Critical issues in breast imaging by vibro-acoustography

Clinically, there are two important issues in breast imaging: detection of microcalcifications and identification of mass lesions. X-ray mammography is the main imaging method used for detection of microcalcification, and ultrasound imaging is normally used for detection of mass lesions in breast. Both these methods have limitations that reduce their clinical usefulness. For this reasons, alternative breast imaging modalities are being sought. vibro-acoustography is an imaging modality that has emerged in recent years. This method is based on low-frequency harmonic vibrations induced in the object by the radiation force of ultrasound. This paper describes potential applications of vibro-acoustography for breast imaging and addresses the critical imaging issues such as detection of microcalcifications and mass lesions in breast. Recently, we have developed a vibro-acoustography system for in vivo breast imaging and have tested it on a number of volunteers. Resulting images show soft tissue structures and calcifications within breast with high contrast, high resolution, and no speckles. The results have been verified using X-ray mammography. The encouraging results from in vitro and in vivo experiments suggest that further development of vibro-acoustography technology may lead to a new clinical tool that can be used to detect microcalcifications as well as mass lesions in breast.     

Vibro-acoustography and multifrequency image compounding

Vibro-acoustography is an ultrasound based imaging modality that can visualize normal and abnormal soft tissue through mapping the acoustic response of the object to a harmonic radiation force at frequency Δf induced by focused ultrasound. In this method, the ultrasound energy is converted from high ultrasound frequencies to a low acoustic frequency (acoustic emission) that is often two orders of magnitude smaller than the ultrasound frequency. The acoustic emission is normally detected by a hydrophone. Depending on the setup, this low frequency sound may reverberate by object boundaries or other structures present in the acoustic paths before it reaches the hydrophone. This effect produces an artifact in the image in the form of gradual variations in image intensity that may compromise image quality. The use of tonebursts with finite length yields acoustic emission at Δf and at sidebands centered about Δf. Multiple images are formed by selectively applying bandpass filters on the acoustic emission at Δf and the associated sidebands. The data at these multiple frequencies are compounded through both coherent and incoherent processes to reduce the acoustic emission reverberation artifacts. Experimental results from a urethane breast phantom are described. The coherent and incoherent compounding of multifrequency data show, both qualitatively and quantitatively, the efficacy of this reverberation reduction method. This paper presents theory describing the physical origin of this artifact and use of image data created using multifrequency vibro-acoustography for reducing reverberation artifacts.     

A complete convergence theorem for stationary regularly varying multivariate time series

For a class of stationary regularly varying and weakly dependent multivariate time series (X _n ), we prove the so-called complete convergence result for the space–time point processes of the form \(N_{n} = \sum _{i=1}^{n} \delta _{(i/n, \boldsymbol {X}_{i}/a_{n})}.\) As an application of our main theorem, we give a simple proof of the invariance principle for the corresponding partial maximum process.     

Anti-Inflammatory Effect of Phytoncide in an Animal Model of Gastrointestinal Inflammation

Background: Phytoncide is known to have antimicrobial and anti-inflammatory properties. Purpose: This study was carried out to confirm the anti-inflammatory activity of two types of phytoncide extracts from pinecone waste. Methods: We made two types of animal models to evaluate the efficacy, an indomethacin-induced gastroenteritis rat model and a dextran sulfate sodium-induced colitis mouse model. Result: In the gastroenteritis experiment, the expression of induced-nitric oxide synthase (iNOS), a marker for inflammation, decreased in the phytoncide-supplemented groups, and gastric ulcer development was significantly inhibited (p < 0.05). In the colitis experiment, the shortening of the colon length and the iNOS expression were significantly suppressed in the phytoncide-supplemented group (p < 0.05). Conclusions: Through this study, we confirmed that phytoncide can directly inhibit inflammation in digestive organs. Although further research is needed, we conclude that phytoncide has potential anti-inflammatory properties in the digestive tract and can be developed as a functional agent.     

Molecular above-threshold ionization with a circularly polarized laser field

Molecular above-threshold ionization by a circularly polarized laser field is investigated. Our theoretical approach is based on the modified molecular strong-field approximation. Various gauge-dependent versions of this approximation are considered and homonuclear and heteronuclear molecular species characterized by different symmetries are used as targets. As in the case of a linearly polarized field, the imprint of the molecular multicenter structure can be observed in the above-threshold ionization spectra. It manifests itself as minima in the rate of the ionized electrons as a function of their energy. The locations of these minima are strongly influenced by the symmetry of the corresponding highest occupied molecular orbital as well as the internuclear separation. Analyzing the interference structures of the electron spectra one can obtain information about the molecular symmetry.     

Spectroscopic studies of dactinomycin and vinorelbine binding to deoxyribonucleic acid and chromatin

Dactinomycin and vinorelbine are anticancer drugs, widely used as chemotherapeutic agents for the treatment of various cancers. This study represents an attempt to compare the effect of these drugs on DNA and soluble chromatin employing UV/vis, fluorescence and circular dichroism spectroscopy techniques. The results demonstrated that the absorbance at 260 and 210 nm was decreased and quenching of drugs with DNA and chromatin chromospheres induced reduction of fluorescence emission intensity. Circular dichroism profiles showed that the binding of drugs induced structural changes in both positive and negative extremes of DNA and chromatin revealing release or displacement of histone proteins from chromatin upon dactinomycin binding whereas vinorelbine preceded the chromatin into compaction. The results suggest that dactinomycin shows higher affinity to DNA compared to chromatin, whereas, vinorelbine recognizes the chromatin structure with higher affinity than free DNA. Also chromatin proteins play a fundamental role in drug-chromatin complex process.     

Flavonoid-DNA binding studies and thermodynamic parameters

Interactional studies of new flavonoid derivatives (Fl) with chicken blood ds.DNA were investigated spectrophotometrically in DMSO-H2O (9:1 v/v) at various temperatures. Spectral parameters suggest considerable binding between the flavonoid derivatives studied and ds.DNA. The binding constant values lie in the enhanced-binding range. Thermodynamic parameters obtained from UV studies also point to strong spontaneous binding of Fl with ds.DNA. Viscometric studies complimented the UV results where a small linear increase in relative viscosity of the DNA solution was observed with added optimal flavonoid concentration. An overall mixed mode of interaction (intercalative plus groove binding) is proposed between DNA and flavonoids. Conclusively, investigated flavonoid derivatives are found to be strong DNA binders and seem to be promising drug candidates like their natural analogues.     

Quantifying the electronic effects of carbohydrate hydroxy groups by using aminosugar models

Methyl amino-deoxy-glycosides with α- and β-gluco, α-galacto, or α-manno stereochemistry with the amino functionality in each of the four possible non-anomeric positions have been synthesized and their pK(a) values determined by titration. These model compounds were chosen because they are the amino derivatives of the most common glycosyl acceptors. From this study it was possible to evaluate the electron density at each of the given positions in the carbohydrate and compare them. Some general trends were observed: The basicity of the amino groups decreases in the order 6-NH(2)>3-NH(2)>2-NH(2)>4-NH(2) (referring to the position). The basicity of a of an amino-deoxy-sugar generally increases when one or more substituents on the sugar ring are axial. The basicity decreases when the amine is antiperiplanar to an oxygen atom. These findings are in agreement with the observations obtained from glycosylation chemistry and the regioselective protection of sugars.     

An integrated thermal model of hot rolling

During the heavy plate rolling process, different production steps, i.e., roll passes, descaling passes, and air cooling periods, influence the temperature evolution of the plate. All these relevant aspects are covered by a one-dimensional thermal model proposed in this paper. Experiments were conducted in a rolling mill under realistic rolling conditions to parametrise and validate the model. Using pyrometer measurements, a simple model adaption strategy is developed, which can cope with uncertainties in the initial temperature profile. The model provides accurate predictions of the temperature evolution of the plate during the whole rolling process from the plate’s exit of the furnace to the last pass. Thus, it can be used for scheduling the production process. Based on the model, an observer can be designed.     

Inversion-Based Feedforward Control for the Transient Shaping of a Piezo-Actuated Cantilevered Kirchhoff Plate

Nowadays piezoelectric actuators are successfully applied for vibration suppression in structural mechanics. The progress in material and actuator development allows to put focus also on novel applications. In this contribution, a systematic approach for inversion–based feedforward control and motion planning is presented for the realization of a transient deflection profile of a cantilevered piezo–actuated plate modeling an adaptive wing. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)