Low Transition Probability Research Articles

Effects of Contextual Predictability and Transitional Probability on Eye Movements During Reading.

In 2 eye-movement experiments, the authors tested whether transitional probability (the statistical likelihood that a word precedes or follows another word) affects reading times and whether this occurs independently from contextual predictability effects. Experiment 1 showed early effects of predictability, replicating S. A. McDonald and R. C. Shillcock's (2003a) finding that words with a high transitional probability (defeat following accept) are read faster than words with a low transitional probability (losses following accept). However, further analyses suggested that the transitional probability effect was likely due to differences in predictability rather than transitional probability. Experiment 2, using a better controlled set of items, again showed an effect of predictability, but no effect of transitional probability. The authors conclude that effects of transitional probability are part of regular predictability effects. Their data also show that predictability effects are detectable very early in the eye-movement record and between contexts that are weakly constraining.

Modelling Low Pay Transition Probabilities, Accounting for Panel Attrition, Non-Response, and Initial Conditions

We model annual low pay transition probabilities taking account of three potentially endogenous selections: two sample drop-out mechanisms (panel attrition, non-employment) and ‘initial conditions’ (base-year low pay status). This model, and variants that ignore one or more of these selection mechanisms, are fitted to data for men from the British Household Panel Survey. Tests of the ignorability of the endogenous selection mechanisms suggest that ‘economic’ selection mechanisms such as initial conditions and retention of employment are more important than the ‘survey’ selection mechanism (attrition). However, consistent with related US research, relatively simple models provide estimates of covariate effects that differ little from the estimates from the complicated models.

Impact of Nutrition and Exposure to the ParasitePlagiorchis elegans(Trematoda: Plagiorchiidae) on the Development ofAedes aegypti(Diptera: Culicidae): Analysis by Time-Dependent Transition Probabilities

The effects of food availability and the presence of the entomopathogenic digenean parasite Plagiorchis elegans (Rudolphi) on the probability of Aedes aegypti (L.) preimagos to transform from one developmental stage to the next over consecutive 24- or 48-h periods were quantified. Under conditions of low food availability, 24- and 48-h transition probabilities for all larval instars to the next were reduced. Increases in food availability reversed this process, causing significant decreases in same-stage transition probabilities. However, as transition to successive stages increased among first, second, third, and fourth instars, there was a concomitant, significant increase in first- and fourth-instar mortality. Exposure to P. elegans cercariae caused significant decreases in the 24- and 48-h same-state probabilities for all preimago stages. Successive stage transitions for first, second, and third instars were significantly increased, whereas those of fourth instars and pupae were significantly decreased with exposure to parasites. Mortality among all preimago stages increased significantly with exposure, but was highest among fourth instars and pupae. There were strong food-by-parasite interaction effects among first, second, and third instars. Differences in transition probabilities increased with increasing food levels between control and parasite-exposed sets. Whereas there was no significant interaction effect between food and the presence of the parasite in pupae, significantly more fourth instars died in response to parasite exposure and the food-by-parasite interaction effect on the probability of fourth instars transforming to pupae over 48 h approached significance. Adult emergence reflected the above effects. These findings are discussed in the context of the Ae. aegypti/P. elegans host/parasite association and the role of entomopathogenic digeneans as natural enemies and their potential as agents in the biological control of mosquitoes.

Transitioning into and out of large-effect drinking in young adulthood.

As individuals age beyond the college years into young adulthood, many exhibit a tendency to moderate or mature out alcohol involvement. The current study classified effect-drinking statuses in young adults and examined transitions among statuses using latent transition analysis, a latent variable state-sequential model for longitudinal data. At 3 occasions over 7 years (Years 1, 4, and 7), 443 men (47%) and women (mean age of both at baseline = 18.5 years; 51% with family history of alcoholism) responded to 3 past-30-day items assessing drinking and subjective effects of drinking: whether the respondent drank alcohol, felt high, and felt drunk. Latent statuses included abstainers (14% at Year 1), limited-effect drinkers (8%), moderate-effect drinkers (23%), and large-effect drinkers (54%). Respondents with family history of alcoholism were less likely to transition out of large-effect drinking than those without family history. Men exhibited more severe initial effect-drinking statuses and lower transition probabilities into less severe effect-drinking statuses than women.

Transitioning into and out of large-effect drinking in young adulthood.

As individuals age beyond the college years into young adulthood, many exhibit a tendency to moderate or "mature out of" alcohol involvement. The current study classified effect-drinking statuses in young adults and examined transitions among statuses using latent transition analysis, a latent variable state-sequential model for longitudinal data. At 3 occasions over 7 years (Years 1, 4, and 7), 443 men (47%) and women (mean age of both at baseline = 18.5 years; 51% with family history of alcoholism) responded to 3 past-30-day items assessing drinking and subjective effects of drinking: whether the respondent drank alcohol, felt high, and felt drunk. Latent statuses included abstainers (14% at Year 1), limited-effect drinkers (8%), moderate-effect drinkers (23%), and large-effect drinkers (54%). Respondents with family history of alcoholism were less likely to transition out of large-effect drinking than those without family history. Men exhibited more severe initial effect-drinking statuses and lower transition probabilities into less severe effect-drinking statuses than women.

A new scheme for trace determination of chromium using electrothermal atomization-laser induced fluorescence spectrometry

The determination of chromium (Cr) in water, gastrointestinal perfusates and serum samples by laser induced fluorescence in an electrothermal atomizer (ETA-LIF) has been investigated. Laser radiation used to excite Cr at 236.471 nm is generated by frequency doubling the output of a tunable dye laser. Fluorescence emissions are observed at 302.2 nm or 357.9 nm. Due to the low transition probability of the Cr excitation transition, excitation is performed using laser pulse energies of approximately 100 µJ per pulse. Atomization is performed in a commercial graphite furnace using pyrolytically coated graphite tubes without L'vov platforms. The optimized temperatures for ashing and atomization have been found to be 1300 °C and 2500 °C, respectively. The limit of detection for Cr in water by the ETA-LIF technique is 80 fg, which corresponds to 4 pg mL−1 in 20 µL sample volumes. The analytical approach has been utilized for the determination of Cr in biological fluids. Prior to analysis, gastrointestinal perfusate solutions and serum samples were diluted 1 + 1and 1 + 49, respectively, using 18 MΩ deionized water. The analysis of these samples has been evaluated using two different matrix modifiers [25 µg per 10 µL Mg(NO3)2 and 2% TritonX-100] and without a matrix modifier.

Spike-driven synaptic plasticity: theory, simulation, VLSI implementation.

We present a model for spike-driven dynamics of a plastic synapse, suited for aVLSI implementation. The synaptic device behaves as a capacitor on short timescales and preserves the memory of two stable states (efficacies) on long timescales. The transitions (LTP/LTD) are stochastic because both the number and the distribution of neural spikes in any finite (stimulation) interval fluctuate, even at fixed pre- and postsynaptic spike rates. The dynamics of the single synapse is studied analytically by extending the solution to a classic problem in queuing theory (Takacs process). The model of the synapse is implemented in aVLSI and consists of only 18 transistors. It is also directly simulated. The simulations indicate that LTP/LTD probabilities versus rates are robust to fluctuations of the electronic parameters in a wide range of rates. The solutions for these probabilities are in very good agreement with both the simulations and measurements. Moreover, the probabilities are readily manipulable by variations of the chip's parameters, even in ranges where they are very small. The tests of the electronic device cover the range from spontaneous activity (3-4 Hz) to stimulus-driven rates (50 Hz). Low transition probabilities can be maintained in all ranges, even though the intrinsic time constants of the device are short (approximately 100 ms). Synaptic transitions are triggered by elevated presynaptic rates: for low presynaptic rates, there are essentially no transitions. The synaptic device can preserve its memory for years in the absence of stimulation. Stochasticity of learning is a result of the variability of interspike intervals; noise is a feature of the distributed dynamics of the network. The fact that the synapse is binary on long timescales solves the stability problem of synaptic efficacies in the absence of stimulation. Yet stochastic learning theory ensures that it does not affect the collective behavior of the network, if the transition probabilities are low and LTP is balanced against LTD.

Confocal Fluorescence Lifetime Imaging Microscopy (FLIM) at the Single Molecule Level

We report on confocal fluorescence lifetime imaging microscopy (CFLIM) of single dye molecules adsorbed on glass surface. Applying a short-pulse diode laser emitting at 635 nm with a repetition rate of 64 MHz we studied the time-resolved identification of individual carbocyanine and oxazine dyes via their characteristic fluorescence lifetimes of 2.06±0.37 ns (Cy5) and 3.89±0.91 ns (JA242). Fluctuations in fluorescence intensity and lifetime of individual adsorbed molecules were investigated with millisecond time resolution. These jumps exhibit short off-states τoff of 0.5 ms which can be ascribed to the triplet state lifetime under dry conditions with an intersystem crossing yield YISC of ∼0.2 %. Besides triplet states, other quantum jumps into longer lived states (several milliseconds) with lower transition probability were observed. The correlation of rotational and spectral jumps of single and coupled fluorophores with changes in the observed fluorescence lifetime are discussed.

Confocal Fluorescence Lifetime Imaging Microscopy (FLIM) at the Single Molecule Level

We report on confocal fluorescence lifetime imaging microscopy (CFLIM) of single dye molecules adsorbed on glass surface. Applying a short-pulse diode laser emitting at 635 nm with a repetition rate of 64 MHz we studied the time-resolved identification of individual carbocyanine and oxazine dyes via their characteristic fluorescence lifetimes of 2.06±0.37 ns (Cy5) and 3.89±0.91 ns (JA242). Fluctuations in fluorescence intensity and lifetime of individual adsorbed molecules were investigated with millisecond time resolution. These jumps exhibit short off-states τoff of 0.5 ms which can be ascribed to the triplet state lifetime under dry conditions with an intersystem crossing yield YISC of ∼0.2 %. Besides triplet states, other quantum jumps into longer lived states (several milliseconds) with lower transition probability were observed. The correlation of rotational and spectral jumps of single and coupled fluorophores with changes in the observed fluorescence lifetime are discussed.

Low Pay Dynamics and Transition Probabilities

This paper models low pay transitions in Britain using a bivariate probit model with endogenous selection to address the ‘initial conditions’problem and parental variables as instruments. The exogeneity of the initial state is strongly rejected and results in considerable overstatement of theeffects of explanatory factors. The probability of being low paid dependsstrongly on low pay in the previous year. Restricting attention to those who remain employees results in an overstatement of the probability of the low paid moving up the earnings distribution, but is not found to have much effect on the estimated effects of explanatory variables.

The effect of molecular structure on the photophysical behavior of substituted styryl pyrazine derivatives

Six styryl pyrazine compounds, some of which have steric hindrance to rotate and some have twist freedom, were synthesized in this work. The effects of solvent polarity and viscosity on the photophysical and luminescent behavior of these compounds were preliminarily studied. Results indicated that the blocking of the double-bond twist by a sufficiently rigid bridge increases fluorescence quantum yields dramatically and the rotation of a single bond connecting the double bond and the phenyl group is favorable to form a single-bond twisted state (T*), which is the state responsible for the main channel of fluorescence emission. The reason for the higher fluorescence quantum yield of distyryl pyrazine was thought to be involved with the lower probability of transition from the Frank-Condon state (S1) to the phantom state (P*). Studies were also extended to develop a novel probe to detect the special microviscosity.

Biological mediation of stochastic peritidal carbonate accumulation

Research Article| September 01, 1997 Biological mediation of stochastic peritidal carbonate accumulation Bruce H. Wilkinson; Bruce H. Wilkinson 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Search for other works by this author on: GSW Google Scholar Carl N. Drummond; Carl N. Drummond 2Department of Geosciences, Indiana-Purdue University Fort Wayne, Fort Wayne, Indiana 46805-1499 Search for other works by this author on: GSW Google Scholar Nathaniel W. Diedrich; Nathaniel W. Diedrich 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Search for other works by this author on: GSW Google Scholar Edward D. Rothman Edward D. Rothman 3Department of Statistics, University of Michigan, Ann Arbor, Michigan 48109-1027 Search for other works by this author on: GSW Google Scholar Author and Article Information Bruce H. Wilkinson 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Carl N. Drummond 2Department of Geosciences, Indiana-Purdue University Fort Wayne, Fort Wayne, Indiana 46805-1499 Nathaniel W. Diedrich 1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Edward D. Rothman 3Department of Statistics, University of Michigan, Ann Arbor, Michigan 48109-1027 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1997) 25 (9): 847–850. https://doi.org/10.1130/0091-7613(1997)025<0847:BMOSPC>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Bruce H. Wilkinson, Carl N. Drummond, Nathaniel W. Diedrich, Edward D. Rothman; Biological mediation of stochastic peritidal carbonate accumulation. Geology 1997;; 25 (9): 847–850. doi: https://doi.org/10.1130/0091-7613(1997)025<0847:BMOSPC>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Exponential thickness frequencies of peritidal carbonate units in the Lower Ordovician Kindblade and West Spring Creek Formations at Ardmore, Oklahoma, are readily interpreted in a context of probabilities of upsection transition from one lithology to another. These largely reflect Poisson (random) processes of deposition from suspended load, traction load, and microbialitic accumulation. Although grainy to muddy particulate and cyanobacterial elements exhibit nearly equal ranges of unit thickness, carbonate generation and/or entrapment via algally mediated processes was less likely to lapse and therefore led to lower probability of transition to some other sediment type. The mean thickness of microbially bound units is roughly double those from the physical transport and deposition of particulate material. Greater persistence of algal accumulation probably related to intrinsically higher biologically induced rates of carbonate precipitation and/or binding by cyanobacteria. Stratigraphic intervals between successive occurrences of suspended load, traction load, and microbial units are also closely approximated by exponential frequency distributions for which regression slopes define probabilities of upsection recurrence of a particular sediment type. Values for grainy and algal carbonates are similar and are nearly twice that of muddy suspended-load units. Although biological processes resulted in significantly lower transition probabilities for thrombolitic bioherms and cryptalgal laminites, spatial dominance of carbonate mud across the region led to higher rates of stratigraphic recurrence and a volumetric dominance of muddy lithologies in the Ardmore sequence. Poissonian distributions of unit stratigraphic duration and recurrence suggest a significant component of haphazard variation in the type and amount of accumulated carbonate sediment. If deposition was influenced by extrabasinal forcing, such control must have been nearly random in both secular and spatial dimensions of water depth change. Stratigraphic durations and recurrences in this sequence more closely reflect the inherently stochastic nature of carbonate accumulation in epicratonic platformal settings than any influence of rhythmic eustatic forcing. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Upconversion properties of Er 3+ doped lead silicate glasses

We report the spectroscopic behaviour of the Er 3+ ion in two lead silicate glasses containing different concentrations of PbO. Evidence is given for blue and green upconversion fluorescence in the two Er 3+ doped lead silicate glasses with the use of 650 nm, 800 nm and 1.5 µm excitation. Analysis of the results shows that upconversion occurs via the sequential absorption of photons from the metastable 4I 13/2 state. Furthermore, we show that upconversion is facilitated due to the low radiative transition probabilities and to the inefficient multiphonon relaxation.

Does the classification system fit disease progression in perinatal human immunodeficiency virus infection?

The objective was to test the applicability of the new classification for paediatric human immonodeficiency virus infection. The person-time of each state, transition probabilities and survival (+/- standard errors) at 5 years, and median sojourn-time were calculated on 39 perinatally infected children followed up from the first month of life for a median of 64.5 (1.2-120.1) months. The person-times of the N2, N3, B1, C1, and C2 states were low. The transition probabilities and sojourn-times were similar for A (48.1 +/- 10.8%; 63.5 months), B (50.5 +/- 15.5%; 44.9 months) and C (74.6 +/- 15.1%; 43.1 months) clinical categories, which differed (p < 0.025) from the N category (87.9 +/- 5.5%; 12.05 months). The survival probabilities after 5 years of entering the A, B and C categories were 84.8 +/- 10.7%, 60.5 +/- 19.8% and 14.8 +/- 13.5%, respectively (p < 0.001). Immunological category 3 had lower transition probabilities and longer sojourn-times (58.8 +/- 16.6%; 53.3 months) than categories 1 (71.3 +/- 8.1%; 33.2 months) and 2 (75.6 +/- 10.5%; 19.8 months) (p < 0.01). The transition probabilities to C3 for states N3, A3 or B3 were 52.5 +/- 13.5%. In conclusion, the classification fits the clinical history better than the immunological history.

Degenerate four-wave mixing from laser-populated excited states

Degenerate four-wave mixing (DFWM) from laser-populated excited states, i.e., two-step DFWM (2S-DFWM), has been performed to investigate the possibility of increasing signal quality (i.e., strength or signal-to-noise ratio) when species with low transition probabilities or far-UV transitions are to be detected or when large beam areas are used. Gold atoms, aspirated into an air-acetylene flame, were chosen as a suitable species for this investigation. The 2S-DFWM signal strength was found to be comparable to the ordinary (one-step) DFWM signals for moderately high UV-light intensities but substantially better for low UV-light intensities. This finding implies that DFWM detection of species with lower transition probabilities in the first step as compared with gold (<10(-8) s(-1)) can benefit from the 2S-DFWM technique when moderate or low UV-light intensities are available. Additional possible advantages of using 2S-DFWM are also discussed.

A Demographic Study of Two Populations of the Seaweed Ascophyllum Nodosum

Very little is known about the demography in size—structured seaweed populations, and this is especially true for populations in variable environments. Thus, the demography of the brown alga Ascophyllum nodosum was analyzed with a matrix population model. This was built on a 3—yr study in two populations on the Swedish west coast, where &gt;1100 individuals were marked and followed twice each year. The environmental variability is due to the presence of ice during some of the winters. The frequency of ice years in the study area is known, and is higher at one site compared to the other. During the study there were 2 yr with ice and one without at both sites, and these temporal changes in the environment resulted in large variations in the vital rates of A. nodosum. The individuals were divided into five size classes and the population dynamics at years without ice were characterized by low mortality rates and high transition probabilities for growth to larger sizes, while years with ice had high mortality rates and high transition probabilities for breakage to smaller sizes. Of the 25 possible transitions in the life cycle graph all except 2 had nonzero entries, which means that the adult life of A. nodosum individuals can be described as plastic growth between all five size classes. A crude estimate of the recruitment showed that both populations will increase in numbers in ice—free years, but will decrease in years with ice. The size—dependent fertility rate is probably subject to errors, and thus the survival matrices were scaled with a fertility function built on total reproductive biomass per individual, allowing analyses of the demography at different levels of the asymptotic growth rate @l1. One of the main differences between the populations was that the stable size distribution for survival matrices in ice—free years was dominated by size class 4 at one population but class 5 at the other. Thus, to achieve the same value of @l1 higher fertility rates were needed at the population dominated by class 4. Elasticity analysis of the transition matrices showed the same tend, although the main result from that analysis was that growth to larger sizes of remaining in the same class contributed more to @l1 than reproduction. This was valid for all levels of @l1 investigated.

Perturbative reactive scattering within a quasiadiabatic representation: Multichannel application

Low energy reactive transition probabilities for a model multichannel collision problem, are determined within a so-called quasiadiabatic (QA) representation of the system electronic energy. The procedure involves setting up a set of coupled nonreactive surfaces (the QA representation) and then perturbatively mixing coupled-channel wave functions on the QA surfaces. It is applied to a hard-sphere-type model of the collinear A+BC reaction and for a relatively high system mass (5.0×104 a.u.). Optimization of the representation (which we have previously argued should temper maximization of the QA reactivity with a drive for balance between its diabatic and nonadiabatic components) yields results which are in very good agreement with exact ones (errors &amp;lt;10%) over a wide range of collision energies. At the same time, as the collision energy approaches the classical reactive threshold, we see evidence of QA failure; we trace this to difficulties with our particular optimization procedure when the diabatic contribution becomes dominant. ‘‘Conventional’’ perturbative results are generated for the same model problem and found to be poor in general (errors ≂40%–50%). It is demonstrated that the ineffectiveness of the conventional approach may be ascribed to the system’s high mass.

Influence of the pair distribution function on the site dependence of donor properties in ZnSe.

We used a more accurate pair distribution function---the nearest--available-neighbor one---to reanalyze previous work on the relative luminescence transition probabilities of donors in ZnSe. Earlier work with the nearest-neighbor distribution had shown that these relative transition probabilities differed by orders of magnitude between interstitial (alkali-metal) donors and substitutional (group-III) donors. At low concentration the results are practically unchanged. For high concentration, the relative results now show even larger differences. We conclude again that the interstitial (alkali-metal) donors have a substantially lower transition probability than the group-III donors in ZnSe.

On the parity of the yrast 8+ level in138Ce and an anomaly in theB(E2) values

On the basis of conversion electron andγ-angular distribution measurements new spin and parity assignments in138Ce have been made. They lead together with the already known lifetime of the 10+ yrast state whose parity was unclear to an extremely low transition probability of the 10+→8+ transition. A comparison with neighbouring even isotopes is made.

Theoretical studies of reactions in a laser field: F( 2P 3/2, 2P 1/2) + H 2+ ħω (0.469 eV)

The collinear F( 2P 3/2, 2P 1/2) + H 2 system in a strong laser field is studied employing the trajectory-surface-hopping method. The results are compared with a recent quantal study by Zimmerman, Baer and George. The two treatments yield low electronic non-adiabatic transition probabilities (⩽0.1). Good agreement is found in the high-energy region.