Manganese-enhanced MRI of hypoxic-ischemic brain injuries using Mn-DPDP

Theme: Engineering the Future of BiomedicineIn this study, Mn-dipyridoxaldiphosphate (MnDPDP), a clinically approved manganese contrast agent for hepatic and pancreatic imaging, was demonstrated for the first time for manganese-enhanced MRI (MEMRI) in brains of normal young rats (n=4) and rats with hypoxic-ischemic (H-I) insult at postnatal day 7 (n=8). After a single intraperitoneal injection of low dosage with 0.1μmol/g in postnatal 14 days, 2D T1-weighted image (T1WIs), T1 maps, T2-weighted images (T2WIs) and T2 maps were acquired at 7 Tesla 1 day before, 1 day and 7 days after MnDPDP injection. The image contrast changes induced by MnDPDP appeared as the hyperintensity in T1WIs and the hypointensity in T2WIs. T1and T2 values decreased in the regions of Mn enhancement. Such enhancement presented as a delayed pattern that was more pronounced in 7 day after MnDPDP injection, suggesting the sustained Mn accumulation due to MnDPDP. Moreover, the MnDPDP enhancement in H-I brains was more pronounced in the lesion sites and was easily detectable in T1WI, T1 map, T2WI and T2 map. The results demonstrated here support the possibility of using MnDPDP as a 'slow release' Mn2+ for clinical diagnosis of various neuropathologies. ©2009 IEEE.published_or_final_versionThe 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2009), Minneapolis, MN., 3-6 September 2009. In Proceedings of the 31st EMBC, 2009, p. 4775-477

Free-breathing 2D time-of-flight pulmonary MRA at 3T

This study aims to optimize and evaluate a free-breathing 2D TOF PMRA protocol at 3T. The protocol was based on a T1-weighted turbo field echo sequence with static tissue suppression using magnetization transfer plus selective inverse recovery, spectral fat saturation, cardiac gating, respiratory navigator gating, and parallel imaging. Satisfactory pulmonary MRAs were demonstrated in volunteer subjects (N=12). The proposed protocol is clinically relevant for patients who are unable to provide long breath-holds during MRI scans.published_or_final_versio

Magnetic resonance imaging of migrating neuronal precursors in normal and hypoxic-ischemic neonatal rat brains by intraventricular MPIO labeling

Proceedings of the IEEE Engineering in Medicine and Biology Society Conference, 2008, p. 363-366In this study, 10-day-old normal rats (n=6) and hypoxic-ischemic (H-I) neonatal rats (n=6) were injected with the micronsized iron oxide particles (MPIOs) into the anterior lateral ventricle. 2D and 3D high-spatial resolution MRI were performed with a 7T animal scanner 1 day before the MPIOs injection and hour 3, day 3, day 7 and day 14 after the MPIOs injection. Intraperitoneal injections of 5-bromo-2'-deoxyuridine (BrdU) were used to label newly produced cells, and were given thrice daily for 2 days before sacrifice. Immunohistochemistry and Prussian blue staining indicated that iron particles were inside the nestin+ and BrdU+ neural progenitor cells (NPCs), glial-fibrillary-acidic-protein-positive (GFAP+) astrocytes-like progenitor cells, and neuronal-nuclei-positive (NeuN+) mature neurons. Here we demonstrate that, in normal neonatal rat brain, the migrating pathway of the endogenous NPCs with MPIO is mainly along the rostral migratory stream to the olfactory bulb. In H-I neonatal rat brain, the migration of endogenous NPCs with MPIO is mainly towards the ischemic regions. Therefore, in vivo magnetic cell labeling of endogenous NPCs with MPIO and subsequently non-invasive, serial MRI monitoring should open up a new approach to probe into the mechanism of cell migration in the developmental brain under physiological and pathologic conditions. © 2008 IEEE.published_or_final_versio

MRI characterization of trabecular bone structure by exploring bone microscopic susceptibility effect

Bone strength depends on bone mineral density (BMD) as well as properties related to bone quality, such as the microarchitecture of trabecular bone. Structural parameters, such as trabecular thickness, can also critically influence the mechanical competence and thus resistance to fracture of bone. Complex bone structure can induce microscopic susceptibility effect and alter the bone transverse relaxation properties, which are expected to become more prominent at high field. This study aims to examine such susceptibility effect at 3T and explore the possibility of using bone as an endogenous contrast agent to derive the structural information in human trabecular bone.published_or_final_versio

MOTSA TOF-MRA using multi-oblique-stacks acquisition (MOSA)

One of the intrinsic advantages of current TOF MRA techniques is their insensitivity to in-plane blood flow or turbulent flow, causing hypointense signal or discontinuity in blood vessels in MRA images. To overcome this problem, a multi-oblique-stacks acquisition (MOSA) technique is proposed to improve the visualization of in-plane blood flows in MRA. The results showed that TOF-MRA obtained from MOSA was improved as compared to that of conventional MOTSA for the same amount of scan time.published_or_final_versio

The Complete Calibration of the Color-Redshift Relation (C3R2) Survey: Survey Overview and Data Release 1

A key goal of the Stage IV dark energy experiments Euclid, LSST and WFIRST is to measure the growth of structure with cosmic time from weak lensing analysis over large regions of the sky. Weak lensing cosmology will be challenging: in addition to highly accurate galaxy shape measurements, statistically robust and accurate photometric redshift (photo-z) estimates for billions of faint galaxies will be needed in order to reconstruct the three-dimensional matter distribution. Here we present an overview of and initial results from the Complete Calibration of the Color-Redshift Relation (C3R2) survey, designed specifically to calibrate the empirical galaxy color-redshift relation to the Euclid depth. These redshifts will also be important for the calibrations of LSST and WFIRST. The C3R2 survey is obtaining multiplexed observations with Keck (DEIMOS, LRIS, and MOSFIRE), the Gran Telescopio Canarias (GTC; OSIRIS), and the Very Large Telescope (VLT; FORS2 and KMOS) of a targeted sample of galaxies most important for the redshift calibration. We focus spectroscopic efforts on under-sampled regions of galaxy color space identified in previous work in order to minimize the number of spectroscopic redshifts needed to map the color-redshift relation to the required accuracy. Here we present the C3R2 survey strategy and initial results, including the 1283 high confidence redshifts obtained in the 2016A semester and released as Data Release 1.Comment: Accepted to ApJ. 11 pages, 5 figures. Redshifts can be found at http://c3r2.ipac.caltech.edu/c3r2_DR1_mrt.tx

Joint Hybrid Precoder and Combiner Design for mmWave Spatial Multiplexing Transmission

Millimeter-wave (mmWave) communications have been considered as a key technology for future 5G wireless networks because of the orders-of-magnitude wider bandwidth than current cellular bands. In this paper, we consider the problem of codebook-based joint analog-digital hybrid precoder and combiner design for spatial multiplexing transmission in a mmWave multiple-input multiple-output (MIMO) system. We propose to jointly select analog precoder and combiner pair for each data stream successively aiming at maximizing the channel gain while suppressing the interference between different data streams. After all analog precoder/combiner pairs have been determined, we can obtain the effective baseband channel. Then, the digital precoder and combiner are computed based on the obtained effective baseband channel to further mitigate the interference and maximize the sum-rate. Simulation results demonstrate that our proposed algorithm exhibits prominent advantages in combating interference between different data streams and offer satisfactory performance improvement compared to the existing codebook-based hybrid beamforming schemes

Cosmological Horizons, Uncertainty Principle and Maximum Length Quantum Mechanics

The cosmological particle horizon is the maximum measurable length in the Universe. The existence of such a maximum observable length scale implies a modification of the quantum uncertainty principle. Thus due to non-locality of quantum mechanics, the global properties of the Universe could produce a signature on the behaviour of local quantum systems. A Generalized Uncertainty Principle (GUP) that is consistent with the existence of such a maximum observable length scale $l_{max}$ is $\Delta x \Delta p \geq \frac{\hbar}{2}\;\frac{1}{1-\alpha \Delta x^2}$ where $\alpha = l_{max}^{-2}\simeq (H_0/c)^2$ ($H_0$ is the Hubble parameter and $c$ is the speed of light). In addition to the existence of a maximum measurable length $l_{max}=\frac{1}{\sqrt \alpha}$, this form of GUP implies also the existence of a minimum measurable momentum $p_{min}=\frac{3 \sqrt{3}}{4}\hbar \sqrt{\alpha}$. Using appropriate representation of the position and momentum quantum operators we show that the spectrum of the one dimensional harmonic oscillator becomes $\bar{\mathcal{E}}_n=2n+1+\lambda_n \bar{\alpha}$ where $\bar{\mathcal{E}}_n\equiv 2E_n/\hbar \omega$ is the dimensionless properly normalized $n^{th}$ energy level, $\bar{\alpha}$ is a dimensionless parameter with $\bar{\alpha}\equiv \alpha \hbar/m \omega$ and $\lambda_n\sim n^2$ for $n\gg 1$ (we show the full form of $\lambda_n$ in the text). For a typical vibrating diatomic molecule and $l_{max}=c/H_0$ we find $\bar{\alpha}\sim 10^{-77}$ and therefore for such a system, this effect is beyond reach of current experiments. However, this effect could be more important in the early universe and could produce signatures in the primordial perturbation spectrum induced by quantum fluctuations of the inflaton field.Comment: 11 pages, 7 Figures. The Mathematica file that was used for the production of the Figures may be downloaded from http://leandros.physics.uoi.gr/maxlenqm

Is "Better Data" Better than "Better Data Miners"? (On the Benefits of Tuning SMOTE for Defect Prediction)

We report and fix an important systematic error in prior studies that ranked classifiers for software analytics. Those studies did not (a) assess classifiers on multiple criteria and they did not (b) study how variations in the data affect the results. Hence, this paper applies (a) multi-criteria tests while (b) fixing the weaker regions of the training data (using SMOTUNED, which is a self-tuning version of SMOTE). This approach leads to dramatically large increases in software defect predictions. When applied in a 5*5 cross-validation study for 3,681 JAVA classes (containing over a million lines of code) from open source systems, SMOTUNED increased AUC and recall by 60% and 20% respectively. These improvements are independent of the classifier used to predict for quality. Same kind of pattern (improvement) was observed when a comparative analysis of SMOTE and SMOTUNED was done against the most recent class imbalance technique. In conclusion, for software analytic tasks like defect prediction, (1) data pre-processing can be more important than classifier choice, (2) ranking studies are incomplete without such pre-processing, and (3) SMOTUNED is a promising candidate for pre-processing.Comment: 10 pages + 2 references. Accepted to International Conference of Software Engineering (ICSE), 201