2,893 research outputs found
Chemical Comparison of Two Ecotypes of Loblolly Pine (Pinus Taeda L.)
Loblolly pine from the continuous range in east Texas was compared with an apparently drought-resistant ecotype, the so-called "Lost pines" or "Bastrop pines." The Bastrop pines are found in a small area of central Texas isolated from the rest of the loblolly range, and in a region receiving considerably less rainfall. Determinations made were: holocellulose, alpha cellulose, ash, specific gravity, and percentages of earlywood and latewood. Nutrient analyses for levels of sodium, potassium, calcium, magnesium, zinc, manganese, and copper were also performed. It was found that the earlywood of the east Texas population had significantly greater levels of holocellulose and alpha cellulose. Regression analyses were performed relating the nutrient values to the chemical components. The appearance of potassium and magnesium in these equations, for the Bastrop pines, may indicate physiological adaptation to the more xeric environment
Amphibian peptides for skin protection and healing
BACKGROUND: Amphibians are currently suffering a dramatic decline worldwide, mainly due to chytridiomycosis, a skin infection caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). An important natural defense of amphibian skin is the production of antimicrobial peptides (AMPs) by granular glands in the dermis. AMPs collected from several species of frogs successfully inhibit the growth of Bd in vitro. Besides their anti-microbial and anti-fungal activities, AMPs have been shown to exert other biological effects such as anti-viral, anti-tumor, anti-oxidant, immunomodulating and wound healing.
AIM: We intended to test the efficacy of AMPs as cutaneous defenses in frog species either resistant or susceptible to Bd.
METHODS: 3 frog species (Gastrotheca nebulanastes (GN), G. excubitor (GE) and Hypsiboas gladiator (HG), were collected in montane scrub, cloud forest and high elevation grassland habitats near Manu National Park in southeastern Peru. AMP secretion was stimulated by injection of norepinephrine into the dorsal lymph sacks. AMPs were then purified by chromatographic techniques. The human endothelial cell line HECV was treated with AMP concentrations ranging from 0.005 to 50 \ub5g/mL. Cell viability was verified by MTT test. Wound healing properties were analyzed by scratch wound assay. AMP inhibition strength against Bd growth was measured in vitro by incubating Bd zoospores with different concentrations of AMPs.
RESULTS: Treatment with AMPs secreted from GN, GE and HG did not affect HECV cell viability at any concentration tested. No significant differences in cell migration rate were observed in HECV cells scratched and treated with GN and GE AMPs. Only HG peptides showed wound healing properties as well as strong Bd growth inhibiting ability.
CONCLUSIONS: Stimulation of wound healing mechanisms and inhibition of Bd growth by skin AMPs might both contribute to HG resistance to chytridiomycosis. Understanding the role of skin defenses may lead to the development of novel Bd mitigation strategies. Possible applications of amphibian AMPs in skin medicine deserve attention and further studies.
This work was funded by the European Commission (Tender ENV.B.3/SER/2016/0028, Mitigating a new infectious disease in salamanders to counteract the loss of European biodiversity) and by Parco Nazionale delle Cinque Terre
Role of Composite Materials in Aircraft Construction
Danas su u zrakoplovnim konstrukcijama sve više zastupljeni kompozitni materijali. U ovom završnom radu opisana je primjena polimernih kompozita u zrakoplovnoj industriji. Spomenute su i ostale vrste kompozita koji imaju značajnu ulogu u zrakoplovstvu. Obrađena je teorija samih kompozitnih materijala, preko vrsta, njihovog načina proizvodnje te primjena u industriji, uz poseban naglasak na polimerne kompozite ojačane vlaknima. Primjena kompozitnih materijala u zrakoplovnim konstrukcijama ističe se u raznim vrstama i kombinacijama. Svaka vrsta zasebno ima svoje prednosti i svojstva koja konkuriraju dosadašnjim konvencionalnim materijalima. U izradi strukturalnih elemenata zrakoplova kompozitni materijali omogućuju proizvodnju kompleksnih struktura i oblika, a zatim i vrlo visoke performanse tih elemenata. Upravo tim naprednim svojstvima hibridnih kompozitnih materijala omogućuje se razvoj i proizvodnja zrakoplova vrlo visokih performansi, male teţine, te samim tim učinkovitijih i sigurnijih zrakoplova. Buduća tehnologija proizvodnje kompozitnih materijala uz popraćenu standardizaciju pruţa automatizirane procese proizvodnje koji svojom tehnologijom smanjuju cijene izgradnje zrakoplova kompozitnih konstrukcija. Primjer primjene kompozitnih materijala na zrakoplovima Boeing 787 Dreamliner, Airbus 380 i Pipistrel Panthera obrađen je u ovom završnom radu.In recent years the big emphasize in making the aircraft construction is put on a composite materials. The use of newest polymer composite in airplane industry are discribed in this final paper. Furthermore, the composite materials are introduced and explained. Different types, method of manufacture and application is explained more closely with the particular emphasis on polymer composites reinforced with fibers. The composite materials in airplane industry can be used in many ways and in many different combinations. Each type has its own advantages and features that compete with the conventional materials. In making the structural elements of the aircraft composite materials enable the production of complex structures and forms which in a same time allows very high performance of the new materials. Because of these advanced properties of hybrid composite materials the development and production of the aircraft high performance is possible. The main features that are improved are decreased weight of the aircraft , therefore they has better safety of the aircraft. Future manufacturing technology of composite materials with standardization provides automated processes that reduces the cost of building an aircraft composite structures.In this final paper the application of composite materials on aircraft Boeing 787 Dreamliner, Airbus A380 and Pipistrel Panthera is closely explained
Protohistoric briquetage at Puntone (Tuscany, Italy):principles and processes of an industry based on the leaching of saline lagoonal sediments
A protohistoric (c.10th-5th c. BC) briquetage site at Puntone (Tuscany, Italy) was studied to unravel the salt production processes and materials involved. Geophysical surveys were used to identify kilns, pits, and dumps. One of these pits and a dump were excavated, followed by detailed chemical and physical analyses of the materials encountered. The pit had been used for holding brine, obtained by leaching of lagoonal sediment over a sieve, that afterwards was discarded to form large dumps. Phases distinguished indicate that the pit filled with fine sediment and was regularly "cleaned." The presence of ferroan-magnesian calcite in the pit fill testifies to the prolonged presence of anoxic brine. The production processes could be reconstructed in detail by confronting the analytical results with known changes in composition of a brine upon evaporation. These pertain in particular to the accumulation of "bitterns" and increased B (boron) concentrations in a residual brine. Both could be traced in the materials studied, and were found to be far more indicative than the ubiquitously studied concentrations of Cl and Na.</p
Protohistoric briquetage at Puntone (Tuscany, Italy) : principles and processes of an industry based on the leaching of saline lagoonal sediments
A protohistoric (c.10th–5th c. BC) briquetage site at Puntone (Tuscany, Italy) was studied to unravel the salt production processes and materials involved. Geophysical surveys were used to identify kilns, pits, and dumps. One of these pits and a dump were excavated, followed by detailed chemical and physical analyses of the materials encountered. The pit had been used for holding brine, obtained by leaching of lagoonal sediment over a sieve, that afterwards was discarded to form large dumps. Phases distinguished indicate that the pit filled with fine sediment and was regularly “cleaned.” The presence of ferroan‐magnesian calcite in the pit fill testifies to the prolonged presence of anoxic brine. The production processes could be reconstructed in detail by confronting the analytical results with known changes in composition of a brine upon evaporation. These pertain in particular to the accumulation of “bitterns” and increased B (boron) concentrations in a residual brine. Both could be traced in the materials studied, and were found to be far more indicative than the ubiquitously studied concentrations of Cl and Na
Nonadjacent dependency processing in monkeys, apes and humans
The ability to track syntactic relationships between words, particularly over distances (“nonadjacent dependencies”), is a critical faculty underpinning human language, although its evolutionary origins remain poorly understood. While some monkey species are reported to process auditory nonadjacent dependencies, comparative data from apes are missing, complicating inferences regarding shared ancestry. Here, we examined nonadjacent dependency processing in common marmosets, chimpanzees, and humans using “artificial grammars”: strings of arbitrary acoustic stimuli composed of adjacent (nonhumans) or nonadjacent (all species) dependencies. Individuals from each species (i) generalized the grammars to novel stimuli and (ii) detected grammatical violations, indicating that they processed the dependencies between constituent elements. Furthermore, there was no difference between marmosets and chimpanzees in their sensitivity to nonadjacent dependencies. These notable similarities between monkeys, apes, and humans indicate that nonadjacent dependency processing, a crucial cognitive facilitator of language, is an ancestral trait that evolved at least ~40 million years before language itself
The Wnt pathway controls cell death engulfment, spindle orientation, and migration through CED-10/Rac
Wnt signalling pathways have extremely diverse functions in animals, including induction of cell fates or tumours, guidance of cell movements during gastrulation, and the induction of cell polarity. Wnt can induce polar changes in cellular morphology by a remodelling of the cytoskeleton. However, how activation of the Frizzled receptor induces cytoskeleton rearrangement is not well understood. We show, by an in depth 4-D microscopy analysis, that the Caenorhabditis elegans Wnt pathway signals to CED-10/Rac via two separate branches to regulate modulation of the cytoskeleton in different cellular situations. Apoptotic cell clearance and migration of the distal tip cell require the MOM-5/Fz receptor, GSK-3 kinase, and APC/APR-1, which activate the CED-2/5/12 branch of the engulfment machinery. MOM-5 (Frizzled) thus can function as an engulfment receptor in C. elegans. Our epistatic analyses also suggest that the two partially redundant signalling pathways defined earlier for engulfment may act in a single pathway in early embryos. By contrast, rearrangement of mitotic spindles requires the MOM-5/Fz receptor, GSK-3 kinase, and beta-catenins, but not the downstream factors LIT-1/NLK or POP-1/Tcf. Taken together, our results indicate that in multiple developmental processes, CED-10/Rac can link polar signals mediated by the Wnt pathway to rearrangements of the cytoskeleton
Effectiveness, safety and tolerability of a complex homeopathic medicinal product in the prevention of recurrent acute upper respiratory tract infections in children: a multicenter, open, comparative, randomized, controlled clinical trial
Background: The present study was initiated to investigate the effectiveness, safety and tolerability of complex homeopathic CalSuli-4-02 tablets on prevention of recurrent acute upper respiratory tract infections (URTIs) in children, in comparison to another complex homeopathic product. Methods: The study was designed as a prospective, multicenter, randomized, open, clinical trial with two parallel treatment groups at four outpatient pediatric clinics in Russia. Children aged <= 6 years with susceptibility to acute URTIs (>= three occasions during the last 6 months) were randomized to receive either CalSuli-4-02 or a comparator homeopathic product (control group) for 3 weeks. Primary outcome was the frequency of acute URTIs after 3 and 6 months post-treatment follow-up. Secondary endpoints were changes in complaints and symptoms (total and individual scores), treatment satisfaction, antibiotic use, safety and tolerability. Results: The intention-to-treat analysis involved 200 children (CalSuli-4-02: N = 99, Control: N = 101). In both treatment groups, the median number of acute URTIs was one for 3 months and two, respectively, for the full 6 months post-treatment (Relative Risk: 0.86 (95 %-CI: 0.72-1.03), p = 0.1099). Seasons had no influence on the outcome. At the end of study, CalSuli-4-02 had overall higher odds of getting lower complaints severity total score (Odds ratio: 1.99 (95 %-CI: 1.31-3.02), p = 0.0012) and showing symptom improvement (Odds ratio: 1.93 (95 %-CI: 1.25-3.00), p = 0.0033). Specifically, the complaint "appetite disorder" and the symptom "child's activities" significantly improved more in the CalSuli-4-02 group (p = 0.0135 and p = 0.0063, respectively). Antibiotic use was decreased in both treatment groups at the study end. Overall assessment for satisfaction with and tolerability of treatment was higher with CalSuli-4-02. A low number of non-serious adverse drug reactions was reported (CalSuli-4-02: N = 4, Control: N = 1). Conclusions: Both complex homeopathic products led to a comparable reduction of URTIs. In the CalSuli-4-02 group, significantly less URTI-related complaints and symptoms and higher treatment satisfaction and tolerability were detected. The observation that the use of antibiotics was reduced upon treatment with the complex homeopathic medications, without the occurrence of complications, is interesting and warrants further investigations on the potential of CalSuli-4-02 as an antibiotic sparing option
A model checking-based approach for security policy verification of mobile systems
International audienceThis article describes an approach for the automated verification of mobile systems. Mobile systems are characterized by the explicit notion of (e.g., sites where they run) and the ability to execute at different locations, yielding a number of security issues. To this aim, we formalize mobile systems as Labeled Kripke Structures, encapsulating the notion of that describes the hierarchical nesting of the threads constituting the system. Then, we formalize a generic that includes rules for expressing and manipulating the code location. In contrast to many other approaches, our technique supports both access control and information flow specification. We developed a prototype framework for model checking of mobile systems. It works directly on the program code (in contrast to most traditional process-algebraic approaches that can model only limited details of mobile systems) and uses abstraction-refinement techniques, based also on location abstractions, to manage the program state space. We experimented with a number of mobile code benchmarks by verifying various security policies. The experimental results demonstrate the validity of the proposed mobile system modeling and policy specification formalisms and highlight the advantages of the model checking-based approach, which combines the validation of security properties with other checks, such as the validation of buffer overflows
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