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The computational complexity of the MaxCut problem restricted to interval graphs has been open since the 80's, being one of the problems proposed by Johnson in his Ongoing Guide to NP-completeness, and has been settled as NP-complete only recently by Adhikary, Bose, Mukherjee, and Roy. On the other hand, many flawed proofs of polynomiality for MaxCut on the more restrictive class of unit/proper interval graphs (or graphs with interval count 1) have been presented along the years, and the classification of the problem is still unknown. In this paper, we present the first NP-completeness proof for MaxCut when restricted to interval graphs with bounded interval count, namely graphs with interval count 4. [ABSTRACT FROM AUTHOR]

The occurrence of plasma irregularities and ionospheric scintillation over the Caribbean region have been reported in previous studies, but a better understanding of the source and conditions leading to these events is still needed. In December 2021, three ground-based ionospheric scintillation and Total Electron Content monitors were installed at different locations over Puerto Rico to better understand the occurrence of ionospheric irregularities in the region and to quantify their impact on transionospheric signals. Here, the findings for an event that occurred on March 13–14, 2022 are reported. The measurements made by the ground-based instrumentation indicated that ionospheric irregularities and scintillation originated at low latitudes and propagated, subsequently, to mid-latitudes. Imaging of the ionospheric F-region over a wide range of latitudes provided by the GOLD mission confirmed, unequivocally, that the observed irregularities and the scintillation were indeed caused by extreme equatorial plasma bubbles, that is, bubbles that reach abnormally high apex heights. The joint ground- and space-based observations show that plasma bubbles reached apex heights exceeding 2600 km and magnetic dip latitudes beyond 28°. In addition to the identification of extreme plasma bubbles as the source of the ionospheric perturbations over low-to-mid latitudes, GOLD observations also provided experimental evidence of the background ionospheric conditions leading to the abnormally high rise of the plasma bubbles and to severe L-band scintillation. These conditions are in good agreement with the theoretical hypothesis previously proposed. [ABSTRACT FROM AUTHOR]

We have devoted efforts to the development and performance evaluation of new low-cost ionospheric instruments for studies that require distributed observations and for educational and citizen science initiatives. Here, we report results of some of these efforts. More specifically, we describe the design of new ionospheric sensors based on Global Navigation Satellite System (GNSS) receivers and single-board computers. The first sensor (ScintPi 2.0) is a multi-constellation, single-frequency ionospheric scintillation monitor. The second sensor (ScintPi 3.0) is a multi-constellation, dual-frequency ionospheric scintillation and total electron content (TEC) monitor. Both sensors were created using Raspberry Pi computers and off-the-shelf GNSS receivers. While they are not intended to fully replace commercial ionospheric monitors, they cost a fraction of their price and can be used in various scientific applications. In addition to describing these new sensors, we present examples of observations made by ScintPi 3.0 deployed in Presidente Prudente, Brazil (22.12 S, 51.41 W, − 17.67° dip latitude). These examples show the ability of our system to detect scintillation events and TEC depletions such as those associated with equatorial plasma bubbles. Additionally, our observations were made in parallel with a commercial receiver (Septentrio PolaRx5S), which allowed an evaluation of the scintillation and TEC measurements provided by our system. The comparison shows that ScintPi 3.0 can provide estimates of the amplitude scintillation index (S4) and TEC that are in excellent agreement with those provided by PolaRx5S. We also show an example of the application of ScintPi 3.0 in distributed observations of ionospheric irregularities and scintillation over South America. [ABSTRACT FROM AUTHOR]

We introduce a new numerical model developed to assist with Data Interpretation and Numerical Analysis of ionospheric Missions and Observations (DINAMO). DINAMO derives the ionospheric electrostatic potential at low- and mid-latitudes from a two-dimensional dynamo equation and user-specified inputs for the state of the ionosphere and thermosphere (I–T) system. The potential is used to specify the electric fields and associated F-region E × B plasma drifts. Most of the model was written in Python to facilitate the setup of numerical experiments and to engage students in numerical modeling applied to space sciences. Here, we illustrate applications and results of DINAMO in two different analyses. First, DINAMO is used to assess the ability of widely used I–T climatological models (IRI-2016, NRLMSISE-00, and HWM14), when used as drivers, to produce a realistic representation of the low-latitude electrodynamics. In order to evaluate the results, model E × B drifts are compared with observed climatology of the drifts derived from long-term observations made by the Jicamarca incoherent scatter radar. We found that the climatological I–T models are able to drive many of the features of the plasma drifts including the diurnal, seasonal, altitudinal and solar cycle variability. We also identified discrepancies between modeled and observed drifts under certain conditions. This is, in particular, the case of vertical equatorial plasma drifts during low solar flux conditions, which were attributed to a poor specification of the E-region neutral wind dynamo. DINAMO is then used to quantify the impact of meridional currents on the morphology of F-region zonal plasma drifts. Analytic representations of the equatorial drifts are commonly used to interpret observations. These representations, however, commonly ignore contributions from meridional currents. Using DINAMO we show that that these currents can modify zonal plasma drifts by up to ~ 16 m/s in the bottom-side post-sunset F-region, and up to ~ 10 m/s between 0700 and 1000 LT for altitudes above 500 km. Finally, DINAMO results show the relationship between the pre-reversal enhancement (PRE) of the vertical drifts and the vertical shear in the zonal plasma drifts with implications for equatorial spread F. [ABSTRACT FROM AUTHOR]

In this article, new fluorescent lipophilic based benzazoles were synthesized from the reaction between photoactive formyl derivatives and aliphatic amines followed by NaBH4 reduction with good yields. The photophysics of the benzazoles was investigated experimentally and theoretically. These compounds present absorption maxima in the UV region (∼339 nm) and fluorescence emission maxima in the cyan to green region with a large Stokes shift (∼175 nm) due to a proton transfer process in the excited state. Two fluorophores were successfully used as a proof of concept to produce stable photoactive liposomes prepared from phosphatidylcholine (PC) and were characterized by zeta potential, small angle X-ray scattering (SAXS), FTIR and UV-Vis experiments (turbidity). The scattering data indicate that the presence of compounds 20 and 23 reduces the overall surface charge of the PC vesicles, possibly due to the partial neutralization of phosphatidic acid and/or phosphatidylinositol phosphate by the amine groups, and they also modify the structural features of the assemblies, leading, in particular, to a reduction in the thickness of the hydrophobic inner segment (tt) of the liposomes. DFT and TD-DFT calculations were performed with the ̉B97XD functional. Geometric analyses show that the 2-(2′-hydroxyphenyl)benzazolic planar portion allows an effective ππ* electronic transition. Additionally, the calculations indicate a small energy barrier to proton transfer. The results of the absorption and emission maxima show a slight solvent influence on the wavelengths. [ABSTRACT FROM AUTHOR]

We present results of an effort to evaluate the ability of an analytic model to describe the behavior of the equatorial zonal plasma drifts given inputs provided by readily available climatological models of thermospheric and ionospheric parameters. In a data-model fusion approach, we used vertical drift measurements to drive the model and zonal drift measurements to evaluate its output. Drift measurements were made by the Jicamarca incoherent scatter radar, and model results were evaluated for different seasons and two distinct solar flux conditions. We focused, in particular, on model results for different versions of the Horizontal Wind Model (HWM 97, 07, and 14). We found that, despite its simplicity, the analytic model can reproduce fairly well most of the features in the observed zonal plasma drifts, including the vertical shear associated with the evening plasma vortex. During daytime hours the model predicts similar results for the zonal drifts independently of the HWM used to drive the model. More importantly, the modeled daytime drifts match exceptionally well the behavior and magnitude of the observed drifts for all seasons and solar flux conditions considered. The nighttime results drive the overall performance of the analytic model, and we found that a single HWM cannot provide the best results for all seasons and solar flux conditions. We also examined the main sources of zonal drift variability. Most of the morphology is controlled by the zonal wind dynamo term of the analytic model, but with non-negligible contribution from the vertical drift term. Finally, we examined the contribution from the E- and F-region to the zonal wind dynamo. The morphology of the zonal drifts in the region of observation (240–560 km altitude) is controlled mostly by the F-region winds, but with significant contributions from the daytime E-region particularly during December solstice and low solar flux conditions. [ABSTRACT FROM AUTHOR]

Efficient photoinduced electron transfer from proton transfer dyes encapsulated within water soluble supramolecular host octa acid to electron acceptors present outside the capsule was observed in aqueous solution. N-Methylpyridinium iodide was found to be the best acceptor compared to 4,4′-dimethylviologen dichloride, most likely due to its better binding with the exterior of the host octa acid walls. [ABSTRACT FROM AUTHOR]

The introduction of a high number of small cells in cellular networks and the complementary adoption of WLAN technologies in unlicensed spectrum are interesting options to attend the increasing demand for Internet traffic in wireless broadband access networks. One alternative for integrating both solutions is the aggregation of ISM unlicensed spectrum to licensed bands, using wireless networks defined by IEEE and 3GPP. While Wi-Fi networks are aggregated to LTE small cells via LTE/WLAN Aggregation (LWA), in proposals like LTE-U and LAA-LTE, the LTE air interface itself is used for transmission on the unlicensed band. Wi-Fi technology is widespread and also operates in the 5 GHz ISM spectrum bands, which may bring performance issues due to the coexistence of both technologies in the same spectrum band. This work is dedicated to the study of coexistence between LTE and Wi-Fi access systems operating in 5 GHz ISM Spectrum. A distributed coordination mechanism is proposed and evaluated via system-level simulations, and results indicate that the proposed solutions provide significant gains when compare to the situation without distributed coordination. [ABSTRACT FROM AUTHOR]

Typical equatorial spread-F events are often said to occur during post-sunset, equinox conditions in most longitude sectors. Recent studies, however, have found an unexpected high occurrence of ionospheric F-region irregularities during June solstice, when conditions are believed to be unfavorable for the development of plasma instabilities responsible for equatorial spread-F (ESF). This study reports new results of a multi-instrumented investigation with the objective to better specify the occurrence of these atypical June solstice ESF in the American sector and better understand the conditions prior to their development. We present the first observations of June solstice ESF events over the Jicamarca Radio Observatory (11.95° S, 76.87° W, ~ 1° dip latitude) made by a 14-panel version of the Advanced Modular Incoherent Scatter Radar system (AMISR-14). The observations were made between July 11 and August 4, 2016, under low solar flux conditions and in conjunction with dual-frequency GPS, airglow, and digisonde measurements. We found echoes occurring in the pre-, post-, and both pre- and post-midnight sectors. While at least some of these June solstice ESF events could have been attributed to disturbed electric fields, a few events also occurred during geomagnetically quiet conditions. The late appearance (22:00 LT or later) of three of the observed events, during clear-sky nights, provided a unique opportunity to investigate the equatorial bottomside F-region conditions, prior to ESF, using nighttime airglow measurements. We found that the airglow measurements (630 nm) made by a collocated all-sky camera show the occurrence of ionospheric bottomside F-region perturbations prior to the detection of ESF echoes in all three nights. The airglow fluctuations appear as early as 1 hour prior to radar echoes, grow in amplitude, and then coincide with ESF structures observed by AMISR-14 and GPS TEC measurements. They also show some of the features of the so-called large-scale wave structures (LSWS) that have been detected, previously, using other types of observations and have been suggested to be precursors of ESF. The bottomside fluctuations have zonal spacings between 300 and 500 km, are aligned with the magnetic meridian, and extend at least a few degrees in magnetic latitude. [ABSTRACT FROM AUTHOR]

The excited state behavior of two flavone derivatives 3-hydroxyflavone and 4′-N,N-diethylaminoflavonol in a confined medium indicates that supramolecular effects could alter the nature of the fluorescence emission. Within the octa acid host the neutral unionized species of these two dyes are present showing large Stokes shifted emission due to intramolecular proton transfer, a pattern different from that in aqueous medium. [ABSTRACT FROM AUTHOR]

Copyright of La Radiologia Medica is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carotid artery stenting (CAS) may be an alternative to surgical endoarterectomy not only in high-risk patients. We report results in the endovascular treatment of carotid artery disease with up to 8 years' follow-up. In this retrospective study, we analysed data from 853 consecutive patients (946 arteries) treated for carotid artery stenosis between April 1999 and March 2007; 491 (52%) arteries were symptomatic and 455(48%) were asymptomatic. Preprocedural evaluation of the patients was performed with echo Doppler, magnetic resonance angiography (MRA) or computed tomographic angiography (CTA) and a neurological examination. A cerebral protection device was used in 879 (92.9%) procedures. Anti-platelet therapy was administered before and after the procedure. All patients were included in a follow-up of up to 8 years. Technical success was achieved in 943 (99.6%) lesions. At 30 days, there was a 0.21% (n = 2) death rate, a 0.42% major stroke rate, a 1.69% minor stroke/transient ischaemic attack (TIA) rate and a combined 2.32% TIA/stroke and death rate. During follow-up, echo Doppler evidenced restenosis in 39 (4.85%) cases; of these, only five, presenting restenosis >80%, were treated with an endovascular reintervention. At the long-term follow-up, two strokes (0.23%) were reported, which both occurred within the first 2 years. In our experience, carotid artery stenting seems to be a safe and effective treatment, providing satisfactory long-term clinical results. [ABSTRACT FROM AUTHOR]

Copyright of La Radiologia Medica is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The American Heart Association modified classification for atherosclerotic plaque lesions has defined vulnerable plaques as those prone to rupture. The aim of our study was to assess the sensitivity and specificity of 1.5-T magnetic resonance imaging (MRI) in the evaluation of the characteristics of plaque components. Twelve carotid endarterectomy specimens were imaged by ex-vivo high-resolution 1.5-T MRI. Thirty-four cross-section axial images were selected for pixel-by-pixel basis analysis to demonstrate the most significant tissue features. Data were then submitted for histopathological examination and each specimen analysed in the light of the histological components (lipid core, fibrous tissue, fibrous/loose connective tissue, calcifications). The overall sensitivity and specificity rates for each tissue type were, respectively, 92% and 74% for the lipid core, 82% and 94% for the fibrous tissue, 72% and 87% for the fibrous/loose connective tissue, and 98% and 99% for calcification. The use of 1.5-T MRI appears to be a reliable tool to characterise plaque components and could help in the screening of patients with high risk of plaque rupture. The possibility of applying MRI in clinical daily practice may change the non-invasive approach to carotid artery diagnostic imaging, thus allowing an early identification of patients with vulnerable plaques. [ABSTRACT FROM AUTHOR]

We evaluated the long-term results of recanalization with primary stenting for patients with long and complex iliac artery occlusions. This was a retrospective nonrandomised study. Between 1995 and 1999, 138 patients underwent recanalization of an occluded iliac artery with subsequent stenting. Patency results were calculated using Kaplan-Meier analysis. The mean length of follow-up was 108 months. Variables affecting primary stent patency such as patient age; stent type and diameter; lesion site, shape, and length; Society of Cardiovascular and Interventional Radiology classification; total runoff score; Fontaine classification; and cardiovascular risk factors were analysed using Breslow test. These variables were then evaluated for their relation to stent patency using Cox proportional hazards test. Technical success was 99%. Primary patency rates were 90% (SE .024), 85% (SE .029), 80% (SE .034), and 68% (SE .052) at 3, 5, 7, and 10 years, respectively. Lesion site (p = 0.022) and stent diameter (p = 0.028) were shown to have a statistically significant influence on primary stent patency. Long-term results of iliac recanalization and stent placement were excellent, without major complications, even in highly complex vascular obstructions. A primary endovascular approach appears to be justified in the majority of patients as a less invasive alternative treatment to surgery. In any case, a first-line interventional approach should be considered in elderly patients or in patients with severe comorbidities. [ABSTRACT FROM AUTHOR]

In this paper, we present a fuzzy approach to the Reed-Frost model for epidemic spreading taking into account uncertainties in the diagnostic of the infection. The heterogeneities in the infected group is based on the clinical signals of the individuals (symptoms, laboratorial exams, medical findings, etc.), which are incorporated into the dynamic of the epidemic. The infectivity level is time-varying and the classification of the individuals is performed through fuzzy relations. Simulations considering a real problem with data of the viral epidemic in a children daycare are performed and the results are compared with a stochastic Reed-Frost generalization. [ABSTRACT FROM AUTHOR]

A 51-year-old man with an 8-year history of hypertension (170/115 mmHg with two drugs) and altered renal function (5.6 mg/dl serum creatinine, 101 mg/dl BUN) was referred to our Department to evaluate the renal arteries and rule out renovascular hypertension. Doppler ultrasound and magnetic resonance angiography revealed significant bilateral renal artery stenosis and the presence of bilateral renal artery aneurysms. A self-expandable polytetrafluoroethylene (PTFE)-covered nitinol stent-graft was deployed in each renal artery to treat the stenoses and to exclude the aneurysm. Postprocedural digital subtraction angiography confirmed the resolution of the renal artery stenoses and the complete exclusion of the aneurysms. At the 6 month follow-up, color Doppler confirmed normal patency of the renal arteries with complete exclusion of the aneurysms and significant reduction of the blood pressure (130/85 mmHg with one drug) and serum creatinine levels (2.1 mg/dl). [ABSTRACT FROM AUTHOR]

The efficacy of the “one-step” technique using two different metallic stents (Wallstent and Ultraflex) and associated rate of complications was studied in 87 patients with jaundice secondary to malignant biliary obstruction, with bilirubin level less than 15 mg/dl and Bismuth type 1 or 2 strictures. The study group, composed of 40 men and 47 women with a mean age of 59.4 years (range 37-81 years), was treated with a “one-step” percutaneous transhepatic implantation of self-expanding stents. The cause of the obstruction was pancreatic carcinoma in 38 patients (44%), lymph node metastasis in 20 patients (23%), gallbladder carcinoma in 13 patients (15%), cholangiocarcinoma in 12 patients (14%) and ampullary carcinoma in four patients (5%). A significant reduction in jaundice was obtained in all but one patient, with a drop of total serum bilirubin level from a mean of 13.7 mg/dl to 4.3 mg/dl within the first 4 days. The mean postprocedural hospitalization period was 5.4 days in the Wallstent group and 6.4 days in the Ultraflex group. Mean survival rate was 7.8 months (Wallstent group) and 7.1 months (Ultraflex group). The use of both stents did not reveal any significant difference in parameters tested. The implantation of these self-expandable stents in one session, in selected patients, is clinically effective, devoid of important complications and cost-effective due to the reduction in hospitalization. [ABSTRACT FROM AUTHOR]

Magnetic resonance Cholangiopancreatography (MRCP) is a non-invasive imaging technique able to provide projectional images of the bile ducts. Different sequences, using both breath-hold and non-breath-hold acquisition techniques, have been employed in order to obtain MRCP images. The authors discuss technical aspects, considering both three-dimensional non-breath-hold techniques and two-dimensional breath-hold, multi-slice and thick slab sequences. Clinical applications of MRCP are evaluated, presenting data from both the literature and personal experience. The main indication for MRCP study is represented by the evaluation of common bile duct obstruction, with the aim of assessing the presence of the obstruction (accuracy 85-100%) and, subsequently, its level (accuracy 91-100%) and its cause. The utility of associating conventional MR images to MRCP in malignant strictures, in order to characterize and stage the malignant lesion, is also discussed. Finally, data are presented regarding the indications and the utility of MR-pancreatography in the evaluation of patients with pancreatic duct anomalies and chronic pancreatitis. [ABSTRACT FROM AUTHOR]

Correction for ‘Photoinduced electron transfer across an organic molecular wall: octa acid encapsulated ESIPT dyes as electron donors’ by Fabiano S. Santos et al., Photochem. Photobiol. Sci., 2017, 16, 840–844. [ABSTRACT FROM AUTHOR]

Summary: A highly sensitive assay for rapidly screening-out Mycobacterium bovis in contaminated samples was developed based on electrochemical genosensing. The assay consists of specific amplification and double-tagging of the IS6110 fragment, highly related to M. bovis, followed by electrochemical detection of the amplified product. PCR amplification was carried out using a labeled set of primers and resulted in a amplicon tagged at each terminus with both biotin and digoxigenin. Two different electrochemical platforms for the detection of the double-tagged amplicon were evaluated: (i) an avidin biocomposite (Av-GEB) and (ii) a magneto sensor (m-GEC) combined with streptavidin magnetic beads. In both cases, the double- tagged amplicon was immobilized through its biotinylated end and electrochemically detected, using an antiDig-HRP conjugate, through its digoxigenin end. The assay was determined to be highly sensitive, based on the detection of 620 and 10 fmol of PCR amplicon using the Av-GEB and m-GEC strategies, respectively. Moreover, the m-GEC assay showed promising features for the detection of M. bovis on dairy farms by screening for the presence of the bacterium's DNA in milk samples. The obtained results are discussed and compared with respect to those of inter-laboratory PCR assays and tuberculin skin testing.