765 research outputs found
A Solvable Sequence Evolution Model and Genomic Correlations
We study a minimal model for genome evolution whose elementary processes are
single site mutation, duplication and deletion of sequence regions and
insertion of random segments. These processes are found to generate long-range
correlations in the composition of letters as long as the sequence length is
growing, i.e., the combined rates of duplications and insertions are higher
than the deletion rate. For constant sequence length, on the other hand, all
initial correlations decay exponentially. These results are obtained
analytically and by simulations. They are compared with the long-range
correlations observed in genomic DNA, and the implications for genome evolution
are discussed.Comment: 4 pages, 4 figure
Correlation between magnetic interactions and domain structure in A1 FePt ferromagnetic thin films
We have investigated the relationship between the domain structure and the
magnetic interactions in a series of FePt ferromagnetic thin films of varying
thickness. As-made films grow in the magnetically soft and chemically
disordered A1 phase that may have two distinct domain structures. Above a
critical thickness nm the presence of an out of plane
anisotropy induces the formation of stripes, while for planar
domains occur.
Magnetic interactions have been characterized using the well known DCD-IRM
remanence protocols, plots, and magnetic viscosity measurements. We
have observed a strong correlation between the domain configuration and the
sign of the magnetic interactions. Planar domains are associated with positive
exchange-like interactions, while stripe domains have a strong negative
dipolar-like contribution. In this last case we have found a close correlation
between the interaction parameter and the surface dipolar energy of the stripe
domain structure. Using time dependent magnetic viscosity measurements, we have
also estimated an average activation volume for magnetic reversal, nm which is approximately
independent of the film thickness or the stripe period.Comment: 25 pages, 11 figure
Evaluation of Theoretical Frameworks to Detect Correlates of HPV Vaccination in the Midwest, US, Using Structural Equation Modeling
Knowledge of a valid, well-designed, and targeted theory-based framework helps better characterize reasons for HPV vaccine hesitancy and identify promising approaches to increase vaccination rates for eligible individuals. This study evaluated health theories in explaining factors affecting HPV vaccination and used a theoretical framework to identify direct and indirect predictors and mediators of HPV vaccination. A cross-sectional survey regarding HPV vaccine uptake and related factors was conducted among 1306 teenagers and young adults in the Midwest, US, in March and April 2023. Structural equation modeling confirmed fit of the framework based on the Integrated Health Theory (IHT) to the HPV vaccine data (Comparative Fit Index = 0.93; Tucker-Lewis Index = 0.92; Root Mean Square Error of Approximation = 0.053). While willingness to uptake the HPV vaccine directly predicted increased uptake (p \u3c 0.001), perceived benefits (p \u3c 0.001) and barriers (p \u3c 0.023) about the vaccine indirectly predicted increased and decreased uptake, respectively. In turn, beliefs about susceptibility (p = 0.005) and severity (p \u3c 0.001) of HPV infection and associated cancers and barriers to vaccination in general (p \u3c 0.001) indirectly predicted willingness to uptake the vaccine. In conclusion, IHT can be appropriate in examining predictors of HPV vaccine uptake in teenagers and young adults in the US, particularly in the Midwest
Millikelvin magnetic relaxation measurements of alpha-Fe2O3 antiferromagnetic particles
In this paper we report magnetic relaxation data for antiferromagnetic
alpha-Fe2O3 particles of 5 nm mean diameter in the temperature range 0.1 K to
25 K. The average spin value of these particles S=124 and the uniaxial
anisotropy constant D=1.6x10^-2 K have been estimated from the experimental
values of the blocking temperature and anisotropy field. The observed plateau
in the magnetic viscosity from 3 K down to 100 mK agrees with the occurrence of
spin tunneling from the ground state Sz = S. However, the scaling M vs Tln(nu
t) is broken below 5 K, suggesting the occurrence of tunneling from excited
states below this temperature.Comment: 4 pages (two columns), 4 figure
Global environmental changes: setting priorities for Latin American coastal habitats.
The definitive version is available at www.blackwell-synergy.comThe Intergovernmental Panel for Climate Change (IPCC) reports that Global Environmental Changes (GEC) are occurring quicker than at any other time over the last 25 million years and impacting upon marine environments (Bellard et al., 2012). There is overwhelming evidence showing that GEC are affecting both the quality and quantity of the goods and services provided by a wide range of marine ecosystems. In order to discuss regional preparedness for global environmental changes, a workshop was held in Ilhabela, Brazil (22- 26 April 2012) entitled "Evaluating the Sensitivity of Central and South American Benthic Communities to Global Environmental Changes" that drew together scientists from ten Latin American and three European countries. © 2013 Blackwell Publishing Ltd
Analysis of radiation-induced cell death in head and neck squamous cell carcinoma and rat liver maintained in microfluidic devices
Objective The aim of this study was to investigate how head and neck squamous cell carcinoma (HNSCC) tissue biopsies maintained in a pseudo in vivo environment within a bespoke microfluidic device respond to radiation treatment. Study Design Feasibility study. Setting Tertiary referral center. Subjects and Methods Thirty-five patients with HNSCC were recruited, and liver tissue from 5 Wistar rats was obtained. A microfluidic device was used to maintain the tissue biopsy samples in a viable state. Rat liver was used to optimize the methodology. HNSCC was obtained from patients with T1-T3 laryngeal or oropharyngeal SCC; N1-N2 metastatic cervical lymph nodes were also obtained. Irradiation consisted of single doses of between 2 Gy and 40 Gy and a fractionated course of 5×2 Gy. Cell death was assessed in the tissue effluent using the soluble markers lactate dehydrogenase (LDH) and cytochrome c and in the tissue by immunohistochemical detection of cleaved cytokeratin18 (M30 antibody). Results A significant surge in LDH release was demonstrated in the rat liver after a single dose of 20 Gy; in HNSCC, it was seen after 40 Gy compared with the control. There was no significant difference in cytochrome c release after 5 Gy or 10 Gy. M30 demonstrated a dose-dependent increase in apoptotic index for a given increase in single-dose radiotherapy. There was a significant increase in apoptotic index between 1×2 Gy and 5×2 Gy. Conclusion M30 is a superior method compared with soluble markers in detecting low-dose radiation-induced cell death. This microfluidic technique can be used to assess radiation-induced cell death in HNSCC and therefore has the potential to be used to predict radiation response
A new approach for the treatment of CLL using chlorambucil/hydroxychloroquine-loaded anti-CD20 nanoparticles
Current approaches for the treatment of chronic lymphocytic leukemia (CLL) have greatly improved the prognosis for survival, but some patients remain refractive to these therapeutic regimens. Hence, in addition to reducing the long-term sideeffects of therapeutics for all leukemia patients, there is an urgent need for novel therapeutic strategies for difficult-to-treat leukemia cases. Due to the cytotoxicity of drugs, the major challenge currently is to deliver the therapeutic agents to neoplastic cells while preserving the viability of non-malignant cells. In this study, we propose a therapeutic approach in which high doses of hydroxychloroquine and chlorambucil were loaded into biodegradable polymeric nanoparticles coated with an anti-CD20 antibody.We first demonstrated the ability of the nanoparticles to target and internalize in tumor B-cells. Moreover, these nanoparticles could kill not only p53-mutated/deleted leukemia cells expressing a low amount of CD20, but also circulating primary cells isolated from chronic lymphocytic leukemia patients. The safety of these nanoparticles was also demonstrated in healthy mice, and their therapeutic effects were shown in a new model of aggressive leukemia. These results showed that anti-CD20 nanoparticles containing hydroxychloroquine and chlorambucil can be effective in controlling aggressive leukemia and provided a rationale for adopting this approach for the treatment of other B-cell disorders. [Figure not available: see fulltext.
Chitosan as Source for Pesticide Formulations
Late blight and wilt caused by the oomycete, Phytophthora infestans, and the fungus, Fusarium solani f. sp. eumartii, respectively, are severe diseases in Solanaceae crops worldwide. Although traditional approaches to control plant diseases have mainly relied on toxic chemical compounds, current studies are focused to identify more sustainable options. Finding alternatives, a low molecular weight chitosan (LMWCh) obtained from biomass of Argentine Sea’s crustaceans was assayed. In an attempt to characterize the action of LMWCh alone or in combination with the synthetic fungicide Mancozeb, the antimicrobial properties of LMWCh were assayed. In a side-by-side comparison with the SYTOX Green nucleic acid stain and the nitric oxide–specific probe, diaminofluorescein-FM diacetate (DAF-FM DA), yielded a similar tendency, revealing LMWCh-mediated cell death. The efficacy of LMWCh, Mancozeb, and the mixture LMWCh–Mancozeb was in turn tested. A synergistic effect in the reduction of F. eumartii spore germination was measured in the presence of subinhibitory dosis of 0.025 mg ml−1 LMWCh and 0.008 mg ml−1 Mancozeb. This mixture was efficient to increase the effectiveness of the single treatments in protecting against biotic stress judged by a drastic reduction of lesion area in P. infestans–inoculated tissues and activation of the potato defense responses
Interacción de un perro doméstico con una persona desconocida en un ambiente nuevo
The domestic dog is able to adapt to new environments by changing their behavior depending on the context. In this process, activation of the autonomic nervous system and the hypothalamic-pituitary-adrenal axis under the control of consciousness involved. The aim of this study was to evaluate the influence of the external environment (clinical practice) on the interaction of dog with an unknown man. This work was performed in a private clinical practice, for it were randomized 8 adults dogs, of both genders and different races who attended the clinic. Of these, only half knew the environment (population A), the other half unknown (population B). All were applied a communication test against an unknown person. They were shot 4 minutes with camcorder from an adjacent room of 9 m2 window. Then focal and continuous observation of each animal was performed, recording the following variables: eye contact (frequency), latency approach and stay near the unknown (in seconds). For statistical analysis t-test was applied to check the distribution of the means of the two populations (A and B). This test showed no significant difference (p ≥ 0.05) behavioral responses between the two groups (known versus unknown environment). However, there was a trend of more frequent eye contact with the person who did not know the environment (mean = 6.00), compared with those who did know him (mean = 1.75) (p = 0.09), probably trying to start inter-specific communication faster with the human in a novel environment. When dogs attend the clinic as patients consulting for the first time, the office environment is totally unknown: smells, sights, other dogs and people. In this unfamiliar environment, it is with human beings with whom he develops eye contact and touch to keep your sensory homeostasis, and thus achieve a balance back into behavioral homeostasis.El perro domestico es capaz de adaptarse a nuevos ambientes modificando su comportamiento según el contexto. El sistema nervioso autónomo y el eje hipotálamo-pituitario-adrenal interpretan la información sensorial y la transforman en actividad muscular. El objetivo del trabajo fue evaluar la influencia del ambiente (consultorio) sobre la interacción del perro con una persona desconocida. Se utilizaron 8 perros adultos, de ambos sexos y diferentes razas. La mitad de ellos conocía el ambiente (población A) y la otra mitad lo desconocía (población B). Una persona desconocida les impuso a todos un test de comunicación en una habitación de 9 m2 . Con una videocámara se filmaron 4 minutos desde una ventana. En cada animal se registraron las siguientes variables: contacto visual (frecuencia), latencia en aproximación y permanencia cerca del desconocido (en segundos). Estadísticamente se aplicó la prueba T para comprobar la distribución de las medias de las dos poblaciones (A y B), la cual no mostró diferencias significativas (p≥0,05) en las respuestas conductuales entre ambos grupos (ambiente conocido versus desconocido). No obstante, la tendencia de contacto visual con la persona fue mayor en los perros que ignoraban el ambiente versus aquéllos que lo conocían, probablemente intentando una más rápida comunicación con las personas. En el caso particular de los perros, el primer adulto regulador de la homeostasia conductual es la madre, pero en los perros que conviven en comunidades urbanas es el ser humano. Cuando los perros asisten a la consulta clínica como pacientes por primera vez, el ambiente del consultorio es totalmente desconocido: olores, imágenes, otros perros y personas. En ese ambiente desconocido, es con el ser humano con quien entabla contacto visual y táctil para mantener su homeostasis sensorial y de esa manera alcanzar nuevamente un equilibrio en su homeostasis conductual
Magnetoresistance in FeGa thin films presenting striped magnetic pattern: the role of closure domains and domain walls
In this work we show the existence of closure domains in FeGa
thin films featuring a striped magnetic pattern and study the effect of the
magnetic domain arrangement on the magnetotransport properties. By means of
X-ray resonant magnetic scattering, we experimentally demonstrate the presence
of such closure domains and estimate their sizes and relative contribution to
surface magnetization. Magnetotransport experiments show that the behavior of
the magnetoresistance depends on the measurement geometry as well as on the
temperature. When the electric current ows perpendicular to the stripe
direction, the resistivity decreases when a magnetic field is applied along the
stripe direction (negative magnetoresistance) in all the studied temperature
range, and the calculations indicate that the main source is the anisotropic
magnetoresistance. In the case of current flowing parallel to the stripe
domains, the magnetoresistance changes sign, being positive at room temperature
and negative at 100 K. To explain this behavior, the contribution to
magnetoresistance from the domain walls must be considered besides the
anisotropic one.Comment: 8 pages, 5 figure
- …