Understanding how fast short-range interactions build up long-range order is one of the most intriguing topics in condensed matter physics. FeRh is a test specimen for studying this problem in ...magnetism, where the microscopic spin-spin exchange interaction is ultimately responsible for either ferro- or antiferromagnetic macroscopic order. Femtosecond laser excitation can induce ferromagnetism in antiferromagnetic FeRh, but the mechanism and dynamics of this transition are topics of intense debates. Employing double-pump THz emission spectroscopy has enabled us to dramatically increase the temporal detection window of THz emission probes of transient states without sacrificing any loss of resolution or sensitivity. It allows us to study the kinetics of emergent ferromagnetism from the femtosecond up to the nanosecond timescales in FeRh/Pt bilayers. Our results strongly suggest a latency period between the initial pump-excitation and the emission of THz radiation by ferromagnetic nuclei.
Childhood arteriopathies are rare but heterogenous, and difficult to diagnose and classify, especially by nonexperts. We quantified clinical and imaging characteristics associated with childhood ...arteriopathy subtypes to facilitate their diagnosis and classification in research and clinical settings.
The Vascular Effects of Infection in Pediatric Stroke (VIPS) study prospectively enrolled 355 children with arterial ischemic stroke (2010-2014). A central team of experts reviewed all data to diagnose childhood arteriopathy and classify subtypes, including arterial dissection and focal cerebral arteriopathy-inflammatory type, which includes transient cerebral arteriopathy, Moyamoya disease, and diffuse/multifocal vasculitis. Only children whose stroke etiology could be conclusively diagnosed were included in these analyses. We constructed logistic regression models to identify characteristics associated with each arteriopathy subtype.
Among 127 children with definite arteriopathy, the arteriopathy subtype could not be classified in 18 (14%). Moyamoya disease (
= 34) occurred mostly in children younger than 8 years of age; focal cerebral arteriopathy-inflammatory type (
= 25), in children 8-15 years of age; and dissection (
= 26), at all ages. Vertigo at stroke presentation was common in dissection. Dissection affected the cervical arteries, while Moyamoya disease involved the supraclinoid internal carotid arteries. A banded appearance of the M1 segment of the middle cerebral artery was pathognomonic of focal cerebral arteriopathy-inflammatory type but was present in <25% of patients with focal cerebral arteriopathy-inflammatory type; a small lenticulostriate distribution infarct was a more common predictor of focal cerebral arteriopathy-inflammatory type, present in 76%. It remained difficult to distinguish focal cerebral arteriopathy-inflammatory type from intracranial dissection of the anterior circulation. We observed only secondary forms of diffuse/multifocal vasculitis, mostly due to meningitis.
Childhood arteriopathy subtypes have some typical features that aid diagnosis. Better imaging methods, including vessel wall imaging, are needed for improved classification of focal cerebral arteriopathy of childhood.
Cerebral and cervical arterial abnormalities are the most common non-cutaneous anomaly in PHACE syndrome, but the location and type of arterial lesions that occur have not been systematically ...assessed in a large cohort. Our aim was to characterize the phenotypic spectrum of arteriopathy, assess the frequency with which different arteries are involved, and evaluate spatial relationships between arteriopathy, brain structural lesions, and hemangiomas in PHACE syndrome.
Intracranial MRA and/or CTA images from 70 children and accompanying brain MR images in 59 patients with arteriopathy and PHACE syndrome were reviewed to identify the type and location of arterial lesions and brain abnormalities. Five categories of arteriopathy were identified and used for classification: dysgenesis, narrowing, nonvisualization, primitive embryonic carotid-vertebrobasilar connections, and anomalous arterial course or origin. Univariate logistic regression analyses were performed to test for associations between arteriopathy location, hemangiomas, and brain abnormalities.
By study design, all patients had arterial abnormalities, and 57% had >1 form of arteriopathy. Dysgenesis was the most common abnormality (56%), followed by anomalous course and/or origin (47%), narrowing (39%), and nonvisualization (20%). Primitive embryonic carotid-vertebrobasilar connections were present in 20% of children. Hemangiomas were ipsilateral to arteriopathy in all but 1 case. The frontotemporal and/or mandibular facial segments were involved in 97% of cases, but no other specific associations between arteriopathy location and hemangioma sites were detected. All cases with posterior fossa anomalies had either ICA anomalies or persistent embryonic carotid-basilar connections.
The arteriopathy of PHACE syndrome commonly involves the ICA and its embryonic branches, ipsilateral to the cutaneous hemangioma, with dysgenesis and abnormal arterial course the most commonly noted abnormalities. Brain abnormalities are also typically ipsilateral.
The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in ...2008 and completed in 2013, the project was supported by three Large Program allocations, as well as various programmes initiated by independent principal investigators, and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada–France–Hawaii Telescope, Narval at the Télescope Bernard Lyot and HARPSpol at the European Southern Observatory La Silla 3.6 m telescope, making MiMeS by far the largest systematic investigation of massive star magnetism ever undertaken. In this paper, the first in a series reporting the general results of the survey, we introduce the scientific motivation and goals, describe the sample of targets, review the instrumentation and observational techniques used, explain the exposure time calculation designed to provide sensitivity to surface dipole fields above approximately 100 G, discuss the polarimetric performance, stability and uncertainty of the instrumentation, and summarize the previous and forthcoming publications.
Despite increasing awareness of the long-term impact of pediatric stroke, there are few estimates of the costs of care. We examined acute and 5-year direct costs of neonatal and childhood stroke in a ...population-based cohort in Northern California.
We obtained electronic cost data for 266 children with neurologist-confirmed strokes, and 786 age-matched stroke-free controls, within the population of all children (<20 years) enrolled in a large managed care plan from 1996 through 2003. Cost data included all inpatient and outpatient health service costs including care at out-of-plan facilities. Costs were assessed for 5 years after stroke, expressed in 2003 US dollars, and stratified by age at stroke onset (neonatal, defined as <29 days of life, vs childhood). Stroke costs were adjusted for costs in stroke-free age-matched controls.
Average adjusted 5-year costs for pediatric stroke are substantial: $51,719 for neonatal stroke and $135,161 for childhood stroke. The average cost of a childhood stroke admission was $81,869. The average birth admission cost for a neonatal stroke was $39,613; adjustment for control birth admission costs reduced this by only $4,792, suggesting the stroke accounted for 88% of costs. Even among neonates whose strokes were not recognized until later in childhood ("presumed perinatal strokes"), admission costs exceeded those of controls. Chronic costs were highest in the first year poststroke, but continued to exceed control costs even in the fifth year by an average of $2,016.
The economic burden of neonatal and childhood stroke is both large and sustained.
Pediatric aneurysms are rare and, thus, relatively poorly understood as compared to those in adults. Our aim was to characterize the clinical, imaging, treatment, and outcome data of patients younger ...than 19 years diagnosed with intracranial aneurysms at a tertiary care institution.
We performed a retrospective medical record review of pediatric patients examined at our university hospital between 1981 and 2008.
We evaluated 77 patients (mean age, 12 years; 40 female, 37 male) with 103 intracranial aneurysms. Patients presented with headache (45%), cranial neuropathies (16%), nausea/vomiting (15%), vision changes (13%), trauma (13%), seizure (4%), or sensory changes (3%). Subarachnoid hemorrhage occurred in 25 patients. Thirty-one fusiform aneurysms occurred in 25 patients. Forty-seven saccular aneurysms occurred in 35 patients. Twelve infectious aneurysms occurred in 6 patients. Fifteen traumatic aneurysms occurred in 12 patients. Fifty-nine patients underwent treatment of their aneurysms; 18 patients' conditions were managed conservatively. Nineteen patients underwent primary endovascular coiling, 1 patient had endovascular stent-assisted coiling, 11 patients underwent endovascular parent artery occlusion, 19 patients underwent surgical clipping, and 10 patients had aneurysms trapped and bypassed. Mortality was 1.3%. Morbidity included 8% infarction and 4% new-onset seizures. Six patients developed new aneurysms or had enlargement of untreated aneurysms.
In our experience, intracranial aneurysms of childhood show a female predilection and predominantly saccular morphology. In neurovascular centers where microneurosurgical and endovascular options are available, most children with intracranial aneurysms can be successfully treated with low morbidity and mortality. Fusiform aneurysms require a combined microneurosurgical and endovascular approach more often than saccular aneurysms. The development of new aneurysms in pediatric patients during limited follow-up warrants further investigation.
Objective:Family history is an established risk factor for mental illness. The authors sought to investigate whether polygenic scores (PGSs) can complement family history to improve identification of ...risk for major mood and psychotic disorders.Methods:Eight cohorts were combined to create a sample of 1,884 participants ages 2–36 years, including 1,339 offspring of parents with mood or psychotic disorders, who were prospectively assessed with diagnostic interviews over an average of 5.1 years. PGSs were constructed for depression, bipolar disorder, anxiety, attention deficit hyperactivity disorder (ADHD), schizophrenia, neuroticism, subjective well-being, p factor, and height (as a negative control). Cox regression was used to test associations between PGSs, family history of major mental illness, and onsets of major mood and psychotic disorders.Results:There were 435 onsets of major mood and psychotic disorders across follow-up. PGSs for neuroticism (hazard ratio=1.23, 95% CI=1.12–1.36), schizophrenia (hazard ratio=1.15, 95% CI=1.04–1.26), depression (hazard ratio=1.11, 95% CI=1.01–1.22), ADHD (hazard ratio=1.10, 95% CI=1.00–1.21), subjective well-being (hazard ratio=0.90, 95% CI=0.82–0.99), and p factor (hazard ratio=1.14, 95% CI=1.04–1.26) were associated with onsets. After controlling for family history, neuroticism PGS remained significantly positively associated (hazard ratio=1.19, 95% CI=1.08–1.31) and subjective well-being PGS remained significantly negatively associated (hazard ratio=0.89, 95% CI=0.81–0.98) with onsets.Conclusions:Neuroticism and subjective well-being PGSs capture risk of major mood and psychotic disorders that is independent of family history, whereas PGSs for psychiatric illness provide limited predictive power when family history is known. Neuroticism and subjective well-being PGSs may complement family history in the early identification of persons at elevated risk.
NGAVFs are rare vascular malformations usually presenting in infancy or childhood. We sought to identify clinical and angiographic predictors of clinical outcome for these lesions.
Retrospective ...review of a neurointerventional data base identified 386 pediatric patients with intracranial AVFs and AVMs, from which a cohort of 25 patients with NGAVF were selected for medical record and imaging analysis.
NGAVFs constituted 7.3% of pediatric intracranial vascular lesions with a nondural arteriovenous shunt. Seven of 8 patients who presented in the first month of life had CHF and harbored large, complex fistulas with multiple sites of arteriovenous shunting. Single-hole fistulas predominated later in childhood and more frequently presented with seizures, hemorrhage, or focal neurologic deficits. More treatment procedures were performed in subjects presenting at ≤ 2 years of age compared with older children (median = 3 versus 2, P = .041), and in those harboring a multi-hole fistula versus those with a single-hole fistula (median = 3 versus 2, P = .003). Eighteen patients (72%) had complete posttreatment elimination of NGAVF shunting. Compared with patients presenting at >2 years of age, patients presenting in the first 2 years of life were more likely to have a multi-hole fistula (100% versus 25%, P = .0001) and to have a poor clinical outcome (54% versus 0%, P = .0052), defined as a pediatric mRS of ≥ 3.
The morbidity of NGAVF appears higher than previously reported despite a somewhat higher rate of angiographic cure. Poor clinical outcome occurred primarily in patients with multi-hole NGAVFs presenting at ≤ 2 years of age.
In 1998, the Stroke Prevention Trial in Sickle Cell Anemia showed a >90% reduction in stroke rates after blood transfusion therapy in children with sickle cell disease (SCD) identified as high risk ...with transcranial Doppler ultrasonography (TCD) screening.
We studied the utilization of TCD screening in a retrospective cohort of all children with SCD within a large managed care plan from January 1993 to December 2005. Rates of first TCD screening were estimated using life table methods; predictors of TCD were evaluated using Cox proportional hazards regression. Stroke incidence rates were estimated in person-time before (pre-TCD) and after (post-TCD) first TCD.
The average annual rate of TCD screening in 157 children with SCD was 1.8 per 100 person-years pre-1998, 5.0 from January 1, 1998, to December 31, 1999, and 11.4 after 1999. The only independent predictor of TCD screening was proximity to the vascular laboratory. The annualized stroke rate pre-TCD was 0.44 per 100 person-years, compared to 0.19 post-TCD.
Since the Stroke Prevention Trial in Sickle Cell Anemia, the rate of transcranial Doppler ultrasonography (TCD) screening in sickle cell disease (SCD) has increased sixfold within a large health care plan. Children living farther from a vascular laboratory are less likely to be screened. Increased availability of TCD screening could improve the utilization of this effective primary stroke prevention strategy.
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