Discrete Windows Research Articles

Discrete-time windows with minimal RMS bandwidth for given RMS temporal width

We derive a family of discrete window functions for the N-point Fourier transform for application in spectral analysis that optimize the root mean square (RMS) frequency width σω for a given temporal RMS width σt. The window family yields as a byproduct the minimum time-bandwidth product σωσt for given σt and N. The new windows interpolate for decreasing σt between the popular Cosine-window and a nearly Gaussian window. The new “confined Gaussian” window function gk(cG) (with k=0,…,N−1) is extremely well approximated by gk(acG)∝G(k)−G(−1/2)[G(k+N)+G(k−N)]/[G(−1/2+N)+G(−1/2−N)] with the Gaussian G(x)=exp[−δt2(x−(N−1)/2)2/(4s2)], the temporal width s≈σt, and time step δt.

Temporal Windows in Visual Processing: “Prestimulus Brain State” and “Poststimulus Phase Reset” Segregate Visual Transients on Different Temporal Scales

Dynamic vision requires both stability of the current perceptual representation and sensitivity to the accumulation of sensory evidence over time. Here we study the electrophysiological signatures of this intricate balance between temporal segregation and integration in vision. Within a forward masking paradigm with short and long stimulus onset asynchronies (SOA), we manipulated the temporal overlap of the visual persistence of two successive transients. Human observers enumerated the items presented in the second target display as a measure of the informational capacity read-out from this partly temporally integrated visual percept. We observed higher β-power immediately before mask display onset in incorrect trials, in which enumeration failed due to stronger integration of mask and target visual information. This effect was timescale specific, distinguishing between segregation and integration of visual transients that were distant in time (long SOA). Conversely, for short SOA trials, mask onset evoked a stronger visual response when mask and targets were correctly segregated in time. Examination of the target-related response profile revealed the importance of an evoked α-phase reset for the segregation of those rapid visual transients. Investigating this precise mapping of the temporal relationships of visual signals onto electrophysiological responses highlights how the stream of visual information is carved up into discrete temporal windows that mediate between segregated and integrated percepts. Fragmenting the stream of visual information provides a means to stabilize perceptual events within one instant in time.

Chapter Six - Hyaluronan in the Healthy and Malignant Hematopoietic Microenvironment

The fate of both endogenous and transplanted stem cells is dependent on the functional status of the regulatory local microenvironment, which is compromised by disease and therapeutic intervention. The glycosaminoglycan hyaluronan (HA) is a critical component of the hematopoietic microenvironment. We summarize recent advances in our understanding of the role of HA in regulating mesenchymal stem cells, osteoblasts, fibroblasts, macrophages, and endothelium in bone marrow (BM) and their crosstalk within the hematopoietic microenvironment. HA not only determines the volume, hydration, and microfluidics of the BM interstitial space, but also, via interactions with specific receptors, regulates multiple cell functions including differentiation, migration, and production of regulatory factors. The effects of HA are dependent on the polymer size and are influenced by the formation of complexes with other molecules. In healthy BM, HA synthases and hyaluronidases form a molecular network that maintains extracellular HA levels within a discrete physiological window, but HA homeostasis is often perturbed in pathological conditions, including hematological malignancies. Recent studies have suggested that HA synthases may have functions beyond HA production and contribute to the intracellular regulatory machinery. We discuss a possible role for HA synthases, intracellular and extracellular HA in the malignant BM microenvironment, and resistance to therapy.

Discrete, Continuous and Conditional Multiple Window Scan Statistics

The distributions of discrete, continuous and conditional multiple window scan statistics are studied. The finite Markov chain imbedding technique has been applied to obtain the distributions of fixed window scan statistics defined from a sequence of Bernoulli trials. In this manuscript the technique is extended to compute the distributions of multiple window scan statistics and the exact powers for multiple pulse and Markov dependent alternatives. An application in blood component quality monitoring is provided. Numerical results are also given to illustrate our theoretical results.

Discrete, Continuous and Conditional Multiple Window Scan Statistics

The distributions of discrete, continuous and conditional multiple window scan statistics are studied. The finite Markov chain imbedding technique has been applied to obtain the distributions of fixed window scan statistics defined from a sequence of Bernoulli trials. In this manuscript the technique is extended to compute the distributions of multiple window scan statistics and the exact powers for multiple pulse and Markov dependent alternatives. An application in blood component quality monitoring is provided. Numerical results are also given to illustrate our theoretical results.

Solitons in Gaussian potential with spatially modulated nonlinearity

We investigated theoretically the existence, stability and propagation dynamics of fundamental and dipole solitons in the potential featuring locally Gaussian modulation of linear refractive index and out-of-phase nonlinearity. Fundamental solitons are stable in the moderate power region and the stability window shrinks with the depth of nonlinearity modulation, while there exist several discrete narrow stable windows for the dipole solitons. Also, a power-dependent shape transformation is found in the high power region for deep enough nonlinear modulation. The transverse mobility of solitons launched with a tilt angle was also discussed, and the results show the critical tilt angles for soliton deflecting from the channel increase with a decrease of the propagation constant. For the low energy soliton, only part of the soliton would keep oscillating in the channel and the other part would deflect away even if the tilt angle is smaller than the critical value.

Dynamic proteomics emphasizes the importance of selective mRNA translation and protein turnover during Arabidopsis seed germination.

During seed germination, the transition from a quiescent metabolic state in a dry mature seed to a proliferative metabolic state in a vigorous seedling is crucial for plant propagation as well as for optimizing crop yield. This work provides a detailed description of the dynamics of protein synthesis during the time course of germination, demonstrating that mRNA translation is both sequential and selective during this process. The complete inhibition of the germination process in the presence of the translation inhibitor cycloheximide established that mRNA translation is critical for Arabidopsis seed germination. However, the dynamics of protein turnover and the selectivity of protein synthesis (mRNA translation) during Arabidopsis seed germination have not been addressed yet. Based on our detailed knowledge of the Arabidopsis seed proteome, we have deepened our understanding of seed mRNA translation during germination by combining two-dimensional gel-based proteomics with dynamic radiolabeled proteomics using a radiolabeled amino acid precursor, namely [(35)S]-methionine, in order to highlight de novo protein synthesis, stability, and turnover. Our data confirm that during early imbibition, the Arabidopsis translatome keeps reflecting an embryonic maturation program until a certain developmental checkpoint. Furthermore, by dividing the seed germination time lapse into discrete time windows, we highlight precise and specific patterns of protein synthesis. These data refine and deepen our knowledge of the three classical phases of seed germination based on seed water uptake during imbibition and reveal that selective mRNA translation is a key feature of seed germination. Beyond the quantitative control of translational activity, both the selectivity of mRNA translation and protein turnover appear as specific regulatory systems, critical for timing the molecular events leading to successful germination and seedling establishment.

Automated acoustic detection and classification of small aircraft

Automated acoustic detection and classification of low flying aircraft can be used for the prevention of illicit operations. In this presentation, we review past techniques and a new acoustic classification and detection technique. The sound detection algorithm is based on locking in narrow frequency components in the spectra of the recorded aircraft sound. The classification algorithm uses tonal components in the spectral and cepstral domains using discrete time window peak picking. A set of chosen classifiers include: fundamental (pitch) frequency extracted by the cepstral analysis, frequency of tonal components with the maximal amplitude, power spectral estimate in various frequency bands, and number of peaks in predefined frequency and frequency windows. Various small single engine aircraft, ultralights, and helicopters are acoustically detected and classified as they approach the sensor. The algorithm enables simultaneous target detection, reduces noise sensitivity, and minimizes classifier feature space, while maintaining good classification separation. The acoustic classification algorithm was incorporated into the Acoustic Aircraft Detection system developed by Stevens. This combination allowed automated Doppler correction of the harmonic lines, the optimal part of the aircraft signal selection, and establishing classification merits based on aircraft track. [This work was funded by DHS S&T.]

Targeted DNA methylation by homology-directed repair in mammalian cells. Transcription reshapes methylation on the repaired gene

We report that homology-directed repair of a DNA double-strand break within a single copy Green Fluorescent Protein (GFP) gene in HeLa cells alters the methylation pattern at the site of recombination. DNA methyl transferase (DNMT)1, DNMT3a and two proteins that regulate methylation, Np95 and GADD45A, are recruited to the site of repair and are responsible for selective methylation of the promoter-distal segment of the repaired DNA. The initial methylation pattern of the locus is modified in a transcription-dependent fashion during the 15–20 days following repair, at which time no further changes in the methylation pattern occur. The variation in DNA modification generates stable clones with wide ranges of GFP expression. Collectively, our data indicate that somatic DNA methylation follows homologous repair and is subjected to remodeling by local transcription in a discrete time window during and after the damage. We propose that DNA methylation of repaired genes represents a DNA damage code and is source of variation of gene expression.

Low Intensity and Frequency Pulsed Electromagnetic Fields Selectively Impair Breast Cancer Cell Viability

IntroductionA common drawback of many anticancer therapies is non-specificity in action of killing. We investigated the potential of ultra-low intensity and frequency pulsed electromagnetic fields (PEMFs) to kill breast cancer cells. Our criteria to accept this technology as a potentially valid therapeutic approach were: 1) cytotoxicity to breast cancer cells and; 2) that the designed fields proved innocuous to healthy cell classes that would be exposed to the PEMFs during clinical treatment.MethodsMCF7 breast cancer cells and their normal counterparts, MCF10 cells, were exposed to PEMFs and cytotoxic indices measured in order to design PEMF paradigms that best kill breast cancer cells. The PEMF parameters tested were: 1) frequencies ranging from 20 to 50 Hz; 2) intensities ranging from 2 mT to 5 mT and; 3) exposure durations ranging from 30 to 90 minutes per day for up to three days to determine the optimum parameters for selective cancer cell killing.ResultsWe observed a discrete window of vulnerability of MCF7 cells to PEMFs of 20 Hz frequency, 3 mT magnitude and exposure duration of 60 minutes per day. The cell damage accrued in response to PEMFs increased with time and gained significance after three days of consecutive daily exposure. By contrast, the PEMFs parameters determined to be most cytotoxic to breast cancer MCF-7 cells were not damaging to normal MCF-10 cells.ConclusionBased on our data it appears that PEMF-based anticancer strategies may represent a new therapeutic approach to treat breast cancer without affecting normal tissues in a manner that is non-invasive and can be potentially combined with existing anti-cancer treatments.

Hemodynamic responses to speech and music in preverbal infants

Numerous studies have provided clues about the ontogeny of lateralization of auditory processing in humans, but most have employed specific subtypes of stimuli and/or have assessed responses in discrete temporal windows. The present study used near-infrared spectroscopy (NIRS) to establish changes in hemodynamic activity in the neocortex of preverbal infants (aged 4–11 months) while they were exposed to two distinct types of complex auditory stimuli (full sentences and musical phrases). Measurements were taken from bilateral temporal regions, including both anterior and posterior superior temporal gyri. When the infant sample was treated as a homogenous group, no significant effects emerged for stimulus type. However, when infants’ hemodynamic responses were categorized according to their overall changes in volume, two very clear neurophysiological patterns emerged. A high-responder group showed a pattern of early and increasing activation, primarily in the left hemisphere, similar to that observed in comparable studies with adults. In contrast, a low-responder group showed a pattern of gradual decreases in activation over time. Although age did track with responder type, no significant differences between these groups emerged for stimulus type, suggesting that the high- versus low-responder characterization generalizes across classes of auditory stimuli. These results highlight a new way to conceptualize the variable cortical blood flow patterns that are frequently observed across infants and stimuli, with hemodynamic response volumes potentially serving as an early indicator of developmental changes in auditory-processing sensitivity.

Glutathione redox dynamics and expression of glutathione-related genes in the developing embryo

Embryonic development involves dramatic changes in cell proliferation and differentiation that must be highly coordinated and tightly regulated. Cellular redox balance is critical for cell fate decisions, but it is susceptible to disruption by endogenous and exogenous sources of oxidative stress. The most abundant endogenous nonprotein antioxidant defense molecule is the tripeptide glutathione (γ-glutamylcysteinylglycine, GSH), but the ontogeny of GSH concentration and redox state during early life stages is poorly understood. Here, we describe the GSH redox dynamics during embryonic and early larval development (0–5 days postfertilization) in the zebrafish (Danio rerio), a model vertebrate embryo. We measured reduced and oxidized glutathione using HPLC and calculated the whole embryo total glutathione (GSHT) concentrations and redox potentials (Eh) over 0–120h of zebrafish development (including mature oocytes, fertilization, midblastula transition, gastrulation, somitogenesis, pharyngula, prehatch embryos, and hatched eleutheroembryos). GSHT concentration doubled between 12h postfertilization (hpf) and hatching. The GSH Eh increased, becoming more oxidizing during the first 12h, and then oscillated around −190mV through organogenesis, followed by a rapid change, associated with hatching, to a more negative (more reducing) Eh (−220mV). After hatching, Eh stabilized and remained steady through 120 hpf. The dynamic changes in GSH redox status and concentration defined discrete windows of development: primary organogenesis, organ differentiation, and larval growth. We identified the set of zebrafish genes involved in the synthesis, utilization, and recycling of GSH, including several novel paralogs, and measured how expression of these genes changes during development. Ontogenic changes in the expression of GSH-related genes support the hypothesis that GSH redox state is tightly regulated early in development. This study provides a foundation for understanding the redox regulation of developmental signaling and investigating the effects of oxidative stress during embryogenesis.

PIV uncertainty quantification by image matching

A novel method is presented to quantify the uncertainty of PIV data. The approach is a posteriori, i.e. the unknown actual error of the measured velocity field is estimated using the velocity field itself as input along with the original images. The principle of the method relies on the concept of super-resolution: the image pair is matched according to the cross-correlation analysis and the residual distance between matched particle image pairs (particle disparity vector) due to incomplete match between the two exposures is measured. The ensemble of disparity vectors within the interrogation window is analyzed statistically. The dispersion of the disparity vector returns the estimate of the random error, whereas the mean value of the disparity indicates the occurrence of a systematic error. The validity of the working principle is first demonstrated via Monte Carlo simulations. Two different interrogation algorithms are considered, namely the cross-correlation with discrete window offset and the multi-pass with window deformation. In the simulated recordings, the effects of particle image displacement, its gradient, out-of-plane motion, seeding density and particle image diameter are considered. In all cases good agreement is retrieved, indicating that the error estimator is able to follow the trend of the actual error with satisfactory precision. Experiments where time-resolved PIV data are available are used to prove the concept under realistic measurement conditions. In this case the ‘exact’ velocity field is unknown; however a high accuracy estimate is obtained with an advanced interrogation algorithm that exploits the redundant information of highly temporally oversampled data (pyramid correlation, Sciacchitano et al (2012 Exp. Fluids 53 1087–105)). The image-matching estimator returns the instantaneous distribution of the estimated velocity measurement error. The spatial distribution compares very well with that of the actual error with maxima in the highly sheared regions and in the 3D turbulent regions. The high level of correlation between the estimated error and the actual error indicates that this new approach can be utilized to directly infer the measurement uncertainty from PIV data. A procedure is shown where the results of the error estimation are employed to minimize the measurement uncertainty by selecting the optimal interrogation window size.

Dehiscences of the semicircular canals as discrete third window lesions of the inner ear

The aim of this study was to assess the role of high resolution multi-detector CT in diagnosis of different dehiscences of the semicircular canals (SCC). Material and MethodsThis study was conducted on 20 patients within one year interval. All the patients had given clinical diagnosis of dehiscences of the SSC by clinical examination and/or audiogram. Sixty-four MDCT was used in assessment of all patients. ResultsCongenital defects of the SCC were encountered in 9 cases (45%); acquired defects were encountered in 11 cases (55%). Among the congenital defects, superior and posterior SCC were involved in 6 and 3 patients (30 and 15%) respectively. Congenital defects of lateral SSC were not encountered in this study. Cholesteatoma was the most common single etiology causing defect within the SCC. ConclusionRadiological diagnosis of SCC dehiscences depends on the use of high resolution MDCT. Ultrathin reconstruction with MPR is mostly sufficient in accurate display of the defects. Primary congenital dehiscences do occur in the superior SCC but also less commonly within the posterior canal. In this study, lateral canal dehiscence was only acquired. Secondary semicircular canal dehiscences could be caused by cholesteatoma and temporal bony aggressive mass lesions.

Exposure to polychlorinated biphenyl (PCB) congeners measured shortly after giving birth and subsequent risk of maternal breast cancer before age 50

Discrete windows of susceptibility to toxicants have been identified for the breast, including in utero, puberty, pregnancy, and postpartum. We tested the hypothesis that polychlorinated biphenyls (PCBs) measured during the early postpartum predict increased risk of maternal breast cancer diagnosed before age 50. We analyzed archived early postpartum serum samples collected from 1959 to 1967, an average of 17 years before diagnosis (mean diagnosis age 43 years) for 16 PCB congeners in a nested case–control study in the Child Health and Development Studies cohort (N = 112 cases matched to controls on birth year). We used conditional logistic regression to adjust for lipids, race, year, lactation, and body mass. We observed strong breast cancer associations with three congeners. PCB 167 was associated with a lower risk (odds ratio (OR), 75th vs. 25th percentile = 0.2, 95 % confidence interval (95 % CI) 0.1, 0.8) as was PCB 187 (OR, 75th vs. 25th percentile = 0.4, 95 % CI 0.1, 1.1). In contrast, PCB 203 was associated with a sixfold increased risk (OR, 75th vs. 25th percentile = 6.3, 95 % CI 1.9, 21.7). The net association of PCB exposure, estimated by a post-hoc score, was nearly a threefold increase in risk (OR, 75th vs. 25th percentile = 2.8, 95 % CI 1.1, 7.1) among women with a higher proportion of PCB 203 in relation to the sum of PCBs 167 and 187. Postpartum PCB exposure likely also represents pregnancy exposure, and may predict increased risk for early breast cancer depending on the mixture that represents internal dose. It remains unclear whether individual differences in exposure, response to exposure, or both explain risk patterns observed.

DWT 영역에서의 주파수 정보를 활용한 가변 윈도우 기반의 스테레오 정합 알고리즘

In this paper we propose a new stereo matching algorithm which is suitable for application to obtain depth information with high-speed in stereoscopic camera environment. For satisfying these condition we propose a new adaptive stereo matching technique using frequency information in discrete wavelet (DWT) domain and variable matching window. The size of the matching window is selected by analysis of the local property of the image in spatial domain and the feature and scaling factor of the matching window is selected by the frequency property in the frequency domain. For using frequency information we use local DWT and global DWT. We identified that the proposed technique has better peak noise to signal ratio (PSNR) than the fixed matching techniques with similar complexity.

Resonant transmission through a multiple periodic scattering system

We investigate the propagation and transmission of electromagnetic (EM) waves in the subwavelength regime when a multiple periodic scattering system (MPSS) is illuminated by a monochromatic plane wave. This system has a cascaded structure with square hole arrays periodically perforated on a metal slab with arbitrary slab thickness and arbitrary air-gap. The framework of this paper is based on a modal expansion theory, in which the EM fields in pure vacuum are expanded in terms of plane waves, while those in the holes of the slab are expressed in terms of waveguide modes. The boundary conditions for the EM waves lead to a system of equations whose solution can be obtained quasianalytically in a monomodal approximation method. We study the transmission spectrum and field distribution in the MPSS, varying geometrical parameters such as the air-gap and/or number N of slabs in the context of symmetrical and asymmetrical geometries. We find that an MPSS with N ≥ 2 provides discrete transmission windows whose resonance order linearly increases against N and the associated resonance wavelengths are confined to a specific finite band for large N. The EM fields at the resonance states are quite uniquely distributed in the MPSS, depending not only on the resonance wavelength, but also either on even N or on odd N. We also demonstrate that the transmission of the EM energy is strongly boosted by the evanescent electric fields mirror-symmetrically distributed in the air-gaps of the MPSS.

Cholesteryl ester acyl oxidation and remodeling in murine macrophages: formation of oxidized phosphatidylcholine

Cholesterol is an essential component of eukaryotic cell membranes, regulating fluidity and permeability of the bilayer. Outside the membrane, cholesterol is esterified to fatty acids forming cholesterol esters (CEs). Metabolism of CEs is characterized by recurrent hydrolysis and esterification as part of the CE cycle; however, since recombinant 15-lipoxygenase (15-LO) was shown to oxidize cholesteryl linoleate of LDL, there has been interest in CE oxidation, particularly in the context atherogenesis. Studies of oxidized CE (oxCE) metabolism have focused on hydrolysis and subsequent reverse cholesterol transport with little emphasis on the fate the newly released oxidized fatty acyl component. Here, using mass spectrometry to analyze lipid oxidation products, CE metabolism in murine peritoneal macrophages was investigated. Ex vivo macrophage incubations revealed that cellular 15-LO directly oxidized multiple CE substrates from intracellular stores and from extracellular sources. Freshly harvested murine macrophages also contained 15-LO-specific oxCEs, suggesting the enzyme may act as a CE-oxidase in vivo. The metabolic fate of oxCEs, particularly the hydrolysis and remodeling of oxidized fatty acyl chains, was also examined in the macrophage. Metabolism of deuterated CE resulted in the genesis of deuterated, oxidized phosphatidylcholine (oxPC). Further experiments revealed these oxPC species were formed chiefly from the hydrolysis of oxidized CE and subsequent reacylation of the oxidized acyl components into PC.

Embryonic birthdate of hypothalamic leptin-activated neurons in mice.

The hypothalamus plays a critical role in the regulation of energy balance. Neuroanatomical and mouse genetic data have defined a core circuitry in the hypothalamus that mediates many of the effects of leptin on feeding and energy balance regulation. The present study used 5-bromo-2'-deoxyuridine (a marker of dividing cells) and a neuronal marker to systematically examine neurogenesis in the mouse embryonic hypothalamus, particularly the birth of neurons that relay leptin signaling. The vast majority of neurons in hypothalamic nuclei known to control energy balance is generated between embryonic days (E) 12 and E16, with a sharp peak of neurogenesis occurring on E12. Neurons in the dorsomedial and paraventricular nuclei and the lateral hypothalamic area are born between E12 and E14. The arcuate and ventromedial nuclei exhibit a relatively longer neurogenic period. Many neurons in these nuclei are born on E12, but some neurons are generated as late as E16. We also examined the birth of leptin-activated cells by coupling the 5-bromo-2'-deoxyuridine staining with cFos immunohistochemistry. Remarkably, the majority of leptin-activated cells in the adult hypothalamus were also born during a discrete developmental window on E12. These results provide new insight into the development of hypothalamic neurons that control feeding and identify important developmental periods when alterations in the intrauterine environment may affect hypothalamic neurogenesis and produce long-term consequences on hypothalamic cell numbers.

Changes of regional climate variability in central Europe during the past 250 years

The paper uses the data potential of very long and homogenized instrumental climate time series in the south central Europe for analyzing one feature which is very dominant in the climate change debate --whether anthropogenic climate warming causes or goes along with an increase of climate extremes. The monthly resolved data of the HISTALP data collection provide 58 single series for the three climate elements, air pressure, air temperature and precipitation, that start earlier than 1831 and extend back to 1760 in some cases. Trends and long-term low frequent climate evolution is only shortly touched in the paper. The main goal is the analysis of trends or changes of high frequent interannual and interseasonal variability. In other words, it is features like extremely hot summers, very cold winters, excessively dry or wet seasons which the study aims at. The methods used are based on detrended highpass series whose variance is analyzed in discrete 30-year windows moving over the entire instrumental period. The analysis of discrete subintervals relies on the unique number of 8 (for precipitation 7) such “normal periods”. The second approach is based on the same subintervals though not in fixed but moving windows over the entire instrumental period. The first result of the study is the clear evidence that there has been no increase of variability during the past 250 years in the region. The second finding is similar but concentrates on the recent three decades which are of particular interest because they are the first 30 years with dominating anthropogenic greenhouse gas forcing. We can show that also this recent anthropogenic normal period shows no widening of the PDF (probability density function) compared to the preceding ones. The third finding is based on the moving window technique. It shows that interannual variability changes show a clear centennial oscillating structure for all three climate elements in the region. For the time being we have no explanation for this empirical evidence. We argue that it should not be an artifact of any remaining data problems, but of course a centennial cyclic effect based on 250 years of data only is not really well consolidated in terms of sample length. But it is at least an interesting new feature and the subject is open for scientific discussion and for further studies dealing with circulation effects, long-term memories in the oceans etc.