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We present a 24-year-old man with a 2-year history of progressive right-sided monocular vision loss with no other symptoms. An MRI showed a meningioma compressing the right optic nerve and the cavernous sinus. The tumour was partially resected. Eight days after discharge the patient was admitted with fever, a severe stabbing headache, insomnia, nausea and vomiting. A FilmArray panel and a cerebral biopsy were performed which were positive for herpes simplex virus 1 (HSV-1). An MRI of the brain showed asymmetric bilateral lesions in the frontobasal region with predominance of the right side. Acyclovir was started and continued until completing 21 days. A month after discharge, he started experiencing insomnia, trichotillomania, limb tremor, persistence of abulia, apathy and emotional lability. An HSV-1 encephalitis relapse was suspected, acyclovir and foscarnet were started. Due to the poor response to antiviral therapy CSF was tested, which was positive for anti-NMDA receptor encephalitis. A treatment course of intravenous immunoglobulin was started with a favourable outcome.

Objectives The COVID-19 pandemic has led to the disruption of all sectors of the economy including education. According to UNESCO over 1.37 million young people including medical students, were affected by the lockdowns in response to COVID-19 and the subsequent closure of the education system. The primary challenge for medical education was to provide clerkships in a biosafety environment. This study aimed to determine the impact of a simulated hospital in a neurology clerkship of 5-year medical students during the coronavirus pandemic and compare their results with a non-pandemic group in Bogotá, Colombia. Results The students in the pandemic group answered a Likert scale survey regarding their satisfaction with the simulated hospital. Both groups were required to perform an oral, mid-term and final examination. From the results, it is clear that students perceived that exposure to a simulated hospital facilitated their learning process (93.1%) and allowed greater interaction with the teacher compared to a face-to-face environment (77.3%). There were no clinically significant differences in test results. This experience indicates that a simulated hospital is a valuable method to acquire clinical skills in trainees, that could be integrated into the curricular milestones of medical education programs regardless of the pandemic.

Stroke is one of the manifestations of COVID-19-associated coagulopathy. Arterial infarcts are the most common presentation; however involvement of both arterial and venous irrigation is possible but rare. We report, what is, to our knowledge, the second case of concomitant arterial and venous brain thrombosis evidenced in magnetic resonance. A 62-year-old man presented with acute weakness of the left hand and lack of coordination in the left arm. Nine days earlier, he was positive for SARS-CoV-2 RT-PCR. The brain images revealed two subacute infarcts, one corresponding to the territory of the right middle cerebral artery, and the other in the right frontal cortical vein. The existence of both venous and arterial brain infarcts due to COVID-19 infection, has been previously reported once. Most of the cases of stroke are due to only arterial thrombosis; therefore, this could be the starting point to start collecting data about simultaneous compromise in order to assess and compare outcomes, severity of the disease, among other variables.

Neuroimmunology is a discipline that increasingly broadens its horizons in the understanding of neurological diseases. At the same time, and in front of the pathophysiological links of neurological diseases and immunology, specific diagnostic and therapeutic approaches have been proposed. Despite the important advances in this discipline, there are multiple dilemmas that concern and filter into clinical practice. This article presents 15 controversies and a discussion about them, which are built with the most up-to-date evidence available. The topics included in this review are: steroid decline in relapses of multiple sclerosis; therapeutic recommendations in MS in light of the SARS-CoV-2 pandemic; evidence of vaccination in multiple sclerosis and other demyelinating diseases; overview current situation of isolated clinical and radiological syndrome; therapeutic failure in multiple sclerosis, as well as criteria for suspension of disease-modifying therapies; evidence of the management of mild relapses in multiple sclerosis; recommendations for prophylaxis against Strongyloides stercolaris; usefulness of a second course of immunoglobulin in the Guillain-Barré syndrome; criteria to differentiate an acute-onset inflammatory demyelinating chronic polyneuropathy versus Guillain-Barré syndrome; and, the utility of angiotensin-converting enzyme in neurosarcoidosis. In each of the controversies, the general problem is presented, and specific recommendations are offered that can be adopted in daily clinical practice.La neuroinmunología es una disciplina que cada vez amplía más sus horizontes en la comprensión de las enfermedades neurológicas. Contemporáneamente, y a la luz de los nexos fisiopatológicos de las enfermedades neurológicas y la inmunología, se han planteado enfoques diagnósticos y terapéuticos específicos. A pesar de los importantes avances de esta disciplina, existen múltiples dilemas que le conciernen y se filtran en la práctica clínica. En esta revisión, se presentan y discuten 15 controversias, las cuales se construyen con la información clínica disponible más actualizada. Los temas incluidos son: disminución de esteroides en recaídas de esclerosis múltiple; recomendaciones terapéuticas en esclerosis múltiple a la luz de la pandemia por el SARS-CoV-2; evidencia de vacunación en esclerosis múltiple y en otras enfermedades desmielinizantes; panorama actual del síndrome clínico y radiológico aislado; y fallas terapéuticas en esclerosis múltiple; además, criterios para suspender las terapias modificadoras de la enfermedad; evidencia del manejo en recaídas leves; recomendaciones para la profilaxis contra Strongyloides stercolaris; utilidad de un segundo ciclo de inmunoglobulina en el síndrome de Guillain-Barré; criterios para diferenciar una polineuropatía crónica desmielinizante inflamatoria de inicio agudo de un síndrome de Guillain-Barré y, utilidad de la enzima convertidora de angiotensina en neurosarcoidosis. En cada una de las controversias, se presenta la problemática general y se ofrecen recomendaciones específicas que pueden adoptarse en la práctica clínica diaria.

ObjectiveTo characterize a case series of Colombian patients with autoimmune encephalitis (AE).BackgroundAE is often an under-recognized entity and antibody testing is not widely available in many developing countries. There is a lack of population-based data on AE in Colombia.Design/MethodsWe made a comprehensive review of the literature on AE in Colombia. Additionally, we contacted researchers in other tertiary care institutions in Bogotá, Colombia to obtain information on additional unpublished cases.Results45 individuals were included and antibodies were identified in 73.3% of them. The most prevalent antibody was NMDA followed by LGI-1. Clinical characteristics according to the specific antibody were similar to those reported in the literature. Interestingly 1 patient had Zika virus (ZIKV) encephalitis 4 months before developing LGI-1 AE, and another patient developed an immunodeficiency following a NMDA related AE. A total of 5 patients had a negative antibody screen. There was no data on antibodies in 7 patients.ConclusionsThe clinical phenotypes of patients with AE in our case series were similar to those previously published. It is important to highlight a novel infectious trigger (ZIKV) and a postencephalitic immune mediated complication that, to the best of our knowledge, have not been previously reported in the literature. The initial diagnostic approach of AE can be based on clinical findings and conventional tests, especially in countries with limited resources where antibody testing is not accessible to all clinicians.

RESUMEN La esclerosis múltiple (EM) es la más frecuente de las enfermedades desmielinizantes del sistema nervioso central. Se trata de una patología compleja, con mecanismos fisiopatológicos aún no elucidados completamente y una presentación clínica variada. Es una entidad crónica, de alto costo para el sistema de salud, y usualmente se asocia a una importante discapacidad en los pacientes afectados. No existe una cura para la EM, sin embargo, se cuenta con más de 13 terapias modificadoras de la enfermedad que actúan en distintas dianas terapéuticas, enlentecen la progresión y mejoran el pronóstico. El objetivo de este escrito es presentar una actualización de EM, a través de 16 preguntas y temas controversiales. Estos 16 puntos responden a dudas puntuales y actuales, son presentados, analizados y, en los casos en los que la evidencia lo permite, se plantean recomendaciones. Las preguntas abordadas incluyen temas como diagnóstico, tratamiento, uso de nuevas tecnologías y manejo de los efectos adversos. Este escrito está destinado a neurólogos, médicos generales, residentes de neurología y cualquier profesional interesado en las enfermedades desmielinizantes. SUMMARY Multiple sclerosis (MS) is the most common demyelinating disorder of the central nervous system. It is a complex disease, with a pathogenesis not fully understood and multiple clinical presentations. MS is a chronic disease, represents a great cost to healthcare systems and is often associated with a high burden of disability in patients. Despite the absence of a cure, there are at least13 disease-modifying therapies that act on different targets of the pathogenic process. The main purpose of this review is to solve 16 controversial and current topics in MS. These 16 topics are analysed, and when there is enough evidence, we issue recommendations. The topics include diagnosis, treatment, use of new technologies in MS, and medication side effects. This paper is meant for neurologists, neurology residents, general physicians and any other healthcare personnel interested in demyelinating diseases.

The Devonian connection between the Brooks Range of Alaska, USA, with the continental margin of Arctic Canada and its subsequent Jurassic–Cretaceous counterclockwise rotation to form the Amerasian Basin, is a highly debated topic in Arctic tectonics. This resource-rich region was assembled from terranes that formed part of Laurentia or Baltica, or were juvenile oceanic arcs in the early Paleozoic that were brought together during Caledonian Orogenesis and the subsequent collision that formed Pangea (Uralide Orogeny). Elements of these orogens, as well as older ones, are predicted to occur in the Brooks Range of Arctic Alaska. This study presents the first combined zircon U-Pb and oxygen data from six Brooks Range metasedimentary units with assumed Neoproterozoic to Devonian ages. Three distinct detrital zircon patterns are identified in these units: (1) those with Neoproterozoic maximum depositional ages characteristic of the Timanide Orogen of northern Baltica and adjacent parts of Siberia, (2) an almost unimodal Siluro–Ordovician (443.5 ± 2.3 Ma) detrital zircon population consistent with the oceanic Apoon arc believed to have existed off shore of northern Laurentia and to have accreted to the North Slope subterrane during the Caledonian event, and (3) those with Middle Devonian maximum depositional ages consistent with post-accretion extension during the final (Scandian) phase of Caledonian Orogenesis. Oxygen isotopes from the same zircons reveal minor to significant crustal contamination with approximately two thirds (n = 255/405) having δ18O values >5.9‰ (above the mantle field of 5.3 ± 0.6‰). Pattern 1 units exhibit a progressive increase in δ18O values throughout the Proterozoic (5.99 to 9.29‰) indicative of increasing crustal growth and Timanide age zircons yield average δ18O values of 7.18 ± 0.64‰ (n = 26) suggestive of more crustal influence than Caledonian age zircons, possibly reflecting northern Baltica signatures. The unimodal population in Pattern 2 yields average δ18O values of 5.49 ± 0.66‰ (n = 17) and 6.02 ± 0.27‰ (n = 23) prior to and during, respectively, the main Caledonian event and suggest derivation from Devonian juvenile arc sources possibly representing the initiation of the collision between Laurentia and Baltica. Similar to Pattern 1, the δ18O values associated with Pattern 3 show a progressive increase in δ18O values throughout the Proterozoic (5.00 to 9.39‰). However, Pattern 3 also exhibits a distinct juvenile fingerprint (6.13 ± 0.24‰, n = 51) during the main Caledonian event and a slight increase to 7.12 ± 1‰ (n = 7) in post-Caledonian zircons possibly suggest correlating with a post-accretion phase in which proximally sourced zircon-bearing detritus was deposited in extension-related basins marking the joining of Laurentia and Baltica.

Background Multiple sclerosis (MS) is a demyelinating disease with a lifetime prevalence of 4.41/100000 in Bogota, Colombia. It is known that it can be related with neuropsychiatric disorders, increasing by a factor of three the prevalence of depression in MS patients compared to general population. However, less attention has been given to the association between MS and impulsive behavior. Methods This cross-sectional study compared the levels of impulsivity controlling for the presence of MS. 60 patients with MS and 60 sex- and age-matched subjects without MS were included. In order to assess depression and impulsivity, participants completed the 13-item short form of the Beck Depression Inventory (BDI-SF), the self-report Barratt Impulsiveness Scale version 11 (BIS-11) and the Immediate and Delayed Memory Tasks (IMT-DMT) as an objective measure of impulsive behavior. Results Total scores, motor and cognitive subscales on the BIS-11 were significantly higher in the MS group. However, median BDI-SF score was also higher in MS patients than in subjects without MS (p

Objective The aim of this study was to explore the association between MS and vitamin D levels, as well as Epstein-Barr virus (EBV) seropositivity and smoking history in a Colombian population. Methods : We conducted a cross-sectional study between 2017 and 2018. We measured vitamin D levels and EBV antibody titers and administered a questionnaire to assess dietary habits, smoking, second-hand smoking and duration of smoking, sunlight exposure, physical activity, and personal and family history in individuals with and without multiple sclerosis during adolescence. A multivariable logistic regression model was then performed to explore the association between vitamin D status and MS. Results : A total of 87 individuals with MS (mean age 40.9 years; 65.52% females) and 87 without MS (mean age 55 years; 65.52% females) were included in the analysis. In the multivariable analysis, after controlling for supplementation vitamin D levels did not differ between both groups and no difference was found regarding tobacco smoke exposure. The proportion of individuals who tested positive for anti-EBV nuclear antigen was significantly higher in individuals with MS (95.4% vs 82.76%, p = 0.028) Conclusion : We did not find a statistically significant association between MS and vitamin D levels while anti-EBV nuclear antigen titers behaved as previously described in the literature. This study provides new evidence of the association between MS and different risk factors in our country, reinforcing the hypothesis that the pathogenesis of MS is multifactorial. Further studies are needed to better define the association between environmental factors and the development of MS in low prevalence areas.

We report the case of a 54-year-old immunocompetent woman who presented with a primary T-cell/histiocyte-rich large B-cell lymphoma (TCHRLBCL) of the central nervous system without systemic involvement, diagnosed by means of a brain biopsy. She was treated with corticosteroids and we subsequently started chemotherapy with rituximab, methotrexate, ifosfamide and intrathecal cytarabine. The patient’s symptoms gradually improved over the first weeks and we followed-up with autologous haematopoietic cell transplantation. The patient has been in complete remission for a year. Primary TCHRLBCL of the central nervous system in an immunocompetent patient is an extremely rare condition that requires a multidisciplinary approach. This case highlights the importance of undergoing a sequential work-up and establishing a treatment despite the absence of evidence-based guidelines.

AIM To determine the prevalence of drug and substance abuse among high school students in Jalisco and its association with the severity of health, behavior and psychosocial problems in order to provide evidence for possible prevention and treatment needs. METHODS A multi-stage random sample of Jalisco high school students was given a paper-and-pencil survey based upon an adapted version of the drug use screening inventory (DUSI) (n = 24699; n = 2832). The DUSI showed adequate psychometric characteristics in this population. The statistical analyses accommodated the complex survey design with attention to unequal probability of selection and clustering of participants within schools and regions. RESULTS An estimated 44% of the students had smoked tobacco, one in five students was a current smoker, and one in four students used to smoke but had not smoked for one year or more. By contrast, 6.8% of the students reported having used marijuana, cocaine, or both. Behavioral problems, deviant peer affiliation, and troubled families were independently associated with drug use. One in two students who used tobacco or alcohol had used these drugs in the past year (46% and 54%, respectively), and one in four students who used marijuana or cocaine in their lifetime had used those drugs in the past year (28% in both cases). CONCLUSION The rates of cocaine use as well as the proportion of current users were higher than expected among high school students and indicate changing patterns of drug use in Mexico. These results corroborate that the general trend of drug use by youth in Mexico is increasing. Results from this study help us better understand the needs of at-risk youth and the need for new treatment and prevention strategies.

Paraneoplastic limbic encephalitis is an autoimmune syndrome characterized by the acute or subacute onset of encephalopathy, memory loss, confusion, temporal lobe seizures, and behavioral and mood changes. Although most patients with paraneoplastic limbic encephalitis have antineuronal antibodies, advances in the field now permit the diagnosis without autoantibody test results. In this case illustrating the new diagnostic criteria, we report a 70-year-old woman who was brought to the emergency room after the acute onset of cognitive impairment, altered mental status, and choreoathetoid movements. Brain magnetic resonance imaging showed hyperintense signals in both temporal lobes, and a chest computed tomogram revealed a thymoma. Because the patient met current diagnostic criteria for autoimmune limbic encephalitis, we were able to start treatment before her antibody tests were processed. The patient received immunotherapy and her tumor was resected. Her choreoathetoid movements disappeared and her other neurologic symptoms improved. Her cerebrospinal fluid proved to be negative for paraneoplastic limbic encephalitis antibodies. Most but not all patients with paraneoplastic limbic encephalitis associated with thymoma have evidence of paraneoplastic antibodies. Prompt management of the underlying malignancy determines whether patients survive and may minimize future cognitive and functional impairment. Practicing neurologists and psychiatrists should be aware of this diagnosis.

The Arctic Alaska terrane of northern Alaska and Yukon is one of several exotic terranes in the North American Cordillera with putative early Paleozoic connections to the northern Caledonian-Appalachian orogen. The U-Pb and 40 Ar/ 39 Ar isotopic data from detrital minerals in pre-Mississippian sedimentary units of the northeastern Brooks Range are presented here to investigate the consequences of Caledonian orogenesis on sediment dispersal trends and the paleogeography of northern Laurentia. Neoproterozoic–Cambrian siliciclastic rocks of the informal Firth River group and the Neruokpuk Formation were most likely deposited along a passive margin that sourced Archean and Paleoproterozoic basement rocks of the Canadian shield and reworked Mesoproterozoic and younger sedimentary units. These strata are overlain by a Lower Ordovician–Lower Devonian succession of fine-grained siliciclastic turbidites, herein referred to as the Clarence River group, which records a prominent shift in provenance most likely associated with the onset of the Caledonian-Appalachian orogeny in northeast Laurentia. U-Pb detrital zircon age populations of ca. 470–420 and 990–820 Ma, along with 40 Ar/ 39 Ar detrital muscovite ages of ca. 470–430 Ma, support provenance connections with the East Greenland Caledonides, Pearya, and Svalbard. Partially reset 40 Ar/ 39 Ar ages in these sedimentary successions are linked to low-grade metamorphism associated with the Early–Middle Devonian Romanzof orogeny, a poorly understood tectonic event in the Brooks Range that is possibly associated with the emplacement of an allochthonous oceanic assemblage, herein named the Whale Mountain allochthon.

Mesozoic orogenic belts fringe the Alaska and eastern Russia portion of the Arctic Basin. From west to east, these include the fold belts of Novaya Zemlya, Taimyr Peninsula, northern Verkhoyansk–Kolyma, Chukotka and the Brooks Range, as well as their continuations onto the continental shelves. The Taimyr and Novaya Zemlya structures were traditionally interpreted as the continuation of the late Palaeozoic Uralian orogenic belt. This is probably correct for Taimyr, but not for Novaya Zemlya, where shortening post-dates Uralian deformation. The Mesozoic tectonic evolution of the Verkhoyansk–Kolyma, Chukotka and Brooks Range orogens relates to the accretion of numerous continental and arc terranes to the Siberian and North American margins starting in the Late Jurassic and driven by palaeo-Pacific dynamics. This history is complicated by the opening of the Amerasia Basin of the Arctic, which displaced the Arctic Alaska–Chukotka microplate from a position adjacent to Arctic Canada towards the palaeo-Pacific. Although the Chukotka fold belt and the Brooks Range both formed along the southern edge of Arctic Alaska–Chukotka, most shortening took place prior to Amerasia Basin opening. The remoteness of this region and the complexity of its geology has left numerous questions regarding its tectonic evolution unresolved, providing rich avenues for future research.

New U-Pb geochronology and a large and growing geochemical data base has clarified the age and composition of the extensive magmatic belts of NE Russia, allowing a better understanding of their relation to the plate tectonic evolution of the circum- Pacific margins of Russia, Alaska and the North American Cordillera, as well as to plate tectonic events that formed the Arctic Ocean. Prior to the magmatism described here, the paleo-Pacific margin of Siberia (now the Verkhoyansk-Kolyma orogen), Arctic Chukotka and the Brooks Range, Alaska, shared passive margin sedimentation from the Triassic to mid-Jurassic. Deformation along this once contiguous margin began with closure of deep-water basins and culminated with emplacement of oceanic and arc rocks onto the margin with continuing shortening of the margin into the Jura-Cretaceous. The Main Kolyma batholith belt (calc-alkaline granites to granodiorites) (158-144 Ma, peak 150±3 Ma) and the paired Uyandina-Yasachnaya volcanic arc are thought to have resulted from west-dipping subduction. Northern belt plutons (calc-alkaline) are 140-129 Ma and mostly post-date the E-W trending oroclinal bend of the northernVerkhoyansk fold belt. Calc-alkaline granites to granodiorites spanning 125-100 Ma intruded across Chukotka (Artic Russia) and Alaska during extension, right lateral shear and subduction zone retreat towards the Pacific perhaps coeval with the onset of rifting in the Amerasia Basin of the Arctic. The Uda-Murgal arc evolved independently along the Taigonos and Okhotsk part of the Russian margin, between 150-130 Ma and 107-97 Ma, and was followed by the establishment of the margin-parallel Okhotsk-Chukotka volcanic belt (OCVB), erupted in a neutral to slightly extensional tectonic regime, beginning 106 Ma, but, mostly between 98-80 Ma and ending ~ 76 Ma. Age equivalent magmatism in the Bering Strait is associated with continued extension, melting and remobilization of the deep crust. Between 80-60 Ma, subduction-related magmatism stepped south to the outer Bering Shelf and then to the Aleutians before 46 Ma. A similar process occurred in Russia with the pre-55 Ma onset of opening of the Sea of Okhotsk and step-wise migration of the subduction zone to eastern Kamchatka and Kuril Islands. These events broadly coincide with the opening of the Eurasia Basin of the Arctic. Profound differences occur in the tectonic setting of magmatism through time along strike of the subducting margin from Russia to the North American Cordillera. From 125 to 60 Ma, the NE Russian and Alaskan sectors of the margin underwent mostly neutral to extensional tectonism while the Cordillera underwent crustal shortening. Although vast amounts of paleo-Pacific oceanic lithosphere were subducted beneath both sectors of the margin, it appears that in a mantle reference frame, the Cordillera moved mostly towards its subduction zone while the overriding continental plates in NE Russia and Alaska moved parallel to or away from their subduction zones, allowing magmatism to take place in tectonically neutral or extensional settings. The coupled timing of trench-towards versus trench-away events related to motion of the overriding plates led to the observed “dance” of magmatism and deformation along the northern circum-Pacific margin.

A 22-year-old woman with tuberous sclerosis (TS) and an incomplete resection of a left-sided astrocytoma presented with a 4-year history of visual deterioration. Neurologic examination revealed a left relative afferent pupillary defect (RAPD) (video) with a pale left optic disc. Visual acuity was 20/100 bilaterally and a left-sided superior visual field loss was seen. Optical coherence tomography showed a left retinal hamartoma (figure 1). Contrast-enhanced brain MRI showed bilateral cortical and subcortical tubers (figure 2). Marcus-Gunn pupil or RAPD is a nonspecific feature denoting optic neuropathy.1 TS ophthalmopathy includes retinal and iris hamartomas, choroid colobomas, and hypopigmented lesions on iris and ciliary body.2

Development of unconventional shale gas wells can generate significant quantities of drilling waste, including trace metal-rich black shale from the lateral portion of the drillhole. We carried out sequential extractions on 15 samples of dry-drilled cuttings and core material from the gas-producing Middle Devonian Marcellus Shale and surrounding units to identify the host phases and evaluate the mobility of selected trace elements during cuttings disposal. Maximum whole rock concentrations of uranium (U), arsenic (As), and barium (Ba) were 47, 90, and 3333 mg kg−1, respectively. Sequential chemical extractions suggest that although silicate minerals are the primary host for U, as much as 20% can be present in carbonate minerals. Up to 74% of the Ba in shale was extracted from exchangeable sites in the shale, while As is primarily associated with organic matter and sulfide minerals that could be mobilized by oxidation. For comparison, U and As concentrations were also measured in 43 produced water samples returned from Marcellus Shale gas wells. Low U concentrations in produced water ( Geochemical modeling to determine mobility under surface storage and disposal conditions indicates that oxidation and/or dissolution of U-bearing minerals in drill cuttings would likely be followed by immobilization of U in secondary minerals such as schoepite, uranophane, and soddyite, or uraninite as conditions become more reducing. Oxidative dissolution of arsenic containing sulfides could release soluble As in arsenate form under oxic acidic conditions. The degree to which the As is subsequently immobilized depends on the redox conditions along the landfill flow path. The results suggest that proper management of drill cuttings can minimize mobilization of these metals by monitoring and controlling Eh, pH and dissolved constituents in landfill leachates.

The South Anyui suture zone consists of late Paleozoic–Jurassic ultramafic rocks and Jurassic–Cretaceous pre-, syn-, and postcollisional sedimentary rocks. It represents the closure of a Mesozoic ocean basin that separated two microcontinents in northeastern Russia, the Kolyma-Omolon block and the Chukotka block. In order to understand the geologic history and improve our understanding of Mesozoic paleogeography of the Arctic region, we obtained U-Pb ages on pre- and postcollisional igneous rocks and detrital zircons from sandstone in the suture zone. We identified four groups of sedimentary rocks: (1) Triassic sandstone deposited on the southern margin of Chukotka; (2) Middle Jurassic volcanogenic sandstone that was derived from the Oloy arc, a continental margin arc, along the Kolyma-Omolon block, south of the Anyui Ocean, a sample of which yielded no pre-Jurassic zircons and a single peak at 164 Ma; (3) suture zone sandstone that yielded Late Jurassic maximum depositional ages and likely predated the collision; and (4) a Mid-Cretaceous syncollisional sandstone that had a maximum depositional age of 125 Ma. These rocks were intruded by postkinematic plutons and dikes with ages of 109 Ma and 101 Ma that postdate the collision. We present a seismic-reflection line through the South Anyui suture zone that indicates south-vergence of thrusting of the Chukotka block over the Kolyma-Omolon block, opposite of most existing models and opposite of the vergence in the Angayucham suture zone, the postulated along-strike equivalent in Alaska. This suggests that Chukotka and Arctic Alaska may have different pre-Cretaceous histories, which could solve space problems with existing reconstructions of the Arctic region. We combine our detrital zircon data and interpretations of the seismic line to construct a new GPlates model for the Mesozoic evolution of the region that decouples Chukotka and Arctic Alaska to solve space problems with previous Arctic reconstructions.

The Mesoproterozoic–Neoproterozoic sedimentary succession of the eastern part of the Siberian Craton consists of several unconformity-bounded, kilometer-scale siliciclastic-carbonate cycles. The overlying Lower Cambrian rocks are often compositionally similar to the uppermost units of the Neoproterozoic succession. Twenty-nine samples were collected for U–Pb detrital zircon study and 27 samples were analyzed for whole-rock Sm–Nd isotopes. In total, 1491 detrital zircon grains were dated and 1148 grains were selected for provenance interpretation. Samples from the Uchur and Aimchan groups only contain detrital zircons of Paleoproterozoic and Archean age. Samples from the Kerpyl Group located on the Siberian Craton contain Paleoproterozoic and Archean grains as well, but samples from the Kerpyl Group in the Sette-Daban Ridge have significant numbers of Mesoproterozoic detrital zircons. Mesoproterozoic detrital zircons predominate in samples from the Uy Group. In the northern part of the study area, samples from the uppermost Neoproterozoic and Lower Cambrian strata contain numerous ca. 790–590 Ma detrital zircons, whereas in the southern part of the study area only Paleoproterozoic and Archean grains have been found. The whole-rock Sm–Nd isotopic values of clastic rocks show that most samples have isotopic signatures typical for the Siberian Craton basement, whereas some samples from the Kerpyl Group and younger rock units have isotopic signatures typical of the Grenville Orogen. Most of the Archean and Paleoproterozoic detrital zircons were eroded from the basement of the Siberian Craton, although some ca. 2080–2030 Ma detrital zircons are likely to have a non-Siberian provenance. However, rocks younger than ca. 1700 Ma are not known in the Siberian Craton basement and all Mesoproterozoic and younger grains must therefore have a non-Siberian provenance. The detrital zircon age distributions and whole-rock Nd isotopic signatures of many samples from the Kerpyl Group and younger units are very close to those of the Grenville Orogen in North America, suggesting that erosion of the latter contributed to clastic deposition along the Siberian margin. Three paleocontinental restorations proposed by Sears and Price (1978, 2003), Rainbird et al. (1998) and Pisarevsky and Natapov (2003) are invoked to explain the occurrence of Grenville-age detrital zircons in the Siberian sedimentary succession. The provenance of ca. 790–590 Ma detrital zircons is most likely to be located within the Central Taimyr accretionary belt formed along the northern margin of the Siberian Craton in the Neoproterozoic.

The utility of Prognostics and Health Management (PHM) software capability applied to Autonomous Operations (AO) remains an active research area within aerospace applications. The ability to gain insight into which assets and subsystems are functioning properly, along with the derivation of confident predictions concerning future ability, reliability, and availability, are important enablers for making sound mission planning decisions. When coupled with software that fully supports mission planning and execution, an integrated solution can be developed that leverages state assessment and estimation for the purposes of delivering autonomous operations. The authors have been applying this integrated, model-based approach to the autonomous loading of cryogenic spacecraft propellants at Kennedy Space Center.

Introduction: Chronic recurrent multifocal osteomyelitis (CRMO) is a very rare disease, of unknown origin that affects primarily the metaphysis of long bones. It is characterized by an insidious onset of symptoms and multiple remissions. The chronicity of symptoms, the diagnostic imaging and the lack of response to first line antibiotic treatment, should be helpful for diagnostic. Objective: Present a clinical case, based on clinical, laboratory, radiologic imaging and histopathological results, that ultimately led to the diagnostic of CRMO. Case Report: A 9 year old, female patient, with one month of bilateral knee and left ankle arthralgia. Bone Gammagraphy and full body MRI, showed multifocal bone inflammation. These findings led to a biopsy, that turned negative for malignancy and infection. Given all the information available from the laboratory test results, radiologic imaging and histopathological findings, CRMO diagnosis was made. NSAID treatment was order, with good results. Conclusions: CRMO is a rare disease that even to date and with cutting edge technology, still represents a diagnostic challenge that primarily relies on a high level of suspicion, for a timely and correct treatment.

In the Bendeleben Mountains, Seward Peninsula, mid-Cretaceous granites are exposed in an uplifted block bounded on its south side by an E-W striking normal fault. The Bendeleben fault has well-preserved scarps 4–7 m in height that offset Holocene moraines. Seismic activity, young normal faulting, and Quaternary basaltic volcanism are all evidence of active extension. South of the Bendeleben fault, there is a 3–4 km deep basin. Fifteen apatite (U-Th)/He ages from granitic samples of the footwall yield an Eocene weighted mean age of 41.3±4.8 Ma. Biotite 40Ar/39Ar ages from the country rock of the Bendeleben pluton are 81–83 Ma. In spite of the young fault scarps, HeFTy and Pecube thermal modeling results illustrate that rapid exhumation of the Bendeleben Mountains occurred in the Late Cretaceous-Eocene and slowed since the Oligocene. A weak age-elevation relationship of apatite He ages and a lack of correlation between age and distance from the fault indicate that exhumation was accomplished with minimal block rotation on a steeply dipping, long-lived normal fault. Timing of extension in the Seward Peninsula can be correlated with deformation in the offshore Hope Basin where seismic reflection lines document Early Tertiary large-magnitude normal faulting followed by minor post-Miocene reactivation. The faulting observed in the Bendeleben Mountains is part of an extensional system that spans a large portion of the Bering Strait region. The tectonic model proposed in previous studies suggests that clockwise rotation of the Bering block relative to North America is the cause of extensional deformation in western Alaska.

Several studies have explored the effect of the presence of medical students on patient satisfaction. However, nearly all of these studies took place in hospitals where medical students had been involved in patient care for many years. Less is known about patients' perceptions of care in a hospital moving toward becoming a teaching facility with undergraduate students. No research has explored patient satisfaction before and after the introduction of medical students.To assess patient satisfaction as an indicator of quality of care (QoC) from the patients' perspective, before and after the presence of medical students in a general hospital setting.This observational, cross-sectional study was conducted at Hospital Universitario-Fundación Santa Fe de Bogotá (HU-FSFB) in Bogotá, Colombia. The study had two phases. In 2006, prior to HU-FSBF becoming a teaching hospital, 385 subjects were asked to fill out a closed-question questionnaire addressing patients' satisfaction and perception of QoC provided by attending physicians. During the second period in 2009, 372 patients answered the same questionnaire when medical students were involved in their care.Patients' perceptions of QoC provided by attending physicians improved in five aspects when medical students were present: friendliness (p = 0.003), competence providing medical care (p = 0.049), quality of information provided (p = 0.025), amount of time spent with the patient (p 0.001) and availability to personally provide care (p 0.001). Overall patient satisfaction also significantly increased (p 0.001).The presence of medical students does not negatively affect patients' perceptions of QoC, on the contrary, these results provide evidence of improved patient satisfaction in several aspects of care when medical students were involved. The relevance of this study lies in its unique way of comparing patient satisfaction before and after the introduction of medical students. This setting helps elucidate the real effect of the presence of medical students on patient satisfaction.

There are few reports of the multiple cranial neuropathy variant of Guillain-Barré Syndrome (GBS). Patients usually present with facial diplegia, lower cranial nerve involvement and hypo or areflexia. It is crucial to identify promptly this unusual cranial variant but the clinical characteristics remain poorly defined. This GBS variant usually has a rapid progressive course with respiratory muscle paralysis. Most of the patients recover well, although the process is slow. We report a 54 year old man presenting with facial diplegia, progressive ophthalmoplegia, lower cranial nerve involvement, sensory ataxia and generalized areflexia. This GBS variant is very unusual and seldom described in the literature; it is oftenly misdiagnosed. The clinical features and nerve conduction studies (absent F-waves, motor conduction block) provide evidence to support a diagnosis of an acute demyelinating polyneuropathy consistent with a regional cranial variant of GBS.

Detrital zircon U–Pb ages from Triassic strata exposed in the circum-Arctic, analyzed by LA-ICP-MS and SHRIMP-RG, are compared at the regional scale to better understand the paleogeography of northern Pangea and help restore rift opening of the Arctic. Data sets are compared based on their zircon age distributions, cumulative age probability plots, and the K–S test. Three major source regions are characterized. These fed clastic material to transcontinental river systems that transported material from the highlands of northwestern Pangea to its once continuous paleo-Pacific continental margin. The paleo-Lena River System was fed from sources in the Baikalian and Altay-Sayan mountainous regions of Siberia. Zircon populations are characterized by a limited number of Precambrian zircons (~ 1.8–2.0 Ga with fewer ~ 2.5–3.0 Ga), lack of 0.9–1.8 Ga zircons, and a dominant 480–500 Ma and 290–300 Ma age population. The paleo-Taimyr River System was sourced from the Uralian orogenic belt region and deposited along a rifted portion of the Siberia–Baltica margin beginning in the Permo–Triassic. Precambrian zircon populations are similar to those of the paleo-Lena system, and samples closest to Siberia have similar populations in the 480–500 Ma and 290–300 Ma age ranges. Chukotka, Wrangel Island and Lisburne Hills, Alaska, have sparse ages between 900 and 1800 Ma, Ordovician ages are younger (~ 440–450 Ma), and, along with abundant ~ 300 Ma ages, they contain ~ 250–260 Ma and lesser ~ 215–235 Ma zircons, interpreted as derived from silicic volcanic centers associated with Permo–Triassic to Triassic continental flood basalt provinces in Siberia, Taimyr and Kara Sea region. The trans-Laurentian River System was likely fed by rift-related uplift along the proto North Atlantic/Arctic margin and delivered sediment to the Cordilleran margin of Pangea. These samples have no significant upper Paleozoic zircons and have a much broader age range of Precambrian zircons.