942 research outputs found
Macrophage response to Mycobacterium tuberculosis infection
No full textThe immune response to Mycobacteriumtuberculosis (Mtb) infection is the formation of multicellular lesions, or granolomas, in the lung of the individual. However, the structure of the granulomas and the spatial distribution of the immune cells within is not well understood. In this paper we develop a mathematical model investigating the early and initial immune response to Mtb. The model consists of coupled reaction-diffusion-advection partial differential equations governing the dynamics of the relevant macrophage and bacteria populations and a bacteria-produced chemokine. Our novel application of mathematical concepts of internal states and internal velocity allows us to begin to study this unique immunological structure. Volume changes resulting from proliferation and death terms generate a velocity field by which all cells are transported within the forming granuloma. We present numerical results for two distinct infection outcomes: controlled and uncontrolled granuloma growth. Using a simplified model we are able to analytically determine conditions under which the bacteria population decreases, representing early clearance of infection, or grows, representing the initial stages of granuloma formation.</p
The duration of intrauterine development influences discrimination of speech prosody in infants
No full textAuditory speech discrimination is essential for normal language development. Children born preterm are at greater risk of language developmental delays. Using functional near-infrared spectroscopy at term-equivalent age, the present study investigated early discrimination of speech prosody in 62 neonates born between week 23 and 41 of gestational age (GA). We found a significant positive correlation between GA at birth and neural discrimination of forward versus backward speech at term-equivalent age. Cluster analysis identified a critical threshold at around week 32 of GA, pointing out the existence of subgroups. Infants born before week 32 of GA exhibited a significantly different pattern of hemodynamic response to speech stimuli compared to infants born at or after week 32 of GA. Thus, children born before the GA of 32 weeks are especially vulnerable to early speech discrimination deficits. To support their early language development, we therefore suggest a close follow-up and additional speech and language therapy especially in the group of children born before week 32 of GA
Intermittency in solutions of the three-dimensional Navier-Stokes equations
No full textPublished versio
Dreams versus reality: Plenary debate session on quantum computing
No full text"First published in abridged form in Quantum Information Processing, 2 2003, pp. 449-472. Also, in its extended form this debate was first published as a chapter in the book Quantum Aspects of Life, Eds. D. Abbott, P. C. W. Davies, and A. Pati, Publ. Imperial College Press, London, 2008."Derek Abbott, Charles R. Doering, Carlton M. Caves, Daniel M. Lidar, Howard E. Brandt, Alex R. Hamilton, David K. Ferry, Julio Gea-Banacloche, Sergey M. Bezrukov and Laszlo B. Kis
Sex differences in neural processing of speech in neonates
No full textThe large majority of studies shows that girls develop their language skills faster than boys in the first few years of life. Are girls born with this advantage in language development? The present study used fNIRS in neonates to investigate sex differences in neural pro-cessing of speech within the first days of life. We found that speech stimuli elicited significantly more brain activity than non-speech stimuli in both groups of male and fe-male neonates. However, whereas girls showed significant HbO changes to speech stimuli only within the left hemisphere, boys exhibited simultaneous neural activations in both hemispheres, with a larger and more significant fronto-temporal cluster in the right hemisphere. Furthermore, in boys, the variation in time-to-peak latencies was consider-ably greater than in girls. These findings suggest an earlier maturation of language-related brain areas in girls and highlight the importance of sex-specific investigations of neural language networks in infants.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Intermittency and regularity issues in 3D Navier-Stokes turbulence
No full textTwo related open problems in the theory of 3 D Navier-Stokes turbulence are discussed in this paper. The first is the phenomenon of intermittency in the dissipation field. Dissipation-range intermittency was first discovered experimentally by Batchelor and Townsend over fifty years ago. It is characterized by spatio-temporal binary behaviour in which long, quiescent periods in the velocity signal are interrupted by short, active ‘events’ during which there are violent fluctuations away from the average. The second and related problem is whether solutions of the 3 D Navier-Stokes equations develop finite time singularities during these events. This paper shows that Leray’s weak solutions of the three-dimensional incompressible Navier-Stokes equations can have a binary character in time. The time-axis is split into ‘good’ and ‘bad’ intervals: on the ‘good’ intervals solutions are bounded and regular, whereas singularities are still possible within the ‘bad’ intervals. An estimate for the width of the latter is very small and decreases with increasing Reynolds number. It also decreases relative to the lengths of the good intervals as the Reynolds number increases. Within these ‘bad’ intervals, lower bounds on the local energy dissipation rate and other quantities, such as || u (·, t )|| ∞ and ||∇ u (·, t )|| ∞ , are very large, resulting in strong dynamics at sub-Kolmogorov scales. Intersections of bad intervals for n ≧1 are related to the potentially singular set in time. It is also proved that the Navier-Stokes equations are conditionally regular provided, in a given ‘bad’ interval, the energy has a lower bound that is decaying exponentially in time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46170/1/205_2005_Article_382.pd
lnternalizing problems in childhood and adolescence: predictive, etiological, and neurodevelopmental aspects
No full textInternalizing disorders such as anxiety and depressive disorders are common mental
disorders in childhood and adolescence. They are characterized by disordered
emotions and moods, causing emotional distress and impairment. The overarching aim
of the thesis is to investigate the relationship between internalizing problems and
adverse outcomes in late adolescence/early adulthood, and between internalizing
problems at different ages (i.e., childhood vs. adolescence), while taking various
neurodevelopmental disorders (NDDs) into account. All studies are based on the Child
and Adolescent Twin Study in Sweden, which uses self- and/or parent-reported survey
data, clinical diagnoses from the Swedish National Patient Register, and educational
data from the National School Register. Study I examines the relationship between
anxiety at age 15 and psychiatric outcomes in late adolescence/early adulthood. The
results show that adolescent anxiety predicted a variety of psychiatric outcomes,
even when adjusting for NDDs. Study II describes the relationship between
internalizing problems at age 15 and educational achievement in late adolescence/
early adulthood in a genetically sensitive design. Internalizing problems were found
to be negatively associated with educational achievement. Additive genetics
accounted for the largest part of the covariation between internalizing problems and
educational outcomes, with roughly one half of unique genetic effects being due to
internalizing problems and one half due to NDDs. Study III assesses the extent to
which internalizing symptoms at age 15 can be explained by symptoms of anxiety,
depression, and NDDs at age 9. The results showed that, overall, a small
proportion of internalizing symptoms in adolescence can be explained by
anxiety, depression, and NDDs in childhood. Study IV examines different
occurrences of NDDs in individuals with anxiety/depression at age 9 versus age 15.
Compared to individuals without anxiety/depression, those with childhood-onset
anxiety/depression had a substantially higher prevalence of NDD screening
diagnoses than did individuals with adolescent-onset. In conclusion,
internalizing problems in adolescence can predict a plethora of psychiatric
outcomes and educational underachievement, and they share etiological
influences with the latter, independently of NDDs. Childhood and adolescent
internalizing problems possibly represent different constructs and are differentially
related to NDDs. Future studies investigating treatment approaches and the etiology
of internalizing problems may benefit from taking age-of-onset into account
Data from: Distribution of label spacings for genome mapping in nanochannels
No full textÖdman, Daniel; Werner, Erik; Dorfman, Kevin D; Doering, Charles M; Mehlig, Bernhard. (2018). Data from: Distribution of label spacings for genome mapping in nanochannels. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/198066
Epitaxial growth of GaN/Ga2O3 and Ga2O3/GaN heterostructures for novel high electron mobility transistors
No full textHeterostructures made of GaN and ε-Ga2O3 epitaxial layers may be very interesting because they could exploit the high electron mobility of GaN combined with the ferroelectric character of ε-Ga2O3. We have explored the possibility of using ε-Ga2O3 templates, deposited by metalorganic chemical vapor deposition on sapphire substrates, in order to reduce the lattice mismatch of GaN with sapphire. Considering that ε-Ga2O3 is metastable and undergoes a first phase transition at around 700 °C, the GaN layers were deposited at two different temperatures (690 °C, 1050 °C). Preliminary electrical and SIMS investigations have evidenced the diffusion of oxygen from the ε-Ga2O3 to the GaN epitaxial layer, which results in an n-type conductivity and a sheet resistance as low as 70 Ohm/sq in a 1 μm thick GaN layer. The rocking curve of the GaN layers grown ε-Ga2O3/sapphire at standard high temperature (1050 °C) indicates a crystal quality worse than for GaN deposited directly on sapphire. In parallel, we studied the nucleation of ε-Ga2O3 on GaN templates. We evidenced that ε-Ga2O3 nucleates in 3D islands on the surface of GaN grown on on-axis sapphire, with coalescence taking place as the layer grows thicker. The use of off-cut sapphire substrates, instead, permits to inhibit islands formation, resulting in a smoother layer. The possibility of obtaining uniform and very thin ε-Ga2O3 layers on GaN layers opens interesting possibilities for the development of novel high electron mobility transistors (HEMT)
A Longitudinal Study to Characterize the Distribution Patterns of Mycobacterium avium ssp paratuberculosis in Semen, Blood and Faeces of a Naturally Infected Bull by IS 900 Semi-Nested and Quantitative Real-Time PCR
No full textJohne's disease is caused by Mycobacterium avium ssp. paratuberculosis (MAP) and has been recognized as an important bacterial infection in ruminants. Although MAP has been detected in semen and within the reproductive organs of bulls, the bacterial distribution and shedding patterns are currently not well characterized. Our investigation was performed to detect and quantify MAP in faeces, semen and blood samples repeatedly drawn from a naturally infected but asymptomatic 18-month-old German Simmental breeding bull candidate over a period of 3years (June 2007November 2010). Qualitative and quantitative polymerase chain reaction (PCR) techniques were used to correlate the presence and matrix-specific amounts of MAP. In total, 65 sampling dates were selected. Mycobacterium avium ssp. paratuberculosis was detected intermittently in all matrices with MAP-free intervals of up to 18weeks by an IS900 semi-nested PCR. The number of MAP-positive results from semen and blood samples was higher than from faecal samples. A quantitative polymerase chain reaction detected the highest MAP contents in faeces (103106MAP/g), while lower amounts were found in semen and blood samples (102105MAP/ml). Although no significant agreement was calculated between the presence of MAP in faeces and blood, a statistically significant positive correlation between its occurrence in semen and blood was determined (r=0.38, P<0.05, n=29). The present study contributes to a more detailed understanding of MAP distribution patterns in faeces, semen and blood of a subclinically infected breeding bull candidate. It highlights the possible role of breeding bulls as a source of MAP transmission and indicates the need for further monitoring and hygienic measures to prevent the spread of the infection via semen.Federal Ministry of Economics and Technology [KF2484201AJ9
- …
