Transition in the Fractal Geometry of Arctic Melt Ponds

During the Arctic melt season, the sea ice surface undergoes a remarkable transformation from vast expanses of snow covered ice to complex mosaics of ice and melt ponds. Sea ice albedo, a key parameter in climate modeling, is determined by the complex evolution of melt pond configurations. In fact, ice–albedo feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding melt pond evolution remains a significant challenge to improving climate projections. By analyzing area–perimeter data from hundreds of thousands of melt ponds, we find here an unexpected separation of scales, where pond fractal dimension D transitions from 1 to 2 around a critical length scale of 100 m2 in area. Pond complexity increases rapidly through the transition as smaller ponds coalesce to form large connected regions, and reaches a maximum for ponds larger than 1000 m2, whose boundaries resemble space-filling curves, with D ≈ 2. These universal features of Arctic melt pond evolution are similar to phase transitions in statistical physics. The results impact sea ice albedo, the transmitted radiation fields under melting sea ice, the heat balance of sea ice and the upper ocean, and biological productivity such as under ice phytoplankton blooms

Conceptual Understanding for Systems of Linear Equations: Difficulties and Challenges

The conceptual understanding of algebraic concepts is challenging to students, adds to the challenge of teaching them. This study aimed to reveal the level of conceptual understanding about Systems of Linear Equations (SLEs) and its difficulties that faced students while they solving problems. The study sample consisted of (68) male and female students of linear algebra course. The conceptual understanding test was prepared with two qualitative and quantitative rubrics to classify students’ levels. The study results showed a decrease in the conceptual understanding of SLEs in general, and in the area of realizing the relationships between concepts related to SLEs in particular. In contrast, the level of conceptual understanding of students was medium in the context of multiple representations. The results also showed many difficulties that students face while solving SLEs. The study recommended the need to focus on the conceptual understanding of concepts related to SLEs and to use multiple representations and connect them together when teaching mathematical concepts

Synchronization of a renewable energy inverter with the grid

The design, mathematical analysis, and testing results of the architecture of a new all-digital phase-locked loop system for synchronizing a voltage source DC-AC single-phase inverter with the low voltage utility grid are presented. The system which is based on the time-delay digital tanlock loop was simulated using MATLAB/ SIMULINK and was tested by subjecting the grid voltage to various perturbations similar to those which can occur in a real power system, such as voltage sags and nonlinear distortion of the grid voltage waveform. Results indicate that even in the presence of such perturbations the system achieved and/or re-gained synchronization within 100 ms. The proposed system is all-digital and can be readily implemented using a field programmable gate array and easily embedded into a power inverter

7-O-methylpunctatin, a novel homoisoflavonoid, inhibits phenotypic switch of human arteriolar smooth muscle cells

Remodeling of arterioles is a pivotal event in the manifestation of many inflammation-based cardio-vasculopathologies, such as hypertension. During these remodeling events, vascular smooth muscle cells (VSMCs) switch from a contractile to a synthetic phenotype. The latter is characterized by increased proliferation, migration, and invasion. Compounds with anti-inflammatory actions have been successful in attenuating this phenotypic switch. While the vast majority of studies investigating phenotypic modulation were undertaken in VSMCs isolated from large vessels, little is known about the effect of such compounds on phenotypic switch in VSMCs of microvessels (microVSMCs). We have recently characterized a novel homoisoflavonoid that we called 7-O-methylpunctatin (MP). In this study, we show that MP decreased FBS-induced cell proliferation, migration, invasion, and adhesion. MP also attenuated adhesion of THP-1 monocytes to microVSMCs, abolished FBS-induced expression of MMP-2, MMP-9, and NF-?B, as well as reduced activation of ERK1/2 and FAK. Furthermore, MP-treated VSMCs showed an increase in early (myocardin, SM-22?, SM-?) and mid-term (calponin and caldesmon) differentiation markers and a decrease in osteopontin, a protein highly expressed in synthetic VSMCs. MP also reduced transcription of cyclin D1, CDK4 but increased protein levels of p21 and p27. Taken together, these results corroborate an anti-inflammatory action of MP on human microVSMCs. Therefore, by inhibiting the synthetic phenotype of microVSMCs, MP may be a promising modulator for inflammation-induced arteriolar pathophysiology. - 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported by the American University of Beirut (Grant # MPP 320133 to A.E.), University of Petra (Grant #: 5/4/2019) to A.B., E.B., and A.E., and the National Council for Scientific Research (CNRS) to M.F.Scopu

Genotypic and phenotypic characterization of enteric bacteria in an integrated population of swine and humans

In two longitudinal studies, we examined the transmission dynamics of antimicrobial resistance (AMR) in an integrated, semi-closed population of humans and swine

Longitudinal Study of Antimicrobial Resistance among Escherichia coli Isolates from Integrated Multisite Cohorts of Humans and Swine

In a 3-year longitudinal study, we examined the relationship between the seasonal prevalence of antimicrobial-resistant (AR) Escherichia coli isolates from human wastewater and swine fecal samples and the following risk factors: the host species, the production type (swine), the vocation (human swine workers, non-swine workers, and slaughter plant workers), and the season, in a multisite, vertically integrated swine and human population representative of a closed agri-food system. Human and swine E. coli (n = 4,048 and 3,429, respectively) isolates from wastewater and fecal samples were tested for antimicrobial susceptibility, using the Sensititre broth microdilution system. There were significant (P < 0.05) differences among AR E. coli prevalence levels of (i) the host species, in which swine isolates were at higher risk for resistance to tetracycline, kanamycin, ceftiofur, gentamicin, streptomycin, chloramphenicol, sulfisoxazole, and ampicillin; (ii) the swine production group, in which purchased boars, nursery piglets, and breeding boars isolates had a higher risk of resistance to streptomycin and tetracycline; and iii) the vocation cohorts, in which swine worker cohort isolates exhibited lower sulfisoxazole and cefoxitin prevalence than the non-swine worker cohorts, while the slaughter plant worker cohort isolates exhibited elevated cefoxitin prevalence compared to that of non-swine workers. While a high variability was observed among seasonal samples over the 3-year period, no significant temporal trends were apparent. There were significant differences in the prevalence levels of multidrug-resistant isolates between host species, with swine at a higher risk of carrying multidrug-resistant strains than humans. Considering vocation, slaughter plant workers were at higher risk of exhibiting multidrug-resistant E. coli than non-swine workers

Calculating coherent light-wave propagation in large heterogeneous media

Understanding the interaction of light with a highly scattering material is essential for optical microscopy of optically thick and heterogeneous biological tissues. Ensemble-averaged analytic solutions cannot provide more than general predictions for relatively simple cases. Yet, biological tissues contain chiral organic molecules and many of the cells' structures are birefringent, a property exploited by polarization microscopy for label-free imaging. Solving Maxwell's equations in such materials is a notoriously hard problem. Here we present an efficient method to determine the propagation of electro-magnetic waves in arbitrary anisotropic materials. We demonstrate how the algorithm enables large scale calculations of the scattered light field in complex birefringent materials, chiral media, and even materials with a negative refractive index

Applying Benford’s law to detect accounting data manipulation in the banking industry

We utilise Benford’s Law to test if balance sheet and income statement data broadly used to assess bank soundness were manipulated prior to and also during the global financial crisis. We find that all banks resort to loan loss provisions to manipulate earnings and income upwards. Distressed institutions that have stronger incentives to conceal their financial difficulties resort additionally to manipulating loan loss allowances and non-performing loans downwards. Moreover, manipulation is magnified during the crisis and expands to encompass regulatory capital

The Glasgow Outcome Scale -- 40 years of application and refinement

The Glasgow Outcome Scale (GOS) was first published in 1975 by Bryan Jennett and Michael Bond. With over 4,000 citations to the original paper, it is the most highly cited outcome measure in studies of brain injury and the second most-cited paper in clinical neurosurgery. The original GOS and the subsequently developed extended GOS (GOSE) are recommended by several national bodies as the outcome measure for major trauma and for head injury. The enduring appeal of the GOS is linked to its simplicity, short administration time, reliability and validity, stability, flexibility of administration (face-to-face, over the telephone and by post), cost-free availability and ease of access. These benefits apply to other derivatives of the scale, including the Glasgow Outcome at Discharge Scale (GODS) and the GOS paediatric revision. The GOS was devised to provide an overview of outcome and to focus on social recovery. Since the initial development of the GOS, there has been an increasing focus on the multidimensional nature of outcome after head injury. This Review charts the development of the GOS, its refinement and usage over the past 40 years, and considers its current and future roles in developing an understanding of brain injury