bluuebunny/crossref_metadata_2025_split huggingface dataset:
Operadores uniformes estables y subespacios invariantes
Authors: Rosales Edixo 
Published: April 2019

Este trabajo estudia operadores uniformemente estables sobre espacios de Banach en general, con el propósito de caracterizar algunos que tengan subespacios invariantes no triviales.

Palabras clave: Operadores Uniformemente estables, subespacios invariantes.

Abstract:

This paper studies uniformly stable operators on Banach spaces in general, with the purpose of characterizing some that have non-trivial invariant subspaces.

Key words: Uniformly stable operators, sub invariant spaces
Surgical management of middle cerebral artery aneurysms
Authors: Radoi Mugurel , Stefanescu Florin , Vakilnejad Ram 
Published: April 2019

Background. The middle cerebral artery (MCA) harbors approximately 14% to 30% of all ruptured cerebral aneurysms. They can occur at multiple sites throughout the course of the middle cerebral artery, but most often are found at the bifurcation of the first segment (M1).
Methods. A retrospective review of 116 consecutive patients with an MCA aneurysm treated by surgical clipping, by two senior neurosurgeons, was performed. The data of all our consecutive patients were searched to obtain patient characteristics, details of the aneurysm size and orientation, treatment details, complications and follow up. At admission, the clinical condition of all patients was classified according to the Hunt and Hess scale. Clinical outcome was graded according to the modified Rankin scale. The follow-up period varied widely from 2 to 72 months (mean 30 months).
Results. Surgical clipping was performed for 113 ruptured MCA aneurysms; only in 3 cases the aneurysm was unruptured. Fourteen patients presented with significant hematoma which required the evacuation of the clot. Post-operative control angiography was performed in 32 patients (27.5%), from which we reported a full occlusion of the aneurysm in 32 patients (93.75%). Perioperative mortality was 5.2% (6 patients), due to neurological (4 patients) or systemic causes (2 patients). The outcome was graded mRankin 0–2 in 72.5% of the cases (84 patients) at the end of the first postoperative months, and 78.5% (91 patients) at six months follow-up. The most important improvement was recorded for patients graded mRankin 1-2 at the first month follow-up. All 3 patients with a surgically treated asymptomatic MCA aneurysm had an excellent outcome (mRS 0) at both follow-up, 1 months and respectively 6 months.
Conclusions. For the experienced neurovascular team, MCA aneurysms currently make microsurgical treatment the preferred treatment modality for most MCA aneurysms.
Neuromodulation devices nowadays
Authors: Rizea R. E. , Gheorghita Karina Lidia , David Gh. , Ciurea A. V. 
Published: April 2019

Introduction. Neuromodulation devices have known a great progress in the past years being used in treatment of drug resistant neurological diseases such as epilepsies and migraines. A neuromodulation device can stimulate profound or superficial neural pathways in order to balance chronic drug-resistant disorders that involve disturbances of cellular electrical potentials.
Material. Cranial neuromodulation devices implants used until now usually determined skull irregularities, implant site infection, resorption of the bone flap or osteomyelitis. In order to solve these problems, it was needed a customized cranial implant that integrates the neuromodulation device. We report the first description of a fully integrated neuromodulation device within a customized cranial implant, publicised in 2018 by Gordon et al., that demonstrates the utility of a computerized neurostimulation device combined with clear custom-designed cranial implant.
Conclusion. The new approach of neurotechnology confines a better solution for neuroimplants devices with less follow-up complications and great patient’s satisfaction.
New technics for removal of intradural spinal tumours
Authors: Rizea R. E. , Gheorghita Karina Lidia , Salaceanu M. V. , Ciurea A. V. 
Published: April 2019

Introduction. Neuronavigation is a computer-assisted technology based on pre- and intraoperative images that permit neurosurgeons to have a better approach of the brain and intradural spinal tumors. The neuronavigation systems have been a significant progress in neurosurgery. These systems allow neurosurgeons to evaluate surgical risks, select the best interventional method, localize better the tumors in order to improve the accuracy of the resection and decide on the optimal trajectory for the surgical procedure, resulting in decreased patient morbidity and mortality.
Material: Spinal cord tumors are rare and uncommon lesions. Their growth result in compression of the spinal cord, which can cause severe neurologic deficits such as limb dysfunction, motor and sensation loss with the possibility of leading to death. We present o short report of a study publicated by Stefini et al. in 2018 regarding the use of neuronavigation for removal of intradural spinal tumors.
Conclusion: The benefits of using neuronavigation in resection of the intradural spinal tumors include decreased risk of bad localization of the tumor, minimal invasive surgery technique and reduction of bone removal.
Comparison of the predictive strength of total white blood cell count within 24 hours on the outcome of traumatic brain injury with cranial computed tomography scan in a resource-limited tertiary health centre in sub-Saharan Africa
Authors: Morgan Eghosa , Bankole Olufemi , Kanu Okezie , Ojo Omotayo , Poluyi Edward 
Published: April 2019

Background: The enormous disease burden of patients with traumatic brain injury (TBI) remains a huge source of concern to the patient and caregivers. Computed tomography (CCT) scan is a valuable investigative tool in patients with traumatic brain injury which can be used to predict the outcome of TBI. The use of total white blood cell as a predictive parameter in patients with TBI is still at a primordial stage. This study aimed to compare the predictive strength of total WBC count within 24 hours of TBI with cranial computed tomography scan.
Methods: This research was done over one-year period at the Lagos University Teaching Hospital, Lagos. One hundred and fifty-eight patient who met the inclusion criteria were studied and the male to female ratio of 3.6:1.
Results: The mean total WBC count was 14,279.94 and the area under the curve of total WBC count and CCT scan was 0.633 and 0.855 respectively.
Conclusion: Our conclusion was that despite both parameters been a predictor of the outcome of TBI, the total white blood cell is a weaker predictor of outcome compared to cranial computerize tomography scan.
Silent Pauses in the Speech of Yemeni EFL Learners
Authors: Al-Ghazali Abeer Mohammed , Alrefaee Yasser 
Published: April 2019

Speaking fluently is characterized not only by the speed of oral delivery but also by the absence of non-fluent pauses. This paper aims at investigating the pausing phenomena in the speech of the Yemeni learners of English. It investigated three aspects of silent pauses, the frequency, the placement and the length. The data were collected from 20 level four students enrolled in the Department English Language, Faculty of Education, Taiz University. The participants were recorded narrating the events of a short silent video immediately after watching it. Data were analyzed quantitatively utilizing the waveform spectrogram software called PRAAT. The findings showed that the Yemeni EFL learners overused non-fluent silent pauses. Additionally, they paused in the middle of the clauses rather than at the clause boundaries. With respect to the mean length of silent pauses, the speech of the EFL learners at Taiz University was full of long silent pauses which took one-third of the total speaking time. Therefore, it is highly suggested that the teachers of English should draw the learners’ attention to the notion of pausing and its effect on speaking fluency in order to lessen or avoid it. Teachers should also vary their activities to help the learners speak fluently without much pausing.
Localized Microwave and EUV Bright Structures in an Eruptive Prominence
Authors: Huang Jing , Tan Baolin , Masuda Satoshi , Cheng Xin , Kumar Bisoi Susanta , Melnikov Victor 
Published: April 2019

Abstract
We study a solar eruptive prominence with flare/coronal mass ejection (CME) event by microwave and extreme ultraviolet (EUV) observations. Its evolution can be divided into three phases: slow rise, fast expansion, and ejection. In the slow-rise phase, the prominence continuously twists for more than one hour with a patch of bright emission appearing around the top. When the north leg interacts with the local small-size loops, the fast expansion is initiated and the flare takes place there. The prominence grows rapidly, and a series of localized brightenings appear in the whole prominence structure. Then the ejection occurs, followed by a CME. In microwave images, the brightness temperature (T

b
) at 17 and 34 GHz can be divided into three components. The strongest emission with T

b
at 25,000–300,000 K is related to the bright flare region near the north foot. The medium T

b
(10,000–20,000 K) outlines a series of small-scale bright enhancements scattering in the prominence, which are superposed on a weak background with T

b
at 5000–10,000 K. These localized bright structures, first appearing at the top and then scattering in the entire prominence structure, are cospatial with EUV bright threads, fibers, or spots in both high- and low-temperature passbands. They display significant temporal variations on the scale of 3–5 s in the microwave observations. Thus, the plasma inside the prominence is spatially structured and changes with time in both density and temperature. This behavior could be interpreted in the frame of the small-scale and short-term process of energy releases in the twisted magnetic structure.
Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star∗
Authors: Guillot Sebastien , Pavlov George G. , Reyes Cristobal , Reisenegger Andreas , Rodriguez Luis E. , Rangelov Blagoy , Kargaltsev Oleg 
Published: April 2019

Abstract
We report nondetections of the ∼3 × 108 yr old, slow, isolated, rotation-powered pulsar PSR J2144–3933 in observations with the Hubble Space Telescope in one optical band (F475X) and two far-ultraviolet bands (F125LP and F140LP), yielding upper bounds

,

, and

, at the pivot wavelengths 4940 Å, 1438 Å and 1528 Å, respectively. Assuming a blackbody spectrum, we deduce a conservative upper bound on the surface (unredshifted) temperature of the pulsar of

42,000 K. This makes PSR J2144–3933 the coldest known neutron star, allowing us to study thermal evolution models of old neutron stars. This temperature is consistent with models with either direct or modified Urca reactions including rotochemical heating, and, considering frictional heating from the motion of neutron vortex lines, it puts an upper bound on the excess angular momentum in the neutron superfluid, J < 1044 erg s.
Behavior of trap-and-transported Atlantic salmon spawners of hatchery origin in the Daugava River system (Latvia)
Authors: Nyqvist Daniel , Zagars Matiss , Calles Olle , Comoglio Claudio 
Published: April 2019

Where migrating fish have to pass multiple dams, very high passage performance is required at the series of obstacles to avoid accumulated negative effects of multiple dam passage. In some rivers, migrating fish are trapped, transported past several obstacles, and released to continue their migration. Such trap-and-transport solutions, however, have seldom been evaluated. In the Daugava River, Latvia, several dams with no functional fishways block the river for migrating fish. A remnant Atlantic salmon population is being sustained by a sea ranching regime, where returning spawners are caught and artificially spawned, the juveniles raised in hatcheries, and smolts released in to the river in time for their seaward migration. Hatchery released fish, however, differ substantially from wild conspecifics, and in Latvia, as elsewhere throughout the range of salmon, reduced dependency on hatchery production and the re-establishment of wild salmon populations are being discussed. In the Daugava River system, suitable spawning and rearing habitat remains upstream two dams and an associated large reservoir in a mainstem tributary, the Ogre River, offering the potential to restore a wild salmon population. To explore the potential of a trap-and-transport solution to bring Atlantic salmon spawners in contact with remaining spawning grounds in the Daugava River system, spawners were caught, radio tagged, transported upstream of the two dams and the reservoir, and released to pursue their spawning migration in the tributary. Despite being unfamiliar with the river, some of the tagged spawners moved upstream, reaching areas up to 12 km from the release sites. Males were observed higher upstream in the river compared to females, and some males were tracked relatively close to potential salmon spawning habitat. Females, although displaying some movements in the lower parts of the river, were not observed close to any suitable spawning areas, highlighting potentially important sex differences in post trap-and-transport behaviour. Perhaps due to different responses to handling stress, such low post-transportation spawning success among females has the potential to negatively impact restoration efforts in the Daugava River system and elsewhere. The present study represents a first step towards the restoration of wild Daugava salmon, one of several unique Baltic Atlantic salmon populations, and a potential model for future restoration efforts.
Congenital biotinidase deficiency – MRI findings in two cases
Authors: Ranjan Rahul S , Taneja Sunil , Singh Anil , Gupta Vikas 
Published: April 2019

AbstractCongenital biotinidase deficiency is a rare inborn error of metabolism that most commonly presents in infantile age group. Diffusion changes on magnetic resonance imaging (MRI) are sparsely described in the literature. We are presenting diffusion-weighted MRI findings in two confirmed cases of congenital biotinidase deficiency in infantile age group with review of literature.
Cardiac T2* magnetic resonance analysis of membranous interventricular septum in assessment of cardiac iron overload in pediatric thalassemia patients: A pilot study
Authors: Kumar Ishan , Aggarwal Priyanka , Gupta Vineeta , Verma Ashish , Kumar Suwen , Shukla Ram C 
Published: April 2019

Abstract
Background: Cardiac iron deposition in transfusion-dependent thalassemia patients is patchy in distribution. Purpose: The purpose of this study is to assess the correlation between T2* matrices of membranous interventricular septum (MIVS) and T2* values of muscular interventricular septum (IVS) on magnetic resonance imaging (MRI) and to evaluate the relationship of myocardial T2* at these two locations with MRI-estimated liver iron concentrations (LIC) and electrocardiographic (ECG) parameters. Material and Methods: MRI of heart and liver was performed in 16 consecutive pediatric patients of transfusion-dependent thalassemia major to calculate liver iron concentration and T2* time of membranous and muscular IVS. ECG parameters of these patients were charted and correlated with MRI parameters. Results: No significant correlation between T2* values of muscular IVS and MIVS was observed. Mean T2* of MIVS (9.8 ms) was significantly lower than that of muscular IVS (26.9 ms). T2* of MIVS correlated strongly with LIC where as a weak correlation was observed between T2* of IVS and LIC. Significantly higher mean QTc (corrected QT interval) value (439.86 ms) was seen in patients with T2* IVS <20 ms. Conclusion: Addition of T2* analysis of MIVS to the existing MRI protocol, consisting of muscular IVS analysis, may offer a more sensitive estimation of cardiac iron overload.
Non-radiation occupational hazards and health issues faced by radiologists – A cross-sectional study of Indian radiologists
Authors: Kawthalkar Ameya S , Sequeira Rachel A , Arya Supreeta , Baheti Akshay D 
Published: April 2019

Abstract
Context: Radiologists as a group face unique occupational health hazards among which musculoskeletal injuries, chronic eye strain, and others are yet to receive adequate attention. Constant mental strain due to demanding turnaround times and work pressures may lead to burnout and depression. These combine to decrease overall work satisfaction and productivity. Aims: To study the prevalence of various health issues faced by radiologists in India and to assess whether specific demographic and occupational factors are associated with an increased risk. Settings and Design: Cross-sectional observational study conducted as a voluntary anonymous electronic survey. Methods and Materials: A 36-item survey was sent to radiologists through email and social media. All respondents who completed survey were included in the study. Questions regarding workload, repetitive stress injuries, eye strain, burnout, and so on were asked. Statistical Analysis Used: Chi-square test was used to test significance of correlation (P < 0.05). Results: In all, 383 radiologists completed the survey. A high prevalence of repetitive stress injuries, chronic eye strain, depression, and burnout was found. Significant correlation was found between repetitive stress injuries and burnout. Pre-Conception and Pre-Natal Diagnostic Techniques Act (PCPNDT) related issues and work overload were the most common causes of high stress levels. Radiologists whose practices followed ergonomic design showed significantly less prevalence of neck pain. Conclusion: Radiologists in India have a high prevalence of repetitive stress injuries, chronic eye strain, and burnout, along with unique mental stressors such as PCPNDT-related issues.
Predictors of metabolic response in propensity-matched lymphoma patients on interim 18F-fluorodeoxyglucose positron-emission tomography/computed tomography using standardized imaging and reporting protocol: Do we really have one?
Authors: Fatima Nosheen , Zaman Maseeh Uz , Zaman Areeba , Zaman Unaiza , Tahseen Rabia , Zaman Sidra 
Published: April 2019

AbstractThe purpose of this prospective study was to determine metabolic response predictor(s) in propensity-matched patients having lymphomas who had baseline and interim 18fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) using strict standardized imaging and reporting protocols. This prospective study was conducted at PET/CT section of a JCI-accredited healthcare facility from April 2017 to February 2018. Patients with baseline and interim 18FDG PET/CT scans using standardized protocol were selected. Interim scans were performed not earlier than 2nd or later than 4th chemotherapy. During the study period, 97 of 112 consecutive patients with lymphomas (Hodgkin-HL: 32/97 and Non-Hodgkin-NHL: 65/97) were included in the study. Mean age of cohort was 45 ± 19 years (71% male and 29% female) having a mean body mass index (BMI) of 25.57 ± 5.54 Kg/m2 having Stage I (21%), Stage II (18%), Stage III (16%), and Stage IV (45%) disease. Bulky disease was found in 14% and 18FDG-avid marrow deposits in 33%. Standardized PET/CT imaging protocol as per EANM guidelines was strictly adopted for baseline and interim studies. %Δ changes in fasting blood sugar,18FDG dose, uptake time, and liver SUV mean were 3.96%, 2.83%, 2.49%, and 12.15%, respectively. Based on Deauville's scoring, cohort was divided into responders having Score 1–3 (49/97) and nonresponders having Score 4–5 (48/97). The demographic analysis found no significant difference between responders and nonresponders for age, gender, BMI, staging, bulky disease or marrow involvement, and study protocol. No significant coefficient or odd ratios were found on multivariate analysis for age, gender, maximum standardized uptake value (SUVmax), size, BMI, NHL, and advance disease (Stage III and IV) in both groups (χ2: 5.12; receiver operating characteristic [95% confidence interval]: 0.616 [0.51–0.713]; P=0.528). Among responders, baseline SUVmaxand tumor size had a direct correlation with a metabolic response on iPET, more pronounced in NHL than HL groups (SUVmax: 13.4 vs. 19.5 and size: 52 vs. 87 mm; P < 0.0001). We conclude that no significant predictor was found for response in propensity-matched patients with lymphomas (both HL and NHL) who had baseline and interim PET/CTs acquired with a standardized protocol. However, NHL responders were found to have higher baseline median SUVmaxand larger lesion size as compared to HL responders. Although, these data are not in concordance with published findings but need to be validated with larger studies using standardized imaging and reporting protocols in propensity-matched patients with lymphomas.
Novel specular meteor radar systems using coherent MIMO techniques to study the mesosphere and lower thermosphere
Authors: Chau Jorge Luis , Urco Juan Miguel , Vierinen Juha Pekka , Volz Ryan Andrew , Clahsen Matthias , Pfeffer Nico , Trautner Jörg 
Published: April 2019

Abstract. Typical specular meteor radars (SMRs) use one transmitting antenna and at
least a five-antenna interferometric configuration on reception to study the
mesosphere and lower thermosphere (MLT) region. The interferometric
configuration allows the measurement of the angle-of-arrival (AOA) of the
detected meteor echoes, which in turn is needed to derive atmospheric
parameters (e.g., mean winds, momentum fluxes, temperatures, and neutral
densities). Recently, we have shown that coherent MIMO configurations in
atmospheric radars, i.e., multiple input (transmitters) and multiple output
(receivers), with proper diversity in transmission can be used to enhance
interferometric atmospheric and ionospheric observations. In this study we
present novel SMR systems using multiple transmitters in interferometric
configuration, each of them employing orthogonal pseudorandom coded
transmitted sequences. After proper decoding, the angle of departure (AOD) of
the detected meteor echoes with respect to the transmitter site are obtained
at each receiving antenna. We present successful bistatic implementations of
(1) five transmitters and one receiver using coded continuous wave (CW)
(MISO-CW), and (2) five transmitters and five receivers using coded CW
(MIMO-CW). The latter system allows simultaneous independent observations of
the specular meteor trails with respect to the transmitter (AOD) and with
respect to the receiver (AOA). The quality of the obtained results is
evaluated in terms of the resulting mean winds, the number of detections and
the daily diffusion trail vs. altitude behavior. We show that the proposed
configurations are good alternatives to explore the MLT region. When combined
with multi-static approaches, they can increase the number of meteor
detections, thereby improving the quality of atmospheric estimates and
allowing the measurement of new atmospheric parameters (e.g., horizontal
divergence, vorticity), The use of multiple collocated transmitters for
interferometric AOD determination makes building a multi-static radar network
easier logistically, as only one receiver per receiving site antenna is
sufficient.