331 research outputs found
Discovery of a single faint AGN in a large sample of z > 5 Lyman break galaxies
No full textAs part of a large spectroscopic survey of z > 5 Lyman break galaxies (LBGs), we have identified a single source which is clearly hosting an active galactic nucleus (AGN). Out of a sample of more than 50 spectroscopically confirmed R-band dropout galaxies at z∼ 5 and above, only J104048.6−115550.2 at z= 5.44 shows evidence for a high ionization potential emission line indicating the presence of a hard ionizing continuum from an AGN. Like most objects in our sample the rest-frame-UV spectrum shows the UV continuum breaking across a Lyα line. Uniquely within this sample of LBGs, emission from N V is also detected, a clear signature of AGN photoionization. The object is spatially resolved in Hubble Space Telescope (HST) imaging. This, and the comparatively high Lyα/N V flux ratio indicates that the majority of the Lyα (and the UV continuum longward of it) originates from stellar photoionization, a product of the ongoing starburst in the LBG. Even without the AGN emission, this object would have been photometrically selected and spectroscopically confirmed as a Lyman break in our survey. The measured optical flux (IAB= 26.1) is therefore an upper limit to that from the AGN and is of order 100 times fainter than the majority of known quasars at these redshifts. The detection of a single object in our survey volume is consistent with the best current models of high redshift AGN luminosity function, providing a substantial fraction of such AGN is found within luminous starbursting galaxies. We discuss the cosmological implications of this discovery
Optimizing experimental parameters for tracking of diffusing particles
No full textInternational audienceWe describe how a single-particle tracking experiment should be designed in order for its recorded trajectories to contain the most information about a tracked particle's diffusion coefficient. The precision of estimators for the diffusion coefficient is affected by motion blur, limited photon statistics, and the length of recorded time series. We demonstrate for a particle undergoing free diffusion that precision is negligibly affected by motion blur in typical experiments, while optimizing photon counts and the number of recorded frames is the key to precision. Building on these results, we describe for a wide range of experimental scenarios how to choose experimental parameters in order to optimize the precision. Generally, one should choose quantity over quality: experiments should be designed to maximize the number of frames recorded in a time series, even if this means lower information content in individual frames
The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray source
No full textWe present an analysis of the extreme obscuration variability observed during an XMM–Newton 5-d continuous monitoring of the active galactic nuclei (AGN) in NGC 1365. The source was in a reflection-dominated state in the first ∼1.5 d, then a strong increase in the 7–10 keV emission was observed in ∼10 h, followed by a symmetric decrease. The spectral analysis of the different states clearly shows that this variation is due to an uncovering of the X-ray source. From this observation, we estimate a size of the X-ray source DS < 1013 cm, a distance of the obscuring clouds R∼ 1016 cm and a density n∼ 1011 cm−3. These values suggest that the X-ray absorption/reflection originates from the broad-line region clouds. This is also supported by the resolved width of the iron narrow Kα emission line, consistent with the width of the broad Hβ line
Example of how the temporal Gillespie algorithm works for an SIR process on a time-varying network.
No full text<p>We consider the time-varying network of <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004579#pcbi.1004579.g001" target="_blank">Fig 1A</a> (Network)—time evolves along the vertical axis; a rejection sampling algorithm considers each transition process at each time-step individually (Transitions); the temporal Gillespie algorithm considers the integrated cumulative transition rate of all transition processes, <math><mrow><mi>L</mi><mo>(</mo><mi>t</mi><mo>;</mo><mn>0</mn><mo>)</mo></mrow></math>, and compares it with the random normalized waiting times <math><msubsup><mi>τ</mi><mi>l</mi><mo>′</mo></msubsup></math> (Normalized time). A transition takes place whenever <math><mrow><mi>L</mi><mrow><mo>(</mo><mi>t</mi><mo>;</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><msubsup><mo>∑</mo><mrow><mi>l</mi><mo>=</mo><mn>0</mn></mrow><mi>q</mi></msubsup><msubsup><mi>τ</mi><mi>l</mi><mo>′</mo></msubsup></mrow></math> for any <math><mrow><mi>q</mi><mo>∈</mo><mi>N</mi></mrow></math>. The temporal Gillespie algorithm works as follows. (A) The first normalized waiting time <math><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup></math> is drawn from an exponential distribution with unit rate [<math><mrow><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup><mo>∼</mo>Exp<mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow></math>] (Normalized time). From the state of the network at the first time-step, the set of possible transitions Ω(0) is found (Transitions), and from this the cumulative transition rate Λ(0) is calculated. The integrated cumulative transition rate, <math><mrow><mi>L</mi><mo>(</mo><mrow><mo>Δ</mo><mi>t</mi></mrow><mo>;</mo><mn>0</mn><mo>)</mo><mo>=</mo><mo>Λ</mo><mo>(</mo><mn>0</mn><mo>)</mo><mrow><mo>Δ</mo><mi>t</mi></mrow></mrow></math> is compared to <math><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup></math>. If, as in the present example, <math><mrow><mo>Λ</mo><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mrow><mo>Δ</mo><mi>t</mi></mrow><mo><</mo><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup></mrow></math> the algorithm is advanced to the next time-step. (B) and (C) The set of possible transitions Ω(<i>t</i><sub><i>n</i></sub>) and the cumulative transition rate Λ(<i>t</i><sub><i>n</i></sub>) is updated at each following time-step <i>n</i>; if <math><mrow><mi>L</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>n</mi></msub><mo>;</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><mrow><mo>Δ</mo><mi>t</mi></mrow><msubsup><mo>∑</mo><mrow><mi>l</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow></msubsup><mrow><mo>Λ</mo><mo>(</mo><msub><mi>t</mi><mi>l</mi></msub><mo>)</mo></mrow></mrow></math> is still smaller than <math><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup></math>, the algorithm is advanced to the next time-step. (D) During the first time-step <i>n</i>** where <math><mrow><mi>L</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>n</mi><mrow><mo>*</mo><mo>*</mo></mrow></msub><mo>;</mo><mn>0</mn><mo>)</mo></mrow><mo>≥</mo><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup></mrow></math>, a transition takes place. The exact time of this transition, <i>t</i>**, is given by <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004579#pcbi.1004579.e048" target="_blank">Eq (12)</a> and the transition <i>m</i> that takes place is chosen among the possible transitions in the given time-step with probability proportional to its transition rate λ<sub><i>m</i></sub> [Transitions and <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004579#pcbi.1004579.e042" target="_blank">Eq (10)</a>]. (E) The transition changes the system (Network) and consequently the set of possible transitions, Ω(<i>t</i>**), (Transitions); thus Ω(<i>t</i>**) and Λ(<i>t</i>**) must be updated, which in turn changes the remainder of <math><mrow><mi>L</mi><mo>(</mo><msub><mi>t</mi><mi>n</mi><mrow><mo>*</mo><mo>*</mo></mrow></msub><mo>;</mo><mn>0</mn><mo>)</mo></mrow></math> (Normalized time). A new normalized waiting time is then drawn, <math><mrow><msubsup><mi>τ</mi><mn>2</mn><mo>′</mo></msubsup><mo>∼</mo>Exp<mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow></math>; if <math><mrow><mi>L</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>n</mi><mrow><mo>*</mo><mo>*</mo></mrow></msub><mo>;</mo><mn>0</mn><mo>)</mo></mrow><mo><</mo><msubsup><mi>τ</mi><mn>1</mn><mo>′</mo></msubsup><mo>+</mo><msubsup><mi>τ</mi><mn>2</mn><mo>′</mo></msubsup></mrow></math>, no further transitions takes place during the time-step and the algorithm is advanced to the next time-step (note that multiple transitions may occur during the same time-step). (F) The above procedure is reiterated.</p
Gillespie algorithms for stochastic multiagent dynamics in populations and network
No full textMany multiagent dynamics, including various collective dynamics occurring on
networks, can be modeled as a stochastic process in which the agents in the
system change their state over time in interaction with each other. The
Gillespie algorithms are popular algorithms that exactly simulate such
stochastic multiagent dynamics when each state change is driven by a discrete
event, the dynamics is defined in continuous time, and the stochastic law of
event occurrence is governed by independent Poisson processes. In the first
main part of this volume, we provide a tutorial on the Gillespie algorithms
focusing on simulation of social multiagent dynamics occurring in populations
and networks. We do not assume advanced knowledge of mathematics (or computer
science or physics). We clarify why one should use the continuous-time models
and the Gillespie algorithms in many cases, instead of easier-to-understand
discrete-time models. In the remainder of this volume, we review recent
extensions of the Gillespie algorithms aiming to add more reality to the model
(i.e., non-Poissonian cases) or to speed up the simulations.Comment: 25 figures. Elements in the Structure and Dynamics of Complex
Networks. Cambridge: Cambridge University Press (2023
Risk factors and comorbidities of hand eczema in the Northern Finland Birth Cohort 1966
No full textAbstract
Hand eczema (HE) is a common inflammatory skin disease. It may occur across all age groups, with the highest incidence observed in women and young adults. The clinical presentation varies depending on the stage of the disease, with itching, pain, and burning sensations being common symptoms. HE often follows a recurrent and chronic course, significantly impacting quality of life and imposing substantial cost on society, particularly in occupational settings.
The aim of this thesis was to increase the knowledge of risk factors associated with HE as well as the psychological and somatic comorbidities in the general population.
For these purposes, data were collected through questionnaires as part of the Northern Finland Birth Cohort 1966 (NFBC1966) at the age of 46 years. Data from NFBC1966 have been collected since birth and supplemented with parental information.
In this study, atopic eczema (AD) was associated with more than a ninefold increased risk of HE, and other atopic conditions were also linked to an elevated risk. A parental history of AD or allergic rhinitis may likewise contribute to a heightened risk of HE. Additionally, obesity may increase the risk, whereas moderate and high levels of physical activity seem to have a protective effect against HE. Furthermore, HE was associated with symptoms of depression and anxiety, as well as heightened susceptibility to infections.
This study confirms atopic conditions beyond AD as significant risk factors for HE, although parental and lifestyle factors may have an effect. Clinicians should be aware of the potential presence of somatic and psychiatric comorbidities in patients with HE as these might affect the overall health and well-being of individuals with HE. Original papers Koskelo, M., Sinikumpu, S., Jokelainen, J., & Huilaja, L. (2022). Risk factors of hand eczema: A population‐based study among 900 subjects. Contact Dermatitis, 87(6), 485–491. https://doi.org/10.1111/cod.14205 https://doi.org/10.1111/cod.14205 Self-archived version Koskelo, M., Sinikumpu, S., Jokelainen, J., & Huilaja, L. (2023). Anxiety and depression in patients with hand eczema: A population‐based study among 853 middle‐aged subjects. Contact Dermatitis, 89(6), 464–470. https://doi.org/10.1111/cod.14412 https://doi.org/10.1111/cod.14412 Self-archived version Koskelo, M., Sinikumpu, S-P., Jokelainen, J., & Huilaja, L. (2025). The association between hand eczema and susceptibility to infections in Northern Finland: A retrospective cohort study. Manuscript submitted for publication. Tiivistelmä
Käsi-ihottuma on yksi tavallisimmista tulehduksellisista ihosairauksista. Sitä esiintyy yleisimmin naisilla ja nuorilla aikuisilla, mutta se on mahdollinen kaikissa ikäryhmissä. Käsi-ihottuman kliininen kuva vaihtelee taudin vaiheen mukaan. Sen tavallisimpia oireita ovat kutina, kipu ja polttelu. Käsi-ihottumalla on taipumus uusiutua ja kroonistua, mikä heikentää merkittävästi elämänlaatua ja aiheuttaa huomattavat yhteiskunnalliset kustannukset, erityisesti työperäisissä tilanteissa esiintyessään.
Tämän väitöskirjan tavoitteena oli lisätä tietoa käsi-ihottumaan liittyvistä riskitekijöistä sekä psyykkisistä ja somaattisista liitännäissairauksista väestötasolla.
Tutkimuksen aineistona käytettiin Pohjois-Suomen syntymäkohortin 1966 (NFBC1966) 46-vuotistutkimuksen aineistoa, joka sisälsi kliinisen tutkimuksen lisäksi laajat terveys- ja elämäntapakyselyt. Syntymäkohortin aineistoa on kerätty tutkittavien syntymästä lähtien, ja sitä on täydennetty vanhempien tiedoilla.
Tässä väitöstutkimuksessa todettiin, että atooppinen ihottuma lisäsi käsi-ihottuman riskiä yli yhdeksänkertaisesti, ja myös muut atooppiset sairaudet olivat yhteydessä kohonneeseen käsi-ihottuman riskiin. Myös vanhemman atooppinen ihottuma tai allerginen nuha voivat tämän tutkimuksen perusteella lisätä käsi-ihottuman ilmaantumisen riskiä. Elämäntapatekijöistä lihavuus voi olla sairastumisriskiä nostava tekijä, kun taas kohtuullinen tai runsas fyysinen aktiivisuus näyttäisi suojaavan käsi-ihottumalta. Lisäksi havaitsimme, että käsi-ihottuma oli yhteydessä myös masennus- ja ahdistusoireisiin sekä lisääntyneeseen infektioherkkyyteen.
Tutkimus osoitti, että myös muut atooppiset sairaudet kuin atooppinen ihottuma ovat merkittäviä käsi-ihottuman riskitekijöitä. Myös vanhempien atooppiset sairaudet ja tutkittavan elämäntavat saattavat vaikuttaa käsi-ihottuman kehittymisen riskiin. Kliinisessä työssä tulisi käsi-ihottumapotilaat arvioida kokonaisvaltaisesti huomioiden mahdollinen somaattinen ja psykiatrinen liitännäissairastavuus. Osajulkaisut Koskelo, M., Sinikumpu, S., Jokelainen, J., & Huilaja, L. (2022). Risk factors of hand eczema: A population‐based study among 900 subjects. Contact Dermatitis, 87(6), 485–491. https://doi.org/10.1111/cod.14205 https://doi.org/10.1111/cod.14205 Rinnakkaistallennettu versio Koskelo, M., Sinikumpu, S., Jokelainen, J., & Huilaja, L. (2023). Anxiety and depression in patients with hand eczema: A population‐based study among 853 middle‐aged subjects. Contact Dermatitis, 89(6), 464–470. https://doi.org/10.1111/cod.14412 https://doi.org/10.1111/cod.14412 Rinnakkaistallennettu versio Koskelo, M., Sinikumpu, S-P., Jokelainen, J., & Huilaja, L. (2025). The association between hand eczema and susceptibility to infections in Northern Finland: A retrospective cohort study. Manuscript submitted for publication. Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Health and Biosciences of the University of Oulu for public defence in Auditorium 8 of Oulu University Hospital, on 21 November 2025, at 12 noonAbstract
Hand eczema (HE) is a common inflammatory skin disease. It may occur across all age groups, with the highest incidence observed in women and young adults. The clinical presentation varies depending on the stage of the disease, with itching, pain, and burning sensations being common symptoms. HE often follows a recurrent and chronic course, significantly impacting quality of life and imposing substantial cost on society, particularly in occupational settings.
The aim of this thesis was to increase the knowledge of risk factors associated with HE as well as the psychological and somatic comorbidities in the general population.
For these purposes, data were collected through questionnaires as part of the Northern Finland Birth Cohort 1966 (NFBC1966) at the age of 46 years. Data from NFBC1966 have been collected since birth and supplemented with parental information.
In this study, atopic eczema (AD) was associated with more than a ninefold increased risk of HE, and other atopic conditions were also linked to an elevated risk. A parental history of AD or allergic rhinitis may likewise contribute to a heightened risk of HE. Additionally, obesity may increase the risk, whereas moderate and high levels of physical activity seem to have a protective effect against HE. Furthermore, HE was associated with symptoms of depression and anxiety, as well as heightened susceptibility to infections.
This study confirms atopic conditions beyond AD as significant risk factors for HE, although parental and lifestyle factors may have an effect. Clinicians should be aware of the potential presence of somatic and psychiatric comorbidities in patients with HE as these might affect the overall health and well-being of individuals with HE.Tiivistelmä
Käsi-ihottuma on yksi tavallisimmista tulehduksellisista ihosairauksista. Sitä esiintyy yleisimmin naisilla ja nuorilla aikuisilla, mutta se on mahdollinen kaikissa ikäryhmissä. Käsi-ihottuman kliininen kuva vaihtelee taudin vaiheen mukaan. Sen tavallisimpia oireita ovat kutina, kipu ja polttelu. Käsi-ihottumalla on taipumus uusiutua ja kroonistua, mikä heikentää merkittävästi elämänlaatua ja aiheuttaa huomattavat yhteiskunnalliset kustannukset, erityisesti työperäisissä tilanteissa esiintyessään.
Tämän väitöskirjan tavoitteena oli lisätä tietoa käsi-ihottumaan liittyvistä riskitekijöistä sekä psyykkisistä ja somaattisista liitännäissairauksista väestötasolla.
Tutkimuksen aineistona käytettiin Pohjois-Suomen syntymäkohortin 1966 (NFBC1966) 46-vuotistutkimuksen aineistoa, joka sisälsi kliinisen tutkimuksen lisäksi laajat terveys- ja elämäntapakyselyt. Syntymäkohortin aineistoa on kerätty tutkittavien syntymästä lähtien, ja sitä on täydennetty vanhempien tiedoilla.
Tässä väitöstutkimuksessa todettiin, että atooppinen ihottuma lisäsi käsi-ihottuman riskiä yli yhdeksänkertaisesti, ja myös muut atooppiset sairaudet olivat yhteydessä kohonneeseen käsi-ihottuman riskiin. Myös vanhemman atooppinen ihottuma tai allerginen nuha voivat tämän tutkimuksen perusteella lisätä käsi-ihottuman ilmaantumisen riskiä. Elämäntapatekijöistä lihavuus voi olla sairastumisriskiä nostava tekijä, kun taas kohtuullinen tai runsas fyysinen aktiivisuus näyttäisi suojaavan käsi-ihottumalta. Lisäksi havaitsimme, että käsi-ihottuma oli yhteydessä myös masennus- ja ahdistusoireisiin sekä lisääntyneeseen infektioherkkyyteen.
Tutkimus osoitti, että myös muut atooppiset sairaudet kuin atooppinen ihottuma ovat merkittäviä käsi-ihottuman riskitekijöitä. Myös vanhempien atooppiset sairaudet ja tutkittavan elämäntavat saattavat vaikuttaa käsi-ihottuman kehittymisen riskiin. Kliinisessä työssä tulisi käsi-ihottumapotilaat arvioida kokonaisvaltaisesti huomioiden mahdollinen somaattinen ja psykiatrinen liitännäissairastavuus
Single-particle trajectories reveal two-state diffusion-kinetics of hOGG1 proteins on DNA
No full textInternational audienceWe reanalyze trajectories of hOGG1 repair proteins diffusing on DNA. A previous analysis of these trajec-tories with the popular mean-squared-displacement approach revealed only simple diffusion. Here, a new optimal estimator of diffusion coefficients reveals two-state kinetics of the protein. A simple, solvable model, in which the protein randomly switches between a loosely bound, highly mobile state and a tightly bound, less mobile state is the simplest possible dynamic model consistent with the data. It yields accurate estimates of hOGG1's (i) diffusivity in each state, uncorrupted by experimental errors arising from shot noise, motion blur and thermal fluctuations of the DNA; (ii) rates of switching between states and (iii) rate of detachment from the DNA. The protein spends roughly equal time in each state. It detaches only from the loosely bound state, with a rate that depends on pH and the salt concentration in solution, while its rates for switching between states are insensitive to both. The diffusivity in the loosely bound state depends primarily on pH and is three to ten times higher than in the tightly bound state. We propose and discuss some new experiments that take full advantage of the new tools of analysis presented here
Temporal Gillespie algorithm: Fast simulation of contagion processes on time-varying networks
No full textInternational audienceStochastic simulations are one of the cornerstones of the analysis of dynamical processes on complex networks, and are often the only accessible way to explore their behavior. The development of fast algorithms is paramount to allow large-scale simulations. The Gillespie algorithm can be used for fast simulation of stochastic processes, and variants of it have been applied to simulate dynamical processes on static networks. However, its adaptation to temporal networks remains non-trivial. We here present a temporal Gillespie algorithm that solves this problem. Our method is applicable to general Poisson (constant-rate) processes on temporal networks, stochastically exact, and up to multiple orders of magnitude faster than traditional simulation schemes based on rejection sampling. We also show how it can be extended to simulate non-Markovian processes. The algorithm is easily applicable in practice, and as an illustration we detail how to simulate both Poissonian and non-Markovian models of epidemic spreading. Namely, we provide pseudocode and its implementation in C++ for simulating the paradigmatic Susceptible-Infected-Susceptible and Susceptible-Infected-Recovered models and a Susceptible-Infected-Recovered model with non-constant recovery rates. For empirical networks, the temporal Gillespie algorithm is here typically from 10 to 100 times faster than rejection sampling
The Effect of Chronic Hyponatremia on Bone Mineral Loss Evaluated by Retrospective National Danish Patient Data
No full textPURPOSE: To evaluate the effect of chronic mild hyponatremia ([Na+]=130-137mmol/L) on bone mineral content (BMC) and bone mineral density (BMD) loss through multiple, serial dual-energy X-ray absorptiometry (DXA) scans.METHODS: Utilizing biochemical and DXA scan data from two Danish regions between 2004 and 2011, supplemented with national Danish patient diagnosis and prescription reimbursement databases, a retrospective cohort study was performed. All subjects with more than one DXA scan were included, then stratified into "normonatremia" ([Na(+)]=[137.00-147.00] mmol/L) and "mild hyponatremia" ([Na(+)]=[130.00-137.00[mmol/L) based on mean and confidence interval (CI) values calculated from all plasma sodium measurements between each subject's first and last DXA scan. Baseline, follow-up and delta values for hip and lumbar spine BMC and BMD were estimated between groups, then adjusted for comorbidity and medication use.RESULTS: Hip and lumbar spine groups had 884 and 1069 patients with "normonatremia" versus 58 and 58 patients with "mild hyponatremia", respectively. Mild hyponatremia was associated with lower BMC and BMD in nearly all regions of the hip, and with worse losses in the trochanteric, femoral neck and total hip regions. Mild hyponatremia had limited effect on the lumbar spine.CONCLUSIONS: Chronic mild hyponatremia seems to greatly affect bone in the hip, while the effect is limited in the lumbar spine. We suggest further retrospective study of patients with moderate (P-Na=120-130mmol/L) to severe hyponatremia (P-Na<120mmol/L) and prospective studies to further examine the association.</p
Notation pertaining to the temporal Gillespie algorithm.
No full text<p>The row “First appearance(s)” points to where where the notation is introduced in the Results section.</p
- …
