinematic Analysis and Optimization of a Novel Robot for Surgical Tool Manipulation
Xiaoli Zhang and Carl A. Nelson
The size and limited dexterity of current surgical robotic systems are factors that limit their usefulness. To improve the level of assimilation of surgical robots in minimally invasive surgery (MIS), a compact, lightweight surgical robotic positioning mechanism with four degrees of freedom (DOFs) ( ... [J. Med. Devices 2, 021003 (2008)] published Wed May 14, 2008.
Role of Secondary Low-Energy Electrons in the Concomitant Chemoradiation Therapy of Cancer
Yi Zheng, Darel J. Hunting, Patrick Ayotte, and Leon Sanche
Solid films of DNA with and without the chemotherapeutic agent cisplatin bonded to guanine were bombarded with electrons of 1, 10, 100, and 60 000 eV causing single and double strand breaks. In the presence of cisplatin this damage was increased by factors varying from 1.3 to 4.4 owing to an increas ... [Phys. Rev. Lett. 100, 198101 (2008)] published Wed May 14, 2008.
Ordering and lyotropic behavior of a silicon-supported cationic and neutral lipid system studied by neutron reflectivity
F. Domenici, C. Castellano, A. Congiu, G. Pompeo, and R. Felici
Self-assembling of amphipathic lipid films on solid support allows the structural investigation of important biological model systems, such as the vectorlike lipid membranes, in order to improve DNA transfection in nonviral gene therapy. We present a neutron reflectivity study of a binary lipid syst ... [Appl. Phys. Lett. 92, 193901 (2008)] published Tue May 13, 2008.
Reducing monitor units for robotic radiosurgery by optimized use of multiple collimators
Johan J. Poll, Mischa S. Hoogeman, Jean-Briac Prevost, Joost J. Nuyttens, Peter C. Levendag et al.
Advances in image guidance and dose delivery techniques, and increased use of hypofractionation, have led to prolonged radiotherapy fraction duration. This is also the case with robotic radiosurgery, as extensive on-line image guidance procedures, many beams, and usually high fraction doses are used ... [Med. Phys. 35, 2294 (2008)] published Tue May 13, 2008.
Energy spectrum based calculation of the half and the tenth value layers for brachytherapy sources using a semiempirical parametrized mass attenuation coefficient formulism
Ning J. Yue
As different types of radionuclides (e.g., Cs source) are introduced for clinical use in brachytherapy, the question is raised regarding whether a relatively simple method exists for the derivation of values of the half value layer (HVL) or the tenth value layer (TVL). For the radionuclide that has ... [Med. Phys. 35, 2286 (2008)] published Tue May 13, 2008.
Mode excitation Monte Carlo simulations of mesoscopically large membranes
Oded Farago
Solvent-free coarse grained models represent one of the most promising approaches for molecular simulations of mesoscopically large membranes. In these models, the size of the simulated membrane is limited by the slow relaxation time of the longest bending mode. Here, we present a Monte Carlo algori ... [J. Chem. Phys. 128, 184105 (2008)] published Tue May 13, 2008.
Molecular motion in cell membranes: Analytic study of fence-hindered random walks
V. M. Kenkre, L. Giuggioli, and Z. Kalay
A theoretical calculation is presented to describe the confined motion of transmembrane molecules in cell membranes. The study is analytic, based on Master equations for the probability of the molecules moving as random walkers, and leads to explicit usable solutions including expressions for the mo ... [Phys. Rev. E 77, 051907 (2008)] published Tue May 13, 2008.
Dryland ecosystems: The coupled stochastic dynamics of soil water and vegetation and the role of rainfall seasonality
R. Vezzoli, C. De Michele, H. Pavlopoulos, and R. J. Scholes
In drylands the soil water availability is a key factor ruling the architecture of the ecosystem. The soil water reflects the exchanges of water among soil, vegetation, and atmosphere. Here, a dryland ecosystem is investigated through the analysis of the local interactions between soil water and veg ... [Phys. Rev. E 77, 051908 (2008)] published Tue May 13, 2008.
Interplay between a phase response curve and spike-timing-dependent plasticity leading to wireless clustering
Hideyuki Cateau, Katsunori Kitano, and Tomoki Fukai
A phase response curve (PRC) characterizes the signal transduction between oscillators such as neurons on a fixed network in a minimal manner, while spike-timing-dependent plasiticity (STDP) characterizes the way of rewiring networks in an activity-dependent manner. This paper demonstrates that thes ... [Phys. Rev. E 77, 051909 (2008)] published Tue May 13, 2008.
Traffic of single-headed motor proteins KIF1A: Effects of lane changing
Debashish Chowdhury, Ashok Garai, and Jian-Sheng Wang
KIF1A kinesins are single-headed motor proteins which move on cylindrical nanotubes called microtubules (MTs). A normal MT consists of 13 protofilaments on which the equispaced motor binding sites form a periodic array. The collective movement of the kinesins on a MT is, therefore, analogous to vehi ... [Phys. Rev. E 77, 050902 (2008)] published Mon May 12, 2008.
Optimization of deterministic transport parameters for the calculation of the dose distribution around a high dose-rate [sup 192]Ir brachytherapy source
Kent A. Gifford, Michael J. Price, John L. Horton, Jr., Todd A. Wareing, and Firas Mourtada
The goal of this work was to calculate the dose distribution around a high dose-rate Ir brachytherapy source using a multi-group discrete ordinates code and then to compare the results with a Monte Carlo calculated dose distribution. The unstructured tetrahedral mesh discrete ordinates code Attila v ... [Med. Phys. 35, 2279 (2008)] published Mon May 12, 2008.
c-erbB-2 sensing using AlGaN/GaN high electron mobility transistors for breast cancer detection
K. H. Chen, B. S. Kang, H. T. Wang, T. P. Lele, F. Ren et al.
Antibody-functionalized, Au-gated AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect c-erbB-2, which is a breast cancer marker. The antibody was anchored to the gate area through immobilized thioglycolic acid. The AlGaN/GaN HEMT drain-source current showed a rapid response of l ... [Appl. Phys. Lett. 92, 192103 (2008)] published Mon May 12, 2008.
On HIV Prevalence and AIDS Deaths in India
B. D. Aggarwala
The National AIDS Control Organization (NACO) of India had estimated, before this year, that there were 5.134 million HIV positive people in India at the end of 2004 and that they were increasing at the rate of more than a quarter of a million people every year. In a recent publication, we estimated ... [AIP Conf. Proc. 1007, 235 (2008)] published Mon May 12, 2008.
Constructing Linkage Disequilibrium Map with Iterative Approach
S. I. Ao
With recent advance of the genotyping single nucleotide polymorphisms (SNPs) in mass scale of high density in a candidate region of the human genome, the linkage disequilibrium analysis can offer a much higher resolution of the biological samples than the traditional linkage maps. We have formulated ... [AIP Conf. Proc. 1007, 1 (2008)] published Mon May 12, 2008.
Biopsy needle tips with markers---MR compatible needles for high-precision needle tip positioning
Bernd M. Muller-Bierl, Petros Martirosian, Hansjorg Graf, Andreas Boss, Claudius Konig et al.
Needle tip visualization is of high importance in magnetic resonance imaging (MRI) guided interventional procedures, for example for taking biopsies from suspicious lesions in the liver or kidney. The exact position of the needle tip is often obscured by image artifacts arising from the magnetic pro ... [Med. Phys. 35, 2273 (2008)] published Fri May 9, 2008.
Comments on shielding for dual energy accelerators
M. C. Rossi, H. M. Lincoln, D. J. Quarin, and R. D. Zwicker
Determination of shielding requirements for medical linear accelerators has been greatly facilitated by the publication of the National Council on Radiation Protection and Measurements (NCRP) latest guidelines on this subject in NCRP Report No. 151. In the present report the authors review their own ... [Med. Phys. 35, 2267 (2008)] published Fri May 9, 2008.
Attractive membrane domains control lateral diffusion
Martin B. Forstner, Douglas S. Martin, Florian Ruckerl, Josef A. Kas, and Carsten Selle
Lipid membranes play a fundamental role in vital cellular functions such as signal transduction. Many of these processes rely on lateral diffusion within the membrane, generally a complex fluid containing ordered microdomains. However, little attention has been paid to the alterations in transport d ... [Phys. Rev. E 77, 051906 (2008)] published Fri May 9, 2008.
An Ultrasound Probe Holder for Image-Guided Surgery
Basem Fayez Yousef, Rajni V. Patel, and Mehrdad Moallem
Automating image-guided therapy and registering a medical image to a patient require knowledge of the locations of both the medical image source (e.g., ultrasound) and the surgical tool with respect to a global coordinate system that is known relative to the patient. Also, sturdiness of the medical ... [J. Med. Devices 2, 021002 (2008)] published Fri May 9, 2008.
Respiratory System Model for Quasistatic Pulmonary Pressure-Volume (P-V) Curve: Inflation-Deflation Loop Analyses
R. Amini and U. Narusawa
A respiratory system model (RSM) is developed for the deflation process of a quasistatic pressure-volume (P-V) curve, following the model for the inflation process reported earlier. In the RSM of both the inflation and the deflation limb, a respiratory system consists of a large population of basic ... [J. Biomech. Eng. 130, 031020 (2008)] published Fri May 9, 2008.
Characterizing the Diversity of Dynamics in Complex Networks Without Border Effects. (arXiv:0805.2298v1 [q-bio.TO])
ePrint arXiv http://arXiv.org/
A comparative evolutionary study of transcription networks. (arXiv:0805.2288v1 [q-bio.MN])
ePrint arXiv http://arXiv.org/
DNA duplex cage structures with icosahedral symmetry. (arXiv:0711.4344v2 [q-bio.BM] UPDATED)
ePrint arXiv http://arXiv.org/
How T-cells use large deviations to recognize foreign antigens. (arXiv:q-bio/0605016v2 [q-bio.SC] UPDATED)
ePrint arXiv http://arXiv.org/
To what extent does genealogical ancestry imply genetic ancestry?. (arXiv:0805.0634v2 [q-bio.PE] UPDATED)
ePrint arXiv http://arXiv.org/
Maximally Informative Stimuli and Tuning Curves for Sigmoidal Rate-Coding Neurons and Populations. (arXiv:0802.1570v2 [q-bio.NC] UPDATED)
ePrint arXiv http://arXiv.org/