Dynamic Intensity Changes Research Articles

Land use and land cover dynamics: Implications for thermal stress and energy demands

This study examined the interaction between land use and land cover (LULC) dynamics, trend and thermal stress distribution using the universal thermal comfort index (UTCI) and different LULC classifications under two Coupled Model Intercomparison Project Phase 6 (CMIP6) Shared Socioeconomic Pathways (i.e., SSP 370 and 585) climate and land use scenarios for the historical (1959–2014) and future period (2045–2100). The moderate to strong cold stress in the annual and winter climatology in the midlatitudes was replaced by no thermal stress in the summer, while the summertime ranged from moderate to strong heat stress. A negative correlation was observed between thermal stress and southern hemispheric primary forests. Perennial croplands had the most dynamic changes in intensity during the historical period. Primary and secondary forests had an active influence on global thermal stress. Areas in the tropics recording moderate heat stress coincided with secondary nonforest, pastureland, and annual cropland expansions. The conversion of forest to range land and croplands and the subsequent negative forest trends increased the severity of thermal stress. The future projection showed intense thermal stress; however, the SSP-585 signals were more potent. As a result, cooling demands will rise, and heating demands will decline, yet, improved thermal comfort necessitates a higher cooling capacity, especially in the summer. Thermal stress may make it difficult for many cooling systems to meet people's energy demands. These could be a driving factor in shaping better land use policies, improving energy demand preparedness, and elucidating the potentially severe impacts of thermal stress.

Shrinking gate fluorescence correlation spectroscopy yields equilibrium constants and separates photophysics from structural dynamics

Fluorescence correlation spectroscopy is a versatile tool for studying fast conformational changes of biomolecules especially when combined with Förster resonance energy transfer (FRET). Despite the many methods available for identifying structural dynamics in FRET experiments, the determination of the forward and backward transition rate constants and thereby also the equilibrium constant is difficult when two intensity levels are involved. Here, we combine intensity correlation analysis with fluorescence lifetime information by including only a subset of photons in the autocorrelation analysis based on their arrival time with respect to the excitation pulse (microtime). By fitting the correlation amplitude as a function of microtime gate, the transition rate constants from two fluorescence-intensity level systems and the corresponding equilibrium constants are obtained. This shrinking-gate fluorescence correlation spectroscopy (sg-FCS) approach is demonstrated using simulations and with a DNA origami-based model system in experiments on immobilized and freely diffusing molecules. We further show that sg-FCS can distinguish photophysics from dynamic intensity changes even if a dark quencher, in this case graphene, is involved. Finally, we unravel the mechanism of a FRET-based membrane charge sensor indicating the broad potential of the method. With sg-FCS, we present an algorithm that does not require prior knowledge and is therefore easily implemented when an autocorrelation analysis is carried out on time-correlated single-photon data.

Mismatch Negativity on Presentation of Amplitude-Modulated Sound Signals

The studies reported here addressed analysis of the N1 and P2 components and mismatch negativity (MMN) on discrimination of signals with dynamic changes in intensity in different acoustic contexts. Changes in context in the conditions of the oddball paradigm were created on the basis that each stimulus operated both as a standard and as a deviant in different series, such that the physical differences between signals remained unaltered and their functional relationship flipped to the opposite. Three types of sound signal were used: stimuli with constant intensity and two amplitude-modulated stimuli (linear and stepwise, each with an increase or decrease in intensity). Increases and decreases in the intensity of deviant stimuli induced MMN in the late latency period (>250 msec) without overlap with the N1 component. The difference in signals with linear and stepwise amplitude modulation indexed by mismatch negativity was determined by the direction of deviation in the structure of the sound series. Increment MMN anticipated decrement MMN by 90–100 msec regardless of the type of modulation. Amplitude differences were seen in responses to deviants with stepwise modulation in the context of consistent standards: increment MMN was greater than decrement MMN. The acoustic context affected only increment MMN. These results are consistent with views of the asymmetry in the perception of increasing and decreasing sound intensity, associated with their different biological significance.

FRNET: FLATTENED RESIDUAL NETWORK FOR INFANT MRI SKULL STRIPPING.

Skull stripping for brain MR images is a basic segmentation task. Although many methods have been proposed, most of them focused mainly on the adult MR images. Skull stripping for infant MR images is more challenging due to the small size and dynamic intensity changes of brain tissues during the early ages. In this paper, we propose a novel CNN based framework to robustly extract brain region from infant MR image without any human assistance. Specifically, we propose a simplified but more robust flattened residual network architecture (FRnet). We also introduce a new boundary loss function to highlight ambiguous and low contrast regions between brain and non-brain regions. To make the whole framework more robust to MR images with different imaging quality, we further introduce an artifact simulator for data augmentation. We have trained and tested our proposed framework on a large dataset (N=343), covering newborns to 48-month-olds, and obtained performance better than the state-of-the-art methods in all age groups.

Perceptual Temporal Asymmetry Associated with Distinct ON and OFF Responses to Time-Varying Sounds with Rising versus Falling Intensity: A Magnetoencephalography Study.

This magnetoencephalography (MEG) study investigated evoked ON and OFF responses to ramped and damped sounds in normal-hearing human adults. Two pairs of stimuli that differed in spectral complexity were used in a passive listening task; each pair contained identical acoustical properties except for the intensity envelope. Behavioral duration judgment was conducted in separate sessions, which replicated the perceptual bias in favour of the ramped sounds and the effect of spectral complexity on perceived duration asymmetry. MEG results showed similar cortical sites for the ON and OFF responses. There was a dominant ON response with stronger phase-locking factor (PLF) in the alpha (8–14 Hz) and theta (4–8 Hz) bands for the damped sounds. In contrast, the OFF response for sounds with rising intensity was associated with stronger PLF in the gamma band (30–70 Hz). Exploratory correlation analysis showed that the OFF response in the left auditory cortex was a good predictor of the perceived temporal asymmetry for the spectrally simpler pair. The results indicate distinct asymmetry in ON and OFF responses and neural oscillation patterns associated with the dynamic intensity changes, which provides important preliminary data for future studies to examine how the auditory system develops such an asymmetry as a function of age and learning experience and whether the absence of asymmetry or abnormal ON and OFF responses can be taken as a biomarker for certain neurological conditions associated with auditory processing deficits.

Amplification of the effects of magnetization exchange by (31) P band inversion for measuring adenosine triphosphate synthesis rates in human skeletal muscle.

The goal of this study was to amplify the effects of magnetization exchange between γ-adenosine triphosphate (ATP) and inorganic phosphate (Pi) for evaluation of ATP synthesis rates in human skeletal muscle. The strategy works by simultaneously inverting the (31) P resonances of phosphocreatine (PCr) and ATP using a wide bandwidth, adiabatic inversion radiofrequency pulse followed by observing dynamic changes in intensity of the noninverted Pi signal versus the delay time between the inversion and observation pulses. This band inversion technique significantly delays recovery of γ-ATP magnetization; consequently, the exchange reaction, Pi ↔ γ-ATP, is readily detected and easily analyzed. The ATP synthesis rate measured from high-quality spectral data using this method was 0.073 ± 0.011 s(-1) in resting human skeletal muscle (N = 10). The T1 of Pi was 6.93 ± 1.90 s, consistent with the intrinsic T1 of Pi at this field. The apparent T1 of γ-ATP was 4.07 ± 0.32 s, about two-fold longer than its intrinsic T1 due to storage of magnetization in PCr. Band inversion provides an effective method to amplify the effects of magnetization transfer between γ-ATP and Pi. The resulting data can be easily analyzed to obtain the ATP synthesis rate using a two-site exchange model.

Evaluation of advanced data analysis techniques on time resolved FT-IR spectroscopy data of photo-copolymerization reactions

Time resolved FT-IR spectroscopy in combination with various data analysis techniques has been employed to determine the kinetics of photo-copolymerization reactions. 2D-correlation spectroscopy of the dynamic intensity changes in the 3D-IR data of these complex formulations clearly showed added value in the interpretation of overlapping vibrational bands. Other analytical data evaluation techniques which where applied are univariate method, peak fitted deconvolution and multivariate techniques like SIMPLISMA and multivariate curve resolution (MCR). Kinetic reaction profiles of homo- and copolymerizations have been extracted for each reactive monomer.

The Doppler effect is not what you think it is: dramatic pitch change due to dynamic intensity change.

Historically, auditory pitch has been considered to be a function of acoustic frequency, with only a small effect being due to absolute intensity. Yet we found that when tones are Doppler shifted so that frequency drops, the pitch dramatically rises and falls, closely following the pattern of dynamic intensity change. We show that continuous intensity change can produce pitch variation comparable to a frequency change approaching an octave. This effect opposes and is an order of magnitude larger than the well-known effect of discrete intensity change in the frequency range employed. We propose that the perceptual interaction of continuous changes in pitch and loudness reflects a natural correlation between changes in frequency and intensity that is neurally encoded to facilitate the parsing and processing of meaningful acoustic patterns.

Dynamic intensity change influences perceived pitch: Attentional differences between musicians and nonmusicians

The influence of dynamic intensity change on the terminal pitch of ascending frequency glides was tested as a function of terminal frequency and musical experience. Previous work has shown that dynamic intensity change influences perceived pitch [J. G. Neuhoff and M. K. McBeath, J. Exp. Psychol.: Human Percept. Perform. 22, 970–985 (1996)]. In the current study, musicians and nonmusicians were presented with dynamic tones that changed in both frequency and intensity, and made real-time judgments about perceived pitch change. Results show that for both musicians and nonmusicians, the influence of intensity change on perceived pitch lessened as the terminal frequency approached an octave. Musicians were less susceptible to the effects of intensity change for falling intensity but not for rising intensity. The findings suggest that musicians may have better selective attention to dynamic auditory stimulus dimensions, and the influence of a tonal schema may reduce the influence of intensity change on perceived pitch. The results imply an interplay of musical and nonmusical listening strategies and demonstrate that the two are not mutually exclusive.

Auditory pitch influenced dramatically by dynamic intensity change

Historically, auditory pitch is considered to be principally a function of acoustic frequency with only a small effect due to absolute intensity. Yet, when tones are Doppler shifted, the pitch dramatically rises and falls with dynamic intensity. This study uses a matching procedure to document the magnitude of pitch drop of dynamic Doppler stimuli. Listeners heard Doppler-shifted tones with a mean frequency of either 1046 or 175 Hz, a total fall of 2 semitones, and an intensity change of 58 to 86 dB and back to 58 dB. They compared this drop to a pair of 75-dB, 0.25-s discrete tones that dropped in frequency by intervals ranging from 0 to 24 semitones. The average match between experienced sizes of Doppler and discrete pitch change occurred at a discrete drop of 8 semitones, four times larger than the actual Doppler frequency change. This effect opposes and is an order of magnitude larger than the well known effect due to discrete intensity change. It is proposed that the interaction between dynamic pitch and loudness reflects a natural correlation between changes in frequency and intensity that is neurally encoded to facilitate processing of meaningful acoustic patterns.

The interaction of pitch and loudness in dynamic stimuli: Beyond the Doppler illusion

Listeners tend to experience rising pitch even though frequency falls as a sound source approaches. The phenomenon, called the Doppler illusion [J. G. Neuhoff and M. K. McBeath, J. Exp. Psychol. Hum. Percept. Perform. 22, 970–985 (1996)], shows that dynamic intensity change influences perceived pitch in a way that is qualitatively different from discrete static intensity change. Two new studies show a dynamic influence of intensity change on perceived pitch and a dynamic influence of frequency change on perceived loudness. Listeners were presented with square wave tones of either rising, falling, or constant intensity that either rose, fell, or remained constant in frequency for 6 s. Listeners responded in real time to either changes in pitch or loudness by moving a response wheel. It was found that dynamic intensity sweeps contribute to the perception of dynamic pitch change in the direction of the intensity sweep. In addition, dynamic frequency sweeps contribute to the perception of perceived loudness change in the direction of the frequency sweep. The results imply that pitch and loudness perception interact under dynamic conditions in a way that cannot be predicted by perceptual models derived from the presentation of discrete static tones.

The Doppler illusion: The influence of dynamic intensity change on perceived pitch.

The Doppler illusion: The influence of dynamic intensity change on perceived pitch.

The Doppler illusion: the influence of dynamic intensity change on perceived pitch.

Four studies illustrate a new auditory illusion associated with the Doppler effect and demonstrate a new influence of dynamic intensity change on perceived pitch. Experiment 1 confirmed the existence of a popular belief that the pitch of a moving sound source rises as the source approaches. Because there is no corresponding rise in frequency, the authors refer to the perceived pitch rise as the Doppler illusion. Experiment 2 confirmed that the effect occurs perceptually, so the belief in a "naive principle" of physics has a perceptual basis. Experiment 3 confirmed the effect does not occur under matched static conditions. Experiment 4 showed that the influence of dynamic intensity change on perceived pitch occurs outside the realm of Doppler stimuli. The findings support a dynamic dimensional interaction of pitch and loudness, with marked differences in the perception of pitch and loudness under static and dynamic conditions.