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Miguel Berdugo, Sonia Kéfi, Santiago Soliveres, Fernando T Maestre
The response of drylands to environmental gradients can be abrupt rather than gradual. These shifts largely occur unannounced and are difficult to reverse once they happen; their prompt detection is of crucial importance. The distribution of vegetation patch sizes may indicate the proximity to these shifts, but the use of this metric is hampered by a lack of large-scale studies relating these distributions to the provision of multiple ecosystem functions (multifunctionality) and comparing them to other ecosystem attributes, such as total plant cover...
January 9, 2017: Nature ecology & evolution
Anna Ochab-Marcinek, Jakub Jędrak, Marcin Tabaka
An intuition based on deterministic models of chemical kinetics is that population heterogeneity of transcription factor levels in cells is transmitted unchanged downstream to the target genes. We use a stochastic model of a two-gene cascade with a self-regulating upstream gene to show that, counter to the intuition, there is no simple mapping (bimodal to bimodal, unimodal to unimodal) between the shapes of the distributions of transcription factor numbers and target protein numbers in cells. Due to the presence of the two regulations, the system contains two nonlinear transfer functions, defined by the Hill kinetics of transcription factor binding...
August 15, 2017: Physical Chemistry Chemical Physics: PCCP
Nicholas J York, Christopher Tinley
BACKGROUND: Corneal pathology is one of the leading causes of preventable blindness in South Africa (SA). A corneal transplant can restore or significantly improve vision in most cases. However, in SA there is a gross shortage of corneal tissue available to ophthalmologists. Little has been published describing the magnitude of the problem. OBJECTIVES: To describe trends in the number of corneal donors per year in SA, the number of corneal transplants performed each year, the origin of donors, the allocation of corneas to the public or private sector, and the demographics of donors...
July 28, 2017: South African Medical Journal, Suid-Afrikaanse Tydskrif Vir Geneeskunde
Kei K Suzuki, Motokazu Ando
Seasonal changes of activity patterns are an important survival strategy for several species. Seasonal changes in the activity patterns of Japanese flying squirrels (Pteromys momonga) were studied at Daibosatsu Mountain on Honshu Island, Japan from 2 June to 20 November 2007 and 11 April to 14 November 2008, to discuss their survival strategy based on the change. Activity patterns were assessed using long-term sensor camera traps at 214 sites for 14 months of a 2-year period. The cameras were placed for a total of 7,317 camera trap nights over which total of 90 photographs of this species were collected from 22 of the 214 sites...
August 11, 2017: Behavioural Processes
Mattia Pegoraro, Slavica Matić, Barbara Pergolizzi, Luca Iannarelli, Andrea M Rossi, Marco Morra, Emanuela Noris
Enamel is the covering tissue of teeth, made of regularly arranged hydroxyapatite crystals deposited on an organic matrix composed of 90% amelogenin that is completely degraded at the end of the enamel formation process. Amelogenin has a biomineralizing activity, forming nanoparticles or nanoribbons that guide hydroxyapatite deposit, and regenerative functions in bone and vascular tissue and in wound healing. Biotechnological products containing amelogenin seem to facilitate these processes. Here, we describe the production of human amelogenin in plants by transient transformation of Nicotiana benthamiana with constructs carrying synthetic genes with optimized human or plant codons...
August 11, 2017: Molecular Biotechnology
Cheng-Yu Shih, Maxim V Shugaev, Chengping Wu, Leonid V Zhigilei
The ability of short pulse laser ablation in liquids to produce clean colloidal nanoparticles and unusual surface morphology has been employed in a broad range of practical applications. In this paper, we report the results of large-scale molecular dynamics simulations aimed at revealing the key processes that control the surface morphology and nanoparticle size distributions by pulsed laser ablation in liquids. The simulations of bulk Ag targets irradiated in water are performed with an advanced computational model combining a coarse-grained representation of liquid environment and an atomistic description of laser interaction with metal targets...
August 3, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Zoltan Nagy, Peter Mukli, Peter Herman, Andras Eke
Physiological processes-such as, the brain's resting-state electrical activity or hemodynamic fluctuations-exhibit scale-free temporal structuring. However, impacts common in biological systems such as, noise, multiple signal generators, or filtering by transport function, result in multimodal scaling that cannot be reliably assessed by standard analytical tools that assume unimodal scaling. Here, we present two methods to identify breakpoints or crossovers in multimodal multifractal scaling functions. These methods incorporate the robust iterative fitting approach of the focus-based multifractal formalism (FMF)...
2017: Frontiers in Physiology
Ruili Wang, Eric Habib, X X Zhu
OBJECTIVE: The aim of this work is to explore the reinforcing effect of wrinkled mesoporous silica (WMS), which should allow micromechanical resin matrix/filler interlocking in dental resin composites, and to investigate the effect of silica morphology, loading, and compositions on their mechanical properties. METHODS: WMS (average diameter of 496nm) was prepared through the self-assembly method and characterized by the use of the electron microscopy, dynamic light scattering, and the N2 adsorption-desorption measurements...
August 7, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
Parvej Alam, Nelson Lik Ching Leung, Huifang Su, Zijie Qiu, Ryan T K Kwok, Jacky W Y Lam, Ben Zhong Tang
The detection of food spoilage is a major concern in food safety as large amounts of food are transported globally. Direct analysis of food samples is often time-consuming and requires expensive analytical instrumentation. A much simpler and more cost-effective method for monitoring food fermentation is to detect biogenic amines generated as a by-product during food decomposition. In this work, a series of 1,2-dihydroquinoxaline derivatives (DQs) with aggregation-induced emission (AIE) characteristics were synthesized and their protonated forms, i...
August 10, 2017: Chemistry: a European Journal
Mingquan Liu, Tri Minh Tran, Ahmed Awad Abbas Elhaj, Silje Bøen Torsetnes, Ole Nørregaard Jensen, Börje Sellergren, Knut Irgum
Thirty-five melamine-formaldehyde (MF) monolithic materials with bimodal pore distributions were synthesized in fused silica capillaries by catalyst-free polycondensation, starting with an aqueous MF precondensate, using acetonitrile as macroporogen and a variety of aliphatic polyethers and triblock copolymeric surfactants as porogens and mesoporogens, respectively. By varying the prepolymer composition and the type and molecular weights of the polymeric porogen components, a library of porous monolithic materials were produced, covering a range of meso- and macroporous properties...
August 10, 2017: Analytical Chemistry
Helge Abildhauge Thomsen, Jette Buch Østergaard
The examination and statistical analysis of loricate choanoflagellate material collected from Greenland waters during the period 1988-1998 represents a de facto baseline study of heterotrophic nanoflagellates from the Atlantic Arctic Region. The geographic sites sampled are Disko Bay (West Greenland) and the high-arctic North-East Water (NEW) and North Water (NOW) polynya. The analyses encompass close to 50 taxa. Some of these are described as new species, i.e. Acanthocorbis glacialis, A. reticulata and Diaphanoeca dilatanda...
July 2017: Heliyon
Gao Guo, Ke Gong, Amyn A Habib
Epidermal growth factor receptor (EGFR) plays an important role in various types of human cancers. Overexpression of EGFR leads to a constitutive tyrosine phosphorylation of multiple tyrosine residues in the EGFR. Recently, we have demonstrated that overexpressed EGFR oscillates between two distinct and mutually exclusive modes of signaling depending on the presence or absence of ligand. EGFR constitutively activates transcription factor IRF3, which results in transcription of its target genes. Addition of EGF causes a loss of IRF3 transcriptional activity and activation of canonical signaling pathways such as ERK...
2017: Methods in Molecular Biology
Lige Geng, Dewayne D Deng, Martin J Wubben, Johnie N Jenkins, Jack C McCarty, Ibrokhim Abdurakhmonov
In crop research programs that implement transgene-based strategies for trait improvement it is necessary to distinguish between transgene homozygous and hemizygous individuals in segregating populations. Direct methods for determining transgene zygosity are technically challenging, expensive, and require specialized equipment. In this report, we describe a standard PCR-based protocol coupled with capillary electrophoresis that can identify transgene homozygous and hemizygous individuals in a segregating population without knowledge of transgene insertion site...
2017: Frontiers in Plant Science
Hervé Leh, Ahmad Khodr, Marie-Christine Bouger, Bianca Sclavi, Sylvie Rimsky, Stéphanie Bury-Moné
In enteropathogenic Escherichia coli (EPEC), the locus of enterocyte effacement (LEE) encodes a type 3 secretion system (T3SS) essential for pathogenesis. This pathogenicity island comprises five major operons (LEE1 to LEE5), with the LEE5 operon encoding T3SS effectors involved in the intimate adherence of bacteria to enterocytes. The first operon, LEE1, encodes Ler (LEE-encoded regulator), an H-NS (nucleoid structuring protein) paralog that alleviates the LEE H-NS silencing. We observed that the LEE5 and LEE1 promoters present a bimodal expression pattern, depending on environmental stimuli...
August 8, 2017: MBio
Shilong Yang, Fan Yang, Bei Zhang, Bo Hyun Lee, Bowen Li, Lei Luo, Jie Zheng, Ren Lai
Venomous animals use peptide toxins for hunting and self-defense. To achieve these goals, toxins need to bind to their targets with high affinity due to the small amount that a single bite or sting can deliver. The scorpion toxin BmP01 is linked to sting-induced excruciating pain; however, the reported minimum concentrations for activating TRPV1 channel or inhibiting voltage-gated potassium (Kv) channels (both in the micromolar range) appear too high to be biologically relevant. We show that the effective concentration of BmP01 is highly pH-dependent-it increases by about 10-fold in inhibiting Kv channels upon a 1-U drop in pH but decreases more than 100-fold in activating TRPV1...
August 2017: Science Advances
Francois-Marie Allioux, Oana David, Miren Etxeberria Benavides, Lingxue Kong, David Alfredo Pacheco Tanaka, Ludovic F Dumée
The sintering of metal powders is an efficient and versatile technique to fabricate porous metal elements such as filters, diffusers, and membranes. Neck formation between particles is, however, critical to tune the porosity and optimize mass transfer in order to minimize the densification process. In this work, macro-porous stainless steel (SS) hollow-fibers (HFs) were fabricated by the extrusion and sintering of a dope comprised, for the first time, of a bimodal mixture of SS powders. The SS particles of different sizes and shapes were mixed to increase the neck formation between the particles and control the densification process of the structure during sintering...
August 4, 2017: Membranes
Banghua Chen, Ayako Sumi, Lei Wang, Wang Zhou, Nobumichi Kobayashi
BACKGROUND: Chickenpox is a common contagious disease that remains an important public health issue worldwide. Over 90% of unvaccinated individuals become infected, but infection occurs at different ages in different parts of the world. Many people have been infected by 20 to 30 years of age in China, and adults and pregnant women who become infected often develop severe infection. Furthermore, a mortality rate of 2-3 per 100,000 infected persons has been reported. In this study, we explore the temperature-dependent transition of patterns of reported chickenpox cases in two large subtropical climate cities, Wuhan and Hong Kong, China, to aid in the prediction of epidemics and preparation for the effects of climatic changes on epidemiology of chickenpox in China...
August 3, 2017: BMC Infectious Diseases
Weili Cheng, Liang Tian, Shichao Ma, Yang Bai, Hongxia Wang
An I-phase containing Mg-8Sn-6Zn-2Al (wt %; TZA862) alloy was fabricated and subjected to different number of passes of equal channel angular pressing (ECAP) processing at 300 °C. The results showed that the alloys exhibited a bimodal microstructure, which consisted of fine dynamically recrystallized (DRX) grains and coarse non-DRX grains. When increasing the number of ECAP passes from 2 to 6, the fraction of DRX grains and the dispersed second phase particles subsequently increase. However, the fraction and particles then decrease once the number of ECAP passes increases to 8...
June 27, 2017: Materials
Hernan Lara-Padilla, Christian Mendoza-Buenrostro, Diego Cardenas, Aida Rodriguez-Garcia, Ciro A Rodriguez
The combination of different materials and capabilities to manufacture at several scales open new possibilities in scaffold design for bone regeneration. This work is focused on bimodal scaffolds that combine polylactic acid (PLA) melt extruded strands with polycaprolactone (PCL) electrospun fibers. This type of bimodal scaffold offers better mechanical properties, compared to the use of PCL for the extruded strands, and provides potential a means for controlled drug and/or growth factor delivery through the electrospun fibers...
June 11, 2017: Materials
Isabel Montealegre-Meléndez, Cristina Arévalo, Eva M Perez-Soriano, Erich Neubauer, Cristina Rubio-Escudero, Michael Kitzmantel
In this work, a study of the influence of the starting materials and the processing time used to develop W/Cu alloys is carried out. Regarding powder metallurgy as a promising fabrication route, the difficulties in producing W/Cu alloys motivated us to investigate the influential factors on the final properties of the most industrially demanding alloys: 85-W/15-Cu, 80-W/20-Cu, and 75-W/25-Cu alloys. Two different tungsten powders with large variation among their particle size-fine (Wf) and coarse (Wc) powders-were used for the preparation of W/Cu alloys...
February 8, 2017: Materials
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