Academic literature on the topic 'MCA-3000'

Background Endovascular coil embolization of pial arteriovenous fistulas (AVF) has been reported as an effective treatment. However, venous thrombosis and intracranial hemorrhage developing after endovascular occlusion of a pial AVF have not been adequately reported. Case description A 37-year-old man presented with left middle cerebral artery (MCA) AVF and right posterior cerebral artery (PCA) AVF with giant venous pouches. Staged endovascular coil embolization was performed. The MCA AVF was completely occluded by coils at the first stage. Intravenous heparin (3000 IU) was administered during the procedure, and then low molecular weight heparin (subcutaneous injection, 0.4 mL/12 hours) was administered for two days. The PCA AVF was near completely occluded by coils without anticoagulation therapy at the second stage. Rapid progressive venous thrombosis and intracranial hemorrhage were confirmed by computerized tomography brain scan postoperatively, and the patient was then transferred to the neurological intensive care unit for further treatment. Finally, the patient recovered well at the five-month follow-up. Conclusions Endovascular occlusion of a high-flow pial AVF with a giant venous pouch resulting in significant blood stasis could precipitate thrombosis in the venous system. Further studies are required to establish whether anticoagulation therapy is necessary.

Mineral magnetic studies of Holocene lake sediments recovered from Zaca Lake, in coastal southern California have yielded a 3000-year high-resolution record of terrestrial hydrologic variability and paleolimnology. Samples for magnetic analysis were obtained from an 8.73 m core recovered from the central region of Zaca Lake. Ages, constrained using a combined paleomagnetic and radiocarbon chronostratigraphy, yield sedimentation rates of 2–10 mm/yr with an average rate of 3 mm/yr over the 3000-year interval. Parameters reflecting decadal-scale variability in magnetic concentration (susceptibility, ARM, SIRM) and grain size (ARM/Chi) were measured every 2 cm. Additional rock magnetic tests on whole rock samples and magnetic separates indicate that magnetite and an iron sulfide are the chief magnetic carriers. Detailed analysis of the rock magnetic record reveals four major temporal intervals: 0–135 cm (~AD 2009–1757) the period of European settlement; 135–270 cm (~AD 1757–1275) the period of Native American, Chumash occupation of the watershed encompassing the bulk of the wet interval known as the little ice age (LIA); 270–600 cm (AD 1275–100) encompassing the drier Medieval Climate Anomaly (MCA); and 600–875 cm (2000–3000 ybp) an era dominated by a long interval of low magnetic mineral intensity and concentration that has been interpreted as a time of epic drought. Beginning with the cessation of drought conditions at Zaca Lake around ~2000 ybp, the magnetic proxy record of rock magnetic cyclicity and hydrologic variability shows a pronounced decadal to centennial-scale periodicity. We interpret these periodicities as oscillations between summer-dominated sedimentary sequences, characterized by whiting events with their resulting carbonate deposits, and winter dominated sedimentary sequences, typified by sulfide-rich clastics, reflecting lacustrine overturn and enhanced advection of detrital flux during winter storm events. The long-term variation of summer versus winter-dominated weather patterns reflects the climate variability of central California coast-ranges.

BackgroundThe use of periprocedural heparin has previously been reported to be safe and potentially beneficial during thrombectomy with older generation devices. We aimed to evaluate the safety and clinical outcomes of heparin use in the stent retriever era.MethodsA post hoc analysis of the TREVO 2 trial was performed comparing baseline characteristics and clinical outcomes between patients who received (HEP+) and those who did not receive periprocedural heparin (HEP−) while undergoing MERCI or TREVO clot retrieval.ResultsOf 173 patients, 58 (34%) received periprocedural heparin including 40 who received one preprocedural bolus (median 3000 units). Baseline characteristics among HEP+ and HEP− patients were similar except HEP+ patients had a lower NIH Stroke Scale (NIHSS) score (17 vs 19; p=0.04), lower IV tissue plasminogen activator use (38% vs 64%; p<0.01), and a higher median ASPECTS score (8.0 vs 7.0; p=0.02). HEP+ patients were more likely to have vertebrobasilar and middle cerebral artery (MCA)-M1 occlusions but less likely to have internal carotid artery and MCA-M2 occlusions (p=0.04). Time from symptom onset to puncture was similar in the two groups while procedure duration was longer in HEP+ patients (99 vs 83 min; p<0.01). Thrombolysis In Cerebral Infarction (TICI) 2b–3 reperfusion rates, embolization to unaffected territories, access site complications, and intracranial hemorrhages were similar between the groups. In multivariable logistic regression, a good outcome (90-day modified Rankin Scale score 0–2) was independently associated with heparin bolus use (OR 5.30; 95% CI 1.70 to 16.48), TICI 2b–3 reperfusion (OR 6.56; 95% CI 2.29 to 18.83), stent retriever use (OR 3.54; 95% CI 1.38 to 9.03) and inversely associated with intubation (OR 0.10; 95% CI 0.03 to 0.33), diabetes (OR 0.11; 95% CI 0.03 to 0.39), NIHSS (OR 0.84; 95% CI 0.75 to 0.93), time from symptom onset to puncture (OR 0.64; 95% CI 0.45 to 0.89), and heart failure (OR 0.23; 95% CI 0.06 to 0.83).ConclusionsThe use of periprocedural heparin in stent retriever thrombectomy is associated with a good clinical outcome at 90 days and similar rates of symptomatic intracranial hemorrhage. Further studies are warranted.Clinical trial registrationURL:http://www.clinicaltrials.gov. Unique identifier: NCT01270867; Post-results.

Several important North American coastal conifers – having immigrated during the Holocene from the southeast – reach their northern and upper elevation limits in south-central Alaska. However, our understanding of the specific timing of migration has been incomplete. Here, we use two new pollen profiles from a coastal and a high-elevation site in the Eastern Kenai Peninsula–Prince William Sound region, along with other published pollen records, to investigate the Holocene biogeography and development history of the modern coastal Picea (spruce)– Tsuga (hemlock) forest. Tsuga mertensiana became established at Mica Lake (100 m elevation, near Prince William Sound) by 6000 cal. BP and at Goat Lake (550 m elevation in the Kenai Mountains) sometime after 3000 years ago. Tsuga heterophylla was the last major conifer to arrive in the region. Although driven partially by climate change, major vegetation changes during much of the Holocene are difficult to interpret exclusively in terms of climate, with periods of slow migration alternating with more rapid movement. T. mertensiana expanded slowly northeastward in the early Holocene, compared with Picea sitchensis or T. heterophylla. Difficulty of invading an already established conifer forest may account for this. We suggest that during the early Holocene, non-climatic factors as well as proximity to refugia, influenced rates of migration. Climate may have been more important after ~2600 cal. BP. Continued expansion of T. mertensiana at Goat Lake at the Medieval Climate Anomaly (MCA)–‘Little Ice Age’ (‘LIA’) transition suggests warm and wet winters. But expansion of T. mertensiana at both sites was arrested during the colder climate of the ‘LIA’. The decline was more extensive at Goat Lake, where climatic conditions may have been severe enough to reduce or eliminate the T. mertensiana population. T. mertensiana continued its expansion around Goat Lake after the ‘LIA’.

Background Arterial transit time correction by data acquisition with multiple post-labeling delays (PLDs) or relatively long PLDs is expected to obtain more accurate imaging in cases of the cerebrovascular steno-occlusive disease. However, there have so far been no reports describing the significance of arterial spin labeling (ASL) images at short PLDs regarding the evaluation of cerebral circulation in ischemic cerebrovascular disease. Purpose To clarify the role of short-PLD ASL in cerebrovascular steno-occlusive disease. Material and Methods Fifty-three patients with cerebrovascular steno-occlusive disease were included in this study. All patients underwent ASL magnetic resonance imaging and 15O-PET within two days of each modality. To compare the ASL findings with each parameter of PET, the right-to-left (R/L) ratio, defined as the right middle cerebral artery (MCA) value/left MCA value, was calculated. Results There is a significant correlation between the ASL images at a short PLD and the ratio of cerebral blood flow and cerebral blood volume by 15O-PET, which may accurately reflect the cerebral perfusion pressure. A receiver operating characteristic curve analysis indicated that ASL images at PLD 1000 and 1500 ms were more accurate than at PLD 2000–3000 ms for the detection of a ≥10% change in the PET cerebral blood flow. Conclusion ASL images at shorter PLDs may be useful at least as a screening modality to detect the changes in the cerebral circulation in cerebrovascular steno-occlusive disease. We must evaluate ASL images at multiple PLDs while considering the arterial transit time of each case at present.

Introduction: New imaging markers employing sophisticated models of tissue microstructure may lead to better understanding of neurobiological substrates in childhood arterial ischemic stroke. Methods: Four children with acute unilateral MCA territory ischemic stroke were retrospectively included [two males, age range 2 -16 years]. Parameters of two complementary diffusion modeling techniques: Neurite Orientation Dispersion and Density Imaging (NODDI), and Spherical Mean Technique (SMT) were estimated using two-shell diffusion data acquired at presentation ( b- values = 1000 and 3000 s/mm 2 ). For comparison, diffusion tensor imaging (DTI) parameters were also estimated. Parameter estimates were derived from the acute infarct-affected gray matter, the reconstructed pyramidal tract and the contra-hemispheric homologs. Contrast-to-noise ratios (CNRs) were calculated for each pair of homologous brain regions. Results: In both the acute infarct-affected gray matter, and pyramidal tracts, the multi-shell parameter estimates demonstrated increased intra-cellular volume fraction (F icvf and INVF in figure), predominant reduced extra-cellular microscopic diffusivity (ENMMD and ENTMD in figure), and increased orientation dispersion of the infarct-affected axonal fibers (ODI in figure). These findings were consistent with respective acute stroke histopathological features of cytotoxic edema, narrowed extracellular spaces, and axonal swelling. The CNRs were associated with stroke severity and motor function outcome at follow-up. Conclusion: The parameter estimates derived from multi-shell diffusion data produces robust infarct contrast, and provides histopathologically plausible imaging biomarkers representing brain microstructural changes in acute childhood stroke. Routine clinical introduction of this imaging technique requires further elucidations of its prognostic values in predicting stroke severity and/or motor outcomes.

A 3300 year-long reconstruction of paleoenvironmental moisture conditions was constructed from a sediment core from North Gate Bog (NGB) in the northern section of Range Creek Canyon within the Colorado Plateau. The methods used to analyze the record include loss on ignition (LOI), magnetic susceptibility (MS), elemental analysis with X-ray fluorescence (XRF), charcoal influx, isotopic analysis, elemental ratios and pollen percentages, influx, and ratios. This study adds two new insights to the paleoenvironmental record of the northern section of the Colorado Plateau. First, four climatic zones were established. Zone 1 (3300–2750 cal yr BP) had 100-year wet to dry variations with droughts recorded from 3300–3200, 3000–2900, and 2800–2700 cal yr BP. Zone 2 (2750–1600 cal yr BP) had an overall dry period with an 800-year transition to increased warmth and winter moisture. Zone 3 (1600–850 cal yr BP) had an overall warm, wet, summer precipitation climate conducive to the establishment of Zea Mays and Pinus edulis, two staple foods of the Fremont culture. The Medieval Climate Anomaly (MCA) registered warm and wet in this part of the Colorado Plateau. Zone 4 (850–0 cal yr BP) had a sharp transition to a drier climate from 850 to 400 cal yr BP. During the Little Ice Age (LIA), wetter climate taxon increases such as Artemisia, Cyperaceae, and Pinus edulis. The second overall finding in this study was that NGB was a place of human activity including Fremont farming. The identification of a Zea mays pollen grain confirms the archeological presumptions that this higher elevation site was used to farm corn along with other sites in Range Creek Canyon (RCC). The post Fremont occupation period was marked by a sharp increase in organic material and a return of pinyon-juniper woodlands.

Purpose: Compaction is one of the fundamental pillars of construction, without a proper compaction of ground material deformation may occur shorty after completed construction. A flaw of the traditional method of compaction control is that only point sources are obtained. This means that you can easily miss weak points of the compaction. This becomes significant when dealing with compaction of larger areas. The purpose of this study is to investigate how digital technology can ensure the compaction quality compared to traditional methods, and to expand the company’s knowledge of the application of the compaction computer MCA-3000. Method: The method chosen to gather data for this study were literature study, case study and interviews. Findings: The findings show how the compaction computer can be used to ensure compaction quality. An important factor is to know the conditions of the ground material in order to ensure a credible result. The case study suggest that the compaction computer can be used to visually show the compaction quality of an area. However, I cannot be used as a separated method to ensure compaction quality. The compaction computer needs test surfaces to be calibrated with assistance of traditional methods. This means that it cannot replace the traditional method. However, it can be used as a complementary tool to support the traditional methods. In the interviews, both the respondents pointed out that the compaction computer cannot be used as a separate method but can be used as a complementary tool for the contractors.  Implications: Our conclusions are as followed: ·         The compaction computer cannot be used as a single method to ensure compaction quality. ·         The compaction computer implies that it can be used as a complementary tool to support the traditional methods to ensure compaction quality of lager areas.  ·         The compaction computer allows the user to detect faults in real time during the compaction prosses. Our results indicate that the compaction computer can be uses as a complementary tool to support the traditional methods but not as its own method. To ensure the reliability of the compaction computer MCA-3000 further studies needs to be conducted to see how it preform with different ground material condition.  Limitations: Our result was limited by access of data. We were only able to collet data from a single project in a relatively small area, this means we only were able to get three data sources of compaction quality conducted with a tradition method. Another limitation was that the entire area had the same ground condition which means the result is only applicable in our case.