Mild Acceleration Research Articles

MicroRNA-140 Provides Robustness to the Regulation of Hypertrophic Chondrocyte Differentiation by the PTHrP-HDAC4 Pathway.

Growth plate chondrocytes go through multiple differentiation steps and eventually become hypertrophic chondrocytes. The parathyroid hormone (PTH)-related peptide (PTHrP) signaling pathway plays a central role in regulation of hypertrophic differentiation, at least in part, through enhancing activity of histone deacetylase 4 (HDAC4), a negative regulator of MEF2 transcription factors that drive hypertrophy. We have previously shown that loss of the chondrocyte-specific microRNA (miRNA), miR-140, alters chondrocyte differentiation including mild acceleration of hypertrophic differentiation. Here, we provide evidence that miR-140 interacts with the PTHrP-HDAC4 pathway to control chondrocyte differentiation. Heterozygosity of PTHrP or HDAC4 substantially impaired animal growth in miR-140 deficiency, whereas these mutations had no effect in the presence of miR-140. miR-140-deficient chondrocytes showed increased MEF2C expression with normal levels of total and phosphorylated HDAC4, indicating that the miR-140 pathway merges with the PTHrP-HDAC4 pathway at the level of MEF2C. miR-140 negatively regulated p38 mitogen-activated protein kinase (MAPK) signaling, and inhibition of p38 MAPK signaling reduced MEF2C expression. These results demonstrate that miR-140 ensures the robustness of the PTHrP/HDAC4 regulatory system by suppressing MEF2C-inducing stimuli. © 2014 American Society for Bone and Mineral Research © 2015 American Society for Bone and Mineral Research.

Improved measurement of brain deformation during mild head acceleration using a novel tagged MRI sequence

In vivo measurements of human brain deformation during mild acceleration are needed to help validate computational models of traumatic brain injury and to understand the factors that govern the mechanical response of the brain. Tagged magnetic resonance imaging is a powerful, noninvasive technique to track tissue motion in vivo which has been used to quantify brain deformation in live human subjects. However, these prior studies required from 72 to 144 head rotations to generate deformation data for a single image slice, precluding its use to investigate the entire brain in a single subject. Here, a novel method is introduced that significantly reduces temporal variability in the acquisition and improves the accuracy of displacement estimates. Optimization of the acquisition parameters in a gelatin phantom and three human subjects leads to a reduction in the number of rotations from 72 to 144 to as few as 8 for a single image slice. The ability to estimate accurate, well-resolved, fields of displacement and strain in far fewer repetitions will enable comprehensive studies of acceleration-induced deformation throughout the human brain in vivo.

Effect of increased initial ripening temperature on the sensory characteristics of Reggianito cheese

The effects of increased initial ripening temperature on the sensory characteristics of Reggianito cheese were evaluated in relation to different temperature–time combinations. Control cheeses stored at 12 °C for 6 months and experimental cheeses stored at 20 °C for 2 or 4 weeks then at 12 °C up to 6 months were analysed at 61, 124, and 180 days of ripening by physicochemical, microbiological and quantitative descriptive analysis. The use of an initial increased ripening temperature results in controlled and limited changes on mesophilic lactobacilli growth and in a mild acceleration of the sensory characteristic development of Reggianito cheese.

In vivo lung morphometry with accelerated hyperpolarized (3) He diffusion MRI: a preliminary study.

Parallel imaging can be used to reduce imaging time and to increase the spatial coverage in hyperpolarized gas magnetic resonance imaging of the lung. In this proof-of-concept study, we investigate the effects of parallel imaging on the morphometric measurement of lung microstructure using diffusion magnetic resonance imaging with hyperpolarized (3) He. Fully sampled and under-sampled multi-b diffusion data were acquired from human subjects using an 8-channel (3) He receive coil. A parallel imaging reconstruction technique (generalized autocalibrating partially parallel acquisitions [GRAPPA]) was used to reconstruct under-sampled k-space data. The morphometric results of the generalized autocalibrating partially parallel acquisitions-reconstructed data were compared with the results of fully sampled data for three types of subjects: healthy volunteers, mild, and moderate chronic obstructive pulmonary disease patients. Morphometric measurements varied only slightly at mild acceleration factors. The results were largely well preserved compared to fully sampled data for different lung conditions. Parallel imaging, given sufficient signal-to-noise ratio, provides a reliable means to accelerate hyperpolarized-gas magnetic resonance imaging with no significant difference in the measurement of lung morphometry from the fully sampled images. GRAPPA is a promising technique to significantly reduce imaging time and/or to improve the spatial coverage for the morphometric measurement with hyperpolarized gases.

D-brane bremsstrahlung

We study the dynamics of ultrarelativistic D-branes. The dominant phenomenon is bremsstrahlung: mild acceleration induced by closed string interactions triggers extremely rapid energy loss through radiation of massless closed strings. After characterizing bremsstrahlung from a general k-dimensional extended object in a D-dimensional spacetime, we incorporate effects specific to D-branes, including velocity-dependent forces and open string pair creation. We then show that dissipation due to bremsstrahlung can substantially alter the dynamics in DBI inflation.

Brain morphometry reproducibility in multi-center 3 T MRI studies: A comparison of cross-sectional and longitudinal segmentations

Large-scale longitudinal multi-site MRI brain morphometry studies are becoming increasingly crucial to characterize both normal and clinical population groups using fully automated segmentation tools. The test–retest reproducibility of morphometry data acquired across multiple scanning sessions, and for different MR vendors, is an important reliability indicator since it defines the sensitivity of a protocol to detect longitudinal effects in a consortium. There is very limited knowledge about how across-session reliability of morphometry estimates might be affected by different 3T MRI systems. Moreover, there is a need for optimal acquisition and analysis protocols in order to reduce sample sizes. A recent study has shown that the longitudinal FreeSurfer segmentation offers improved within session test–retest reproducibility relative to the cross-sectional segmentation at one 3T site using a nonstandard multi-echo MPRAGE sequence. In this study we implement a multi-site 3T MRI morphometry protocol based on vendor provided T1 structural sequences from different vendors (3D MPRAGE on Siemens and Philips, 3D IR-SPGR on GE) implemented in 8 sites located in 4 European countries. The protocols used mild acceleration factors (1.5–2) when possible. We acquired across-session test–retest structural data of a group of healthy elderly subjects (5 subjects per site) and compared the across-session reproducibility of two full-brain automated segmentation methods based on either longitudinal or cross-sectional FreeSurfer processing. The segmentations include cortical thickness, intracranial, ventricle and subcortical volumes. Reproducibility is evaluated as absolute changes relative to the mean (%), Dice coefficient for volume overlap and intraclass correlation coefficients across two sessions. We found that this acquisition and analysis protocol gives comparable reproducibility results to previous studies that used longer acquisitions without acceleration. We also show that the longitudinal processing is systematically more reliable across sites regardless of MRI system differences. The reproducibility errors of the longitudinal segmentations are on average approximately half of those obtained with the cross sectional analysis for all volume segmentations and for entorhinal cortical thickness. No significant differences in reliability are found between the segmentation methods for the other cortical thickness estimates. The average of two MPRAGE volumes acquired within each test–retest session did not systematically improve the across-session reproducibility of morphometry estimates. Our results extend those from previous studies that showed improved reliability of the longitudinal analysis at single sites and/or with non-standard acquisition methods. The multi-site acquisition and analysis protocol presented here is promising for clinical applications since it allows for smaller sample sizes per MRI site or shorter trials in studies evaluating the role of potential biomarkers to predict disease progression or treatment effects.

Impact of experimental haemodilution on platelet function, thrombin generation and clot firmness: effects of different coagulation factor concentrates.

Haemodilution during resuscitation after massive haemorrhage may worsen the coagulopathy and perpetuate bleeding. Blood samples from healthy donors were diluted (30 and-60%) using crystalloids (saline, Ringer's lactate, Plasmalyte(TM)) or colloids (6% hydroxyethylstarch [HES130/0.4], 5% human albumin, and gelatin). The effects of haemodilution on platelet adhesion (Impact R), thrombin generation (TG), and thromboelastometry (TEM) parameters were analysed as were the effects of fibrinogen, prothrombin complex concentrates (PCC), activated recombinant factor VII (FVIIa), and cryoprecipates on haemodilution. Platelet interactions was already significantly reduced at 30% haemodilution. Platelet reactivity was not improved by addition of any of the concentrates tested. A decrease in TG and marked alterations of TEM parameters were noted at 60% haemodilution. HES130/0.4 was the expander with the most deleterious action. TG was significantly enhanced by PCC whereas rFVIIa only caused a mild acceleration of TG initiation. Fibrinogen restored the alterations of TEM parameters caused by haemodilution including those caused by HES 130/0.4. Cryoprecipitates significantly improved the alterations caused by haemodilution on TG and TEM parameters; the effects on TG disappeared after ultracentrifugation of the cryoprecipitates. The haemostatic alterations caused by haemodilution are multifactorial and affect both blood cells and coagulation. In our in vitro approach, HES 130/0.4 had the most deleterious effect on haemostasis parameters. Coagulation factor concentrates did not improve platelet interactions in the Impact R, but did have favourable effects on coagulation parameters measured by TG and TEM. Fibrinogen notably improved TEM parameters without increasing thrombin generation, suggesting that this concentrate may help to preserve blood clotting abilities during haemodilution without enhancing the prothrombotic risk.

Natural variation in the temperature range permissive for vernalization in accessions of Arabidopsis thaliana

Vernalization is an acceleration of flowering in response to chilling, and is normally studied in the laboratory at near-freezing (2-4 °C) temperatures. Many vernalization-requiring species, such as Arabidopsis thaliana, are found in a range of habitats with varying winter temperatures. Natural variation in the temperature range that elicits a vernalization response in Arabidopsis has not been fully explored. We characterized the effect of intermediate temperatures (7-19 °C) on 15 accessions and the well-studied reference line Col-FRI. Although progressively warmer temperatures are gradually less effective at activating expression of the vernalization-specific gene VERNALIZATION-INSENSITIVE 3 (VIN3) and in accelerating flowering, there is substantial natural variation in the upper threshold (T(max) ) of the flowering-time response. VIN3 is required for the T(max) (13 °C) response of Col-FRI. Surprisingly, even 16 °C treatment caused induction of VIN3 in six tested lines, despite the ineffectiveness of this temperature in accelerating flowering for two of them. Finally, we present evidence that mild acceleration of flowering by 19 °C exposure may counterbalance the flowering time delay caused by non-inductive photoperiods in at least one accession, creating an appearance of photoperiod insensitivity.

Preparation and characterization of quasi-solid-state electrolytes using a brominated poly(2,6-dimethyl-1,4-phenylene oxide) electrospun nanofiber mat for dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are prepared with quasi-solid-state electrolytes by employing electrospun nanofiber mats. Here, we investigated the effects of a brominated poly(phenylene oxide) (BPPO) electrospun nanofiber mat used as a non-fluorinated polymer backbone in DSSCs. It was found that BPPO, which contains ether and bromine functional groups of non-bonding electrons, acts as a Lewis base. This Lewis basicity not only negatively shifted the flat band, but also coordinated Li ions in the electrolyte. As a result, by introducing a quasi-solid-state electrolyte, the open circuit voltage increased by 50 mV and the photon-to-current efficiency was comparable to a conventional liquid electrolyte. Furthermore, the quasi-solid-state DSSCs exhibited enhanced long-term stability, maintaining 97% of initial efficiency after 7 d under a mild acceleration condition at 50 °C.

Principal Component Analysis of Dynamic Relative Displacement Fields Estimated from MR Images

Non-destructive measurement of acceleration-induced displacement fields within a closed object is a fundamental challenge. Inferences of how the brain deforms following skull impact have thus relied largely on indirect estimates and course-resolution cadaver studies. We developed a magnetic resonance technique to quantitatively identify the modes of displacement of an accelerating soft object relative to an object enclosing it, and applied it to study acceleration-induced brain deformation in human volunteers. We show that, contrary to the prevailing hypotheses of the field, the dominant mode of interaction between the brain and skull in mild head acceleration is one of sliding arrested by meninges.

Repair of persistent truncus arteriosus without a conduit: sleeve resection of the pulmonary trunk from the aorta and direct right ventricle-pulmonary artery anastomosis☆

Establishing a new continuity between the right ventricle and the pulmonary artery is the mainstay of repair for persistent truncus arteriosus. We used the Tran Viet-Neveux technique without a Lecomte maneuver to construct the connection without a conduit. Here, we retrospectively review the mid-term surgical results to examine the effectiveness of this approach. A cylindrical segment incorporating both pulmonary artery branches was sleeve-resected from the truncal artery. The cylindrical segment was cut in the middle and two truncal arterial flaps were combined to form the posterior floor of the new pulmonary arterial trunk. The edge of the floor was attached directly to the superior margin of an oblique incision made in the left-anterior wall of the right ventricle. A polytetrafluoroethylene monocusp was attached to the lower half margin of the right ventricular incision. A large glutaraldehyde-treated pericardial patch was used to form the anterior hood of the new right ventricular outflow tract. Both great arteries were located in a normal spiral configuration. Ten babies (range: 3 days to 9 months of age) underwent this procedure. The Collett-Edwards classification of persistent truncus arteriosus was type I in five cases and type II in five others. There was one hospital death due to severe respiratory distress. During follow-up (36-60 months, median 54 months), only one re-operation was required to enlarge a left branch pulmonary artery stenosis. Follow-up echocardiography showed pulmonary regurgitation (mild two, moderate seven, and severe one) and mild flow acceleration in the left pulmonary artery branch and right ventricle-pulmonary artery connection in one case. This simple modification for surgical correction of persistent truncus arteriosus may be an effective alternative that overcomes conduit-related problems.

A New Technique for Interrupted Aortic Arch Repair: The Neville Tube

We have developed a new technique for interrupted aortic arch repair in which the pulmonary artery anterior wall is cut off and tailored so as to re-establish aortic continuity with an autologous tube. We are describing this method herein, with an 8-year follow-up of the first patient.

Bose-Einstein condensation in the early universe

By introducing the Bose-Einstein condensation dynamics (BEC), we develop a unified model of dark energy and dark matter. The two phases of BEC (= dark energy) and normal gas (= dark matter) transform with each other through the phase transition. We study the present mild acceleration, the inflation in the early universe, and the reduction of the cosmological constant. We find the stagflation regime when the cosmic expansion stops and the uniform mode of BEC becomes unstable. We also comment on the possibility that BEC generation/decay series might have continued all the time in the cosmic history from the inflation to present.

Bose‐Einstein condensation in the early universe

AbstractBy introducing the Bose‐Einstein condensation dynamics (BEC), we develop a unified model of dark energy and dark matter. The two phases of BEC (= dark energy) and normal gas (= dark matter) transform with each other through the phase transition. We study the present mild acceleration, the inflation in the early universe, and the reduction of the cosmological constant. We find the stagflation regime when the cosmic expansion stops and the uniform mode of BEC becomes unstable. We also comment on the possibility that BEC generation/decay series might have continued all the time in the cosmic history from the inflation to present.

Letter by Hamilton-Craig et al Regarding Article, “Posttraumatic Cardiac Contrecoup: In Vivo Evidence by Cardiac Magnetic Resonance Imaging”

To the Editor: We propose an alternative explanation to the findings reported by Moccetti et al.1 First, numerous biomechanical explanations of contrecoup injury have been proposed, such as the positive pressure, negative pressure, rotational shear stress, and angular acceleration theories.2,3 These theories relate to transmission of the deceleration force to a soft organ from the surrounding hard structures (eg, brain–skull, lung–ribs). The injury described …

Stagflation: Bose-Einstein condensation in the early universe

Our universe experienced the accelerated expansion at least twice; an extreme inflationary acceleration in the early universe and the recent mild acceleration. By introducing the Bose-Einstein condensation (BEC) phase of a boson field, we have been developing a unified model of dark energy (DE) and dark matter (DM) for the later mild acceleration. In this scenario, two phases of BEC (=DE) and normal gas (=DM) transform with each other through BEC phase transition. This unified model has successfully explained the mild acceleration as an attractor. We extend this BEC cosmology to the early universe without introducing new ingredients. In this scenario, the inflation is naturally initiated by the condensation of the bosons in the huge vacuum energy. This inflation and even the cosmic expansion eventually terminates exactly at zero energy density. We call this stage as stagflation. At this stagflation era, particle production and the decay of BEC take place. The former makes the universe turn into the standard hot big bang stage and the latter makes the cosmological constant vanishingly small after the inflation. Furthermore, we calculate the density fluctuations produced in this model, which turns out to be in the range allowed by the present observational data. We also show that the stagflation is quite robust and easily appears when one allows negative region of the potential. Further, we comment on the possibility that BEC generation/decay series might have continued all the time in the cosmic history from the inflation to present.

Early clinical experience with the new amplatzer ductal occluder II for closure of the persistent arterial duct

To describe the early single-center clinical experience with the Amplatzer Ductal Occluder II (ADO II). All patients undergoing attempted transcatheter closure of persistent arterial duct (PDA) with the ADO II were included. Data collected included demographic, clinical, and echocardiographic parameters. From March until September 2008, 29 procedures were undertaken in 27 patients (21 female). Median age was 1.4 years (range 0.4-76 years) with median weight 9.4 kg (range 4.7-108 kg). A transarterial approach was used in 2 patients. The median minimum ductal diameter was 2.7 mm (range 1.7-5). ADO II was released in 25 patients (92.5%). Two patients had significant residual shunting following deployment of ADO II and underwent closure with Amplatzer ductal occluder (ADO I). Postprocedural echocardiography identified one occluder had changed position with development of a significant leak and one occluder had embolized to the left pulmonary artery. Both occluders were retrieved successfully at a second catheter procedure. Complete occlusion was noted predischarge in 22 of the remaining 23 occluders (96%). One patient had mild flow acceleration in the left pulmonary artery which has resolved. The ADO II is highly effective at providing rapid occlusion of morphologically varied PDAs. Occluder design allows closure with arterial or venous approach and delivery with 4 or 5 F delivery catheters. Stable occluder position is dependent on correct positioning of both aortic and pulmonary discs. A larger range of sizes and configurations of this occluder may be required to successfully occlude all ductal sizes and morphologies.

Environmental Impacts of Catalytic Converter Malfunctions

For effective reduction of total vehicle emissions, identifying and understanding the effects of high-emitting vehicles play an important role. Although several studies have documented the environmental impacts of high-emitting vehicles, these studies have not looked at the operational impacts of these vehicles on the environment. In this study, field-collected and simulated data are used to explain the operational effects associated with catalytic converter malfunctions on vehicle emissions. In addition, the study develops microscopic emission models for vehicles with catalytic converter malfunctions by using on-road emission measurement data. The study demonstrates that catalytic converter malfunctions produce significant increases in hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions of 297%, 211%, and 378%, respectively, during cruising operations. Furthermore, increases of 63.4%, 26.9%, and 76.1% are observed during acceleration maneuvers. The study also found that under extremely aggressive driving conditions, both normal and high-emitting vehicles produce very high emission rates. The simulation results demonstrate that the highest impact of catalytic converter malfunction occurs in the 45- to 85-km/h speed range at mild acceleration levels for HC and CO emissions and between 20 and 55 km/h at high acceleration levels for NOx emissions. Simulation analysis of various driving cycles demonstrates that catalytic converter malfunctions produce overall increases in HC, CO, and NOx emissions in the range of 251%, 225%, and 336%, respectively. The study demonstrates that high-emitting vehicles can be significant contributors to air pollution, implying that eliminating high-emitting vehicles could significantly improve air quality in many metropolitan areas.

Deformation of the human brain induced by mild angular head acceleration

Deformation of the human brain was measured in tagged magnetic resonance images (MRI) obtained dynamically during angular acceleration of the head. This study was undertaken to provide quantitative experimental data to illuminate the mechanics of traumatic brain injury (TBI). Mild angular acceleration was imparted to the skull of a human volunteer inside an MR scanner, using a custom MR-compatible device to constrain motion. A grid of MR “tag” lines was applied to the MR images via spatial modulation of magnetization (SPAMM) in a fast gradient echo imaging sequence. Images of the moving brain were obtained dynamically by synchronizing the imaging process with the motion of the head. Deformation of the brain was characterized quantitatively via Lagrangian strain. Consistent patterns of radial-circumferential shear strain occur in the brain, similar to those observed in models of a viscoelastic gel cylinder subjected to angular acceleration. Strain fields in the brain, however, are clearly mediated by the effects of heterogeneity, divisions between regions of the brain (such as the central fissure and central sulcus) and the brain's tethering and suspension system, including the dura mater, falx cerebri, and tentorium membranes.

The internal membranes of the human head protect the brain during impact

Deformation of the human brain was measured in tagged magnetic resonance images (MRI) obtained dynamically during angular acceleration of the head. This study was undertaken to provide quantitative experimental data to illuminate the mechanics of traumatic brain injury (TBI). Mild angular acceleration was imparted to the skull of a human volunteer inside an MR scanner, using a custom MR-compatible device to constrain motion. A grid of MR “tag” lines was applied to the MR images via spatial modulation of magnetization (SPAMM) in a fast gradient echo imaging sequence. Images of the moving brain were obtained dynamically by synchronizing the imaging process with the motion of the head. Deformation of the brain was characterized quantitatively via Lagrangian strain. Consistent patterns of radial-circumferential shear strain occur in the brain, similar to those observed in models of a viscoelastic gel cylinder subjected to angular acceleration. Strain fields in the brain, however, are clearly mediated by the effects of heterogeneity, divisions between regions of the brain (such as the central fissure and central sulcus) and the brain's tethering and suspension system, including the dura mater, falx cerebri, and tentorium membranes.