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•Compared single-band 3.3 mm, 2 mm and multiband factors 2, 3, 4, 6, 8, 9, 12 at 2 mm.•Multiband noise amplification creates spatial biases in rs-fMRI correlations.•Temporal filtering reduces spatial biases but decreases effect sizes.•Single-band 3.3 mm recommended for seed-based analyses involving subcortical regions.•Multiband 4 is a good choice for whole-brain analyses with 2 mm isotropic voxels. [Display omitted] Multiband acquisition, also called simultaneous multislice, has become a popular technique in resting-state functional connectivity studies. Multiband (MB) acceleration leads to a higher temporal resolution but also leads to spatially heterogeneous noise amplification, suggesting the costs may be greater in areas such as the subcortex. We evaluate MB factors of 2, 3, 4, 6, 8, 9, and 12 with 2 mm isotropic voxels, and additionally 2 mm and 3.3 mm single-band acquisitions, on a 32-channel head coil. Noise amplification was greater in deeper brain regions, including subcortical regions. Correlations were attenuated by noise amplification, which resulted in spatially varying biases that were more severe at higher MB factors. Temporal filtering decreased spatial biases in correlations due to noise amplification, but also tended to decrease effect sizes. In seed-based correlation maps, left-right putamen connectivity and thalamo-motor connectivity were highest in the single-band 3.3 mm protocol. In correlation matrices, MB 4, 6, and 8 had a greater number of significant correlations than the other acquisitions (both with and without temporal filtering). We recommend single-band 3.3 mm for seed-based subcortical analyses, and MB 4 provides a reasonable balance for studies analyzing both seed-based correlation maps and connectivity matrices. In multiband studies including secondary analyses of large-scale datasets, we recommend reporting effect sizes or test statistics instead of correlations. If correlations are reported, temporal filtering (or another method for thermal noise removal) should be used. The Emory Multiband Dataset is available on OpenNeuro.

•Volitional control of ToM network observed.•Volitional control associated with thinking about social experiences.•Weak evidence that volitional control may impact behavior.•Potential applications to clinical groups with social difficulties. Is there a way improve our ability to understand the minds of others? Towards addressing this question, here, we conducted a single-arm, proof-of-concept study to evaluate whether real-time fMRI neurofeedback (rtfMRI-NF) from the temporo-parietal junction (TPJ) leads to volitional control of the neural network subserving theory of mind (ToM; the process by which we attribute and reason about the mental states of others). As additional aims, we evaluated the strategies used to self-regulate the network and whether volitional control of the ToM network was moderated by participant characteristics and associated with improved performance on behavioral measures. Sixteen participants underwent fMRI while completing a task designed to individually-localize the TPJ, and then three separate rtfMRI-NF scans during which they completed multiple runs of a training task while receiving intermittent, activation-based feedback from the TPJ, and one run of a transfer task in which no neurofeedback was provided. Region-of-interest analyses demonstrated volitional control in most regions during the training tasks and during the transfer task, although the effects were smaller in magnitude and not observed in one of the neurofeedback targets for the transfer task. Text analysis demonstrated that volitional control was most strongly associated with thinking about prior social experiences when up-regulating the neural signal. Analysis of behavioral performance and brain-behavior associations largely did not reveal behavior changes except for a positive association between volitional control in RTPJ and changes in performance on one ToM task. Exploratory analysis suggested neurofeedback-related learning occurred, although some degree of volitional control appeared to be conferred with the initial self-regulation strategy provided to participants (i.e., without the neurofeedback signal). Critical study limitations include the lack of a control group and pre-rtfMRI transfer scan, which prevents a more direct assessment of neurofeedback-induced volitional control, and a small sample size, which may have led to an overestimate and/or unreliable estimate of study effects. Nonetheless, together, this study demonstrates the feasibility of training volitional control of a social cognitive brain network, which may have important clinical applications. Given the study's limitations, findings from this study should be replicated with more robust experimental designs.

To examine resting-state functional MRI (rs-fMRI) networks related to sleep in the context of HIV infection. rs-fMRI data were collected in 40 HIV-infected (HIV+) individuals at baseline (treatment-naive), 12 week (post-treatment) and one year timepoints. A group of 50 age-matched HIV-negative (HIV-) individuals were also imaged at baseline and one year timepoints. The Pittsburgh Sleep Quality Index (PSQI) questionnaire was administered at all timepoints. Using group independent component analysis (ICA), maps of functional networks were generated from fMRI data; from these, sleep-related networks were selected. A generalized linear model (GLM) was used to analyze if these networks were significantly associated with the PSQI score, and if this relationship was influenced by HIV status/treatment or timepoint. HIV+ individuals had significantly lower PSQI score after treatment (p=0.022). Networks extracted from group ICA analysis included the anterior and posterior default mode network (DMN), central executive network (CEN), bilateral frontoparietal networks (FPNs), and the anterior cingulate cortex salience network (ACC SN). We found the posterior DMN, right FPN, and ACC SN GLMs showed significantly higher goodness-of-fit after incorporating PSQI data (p = 0.0204, 0.044, 0.044, respectively). Furthermore, the correlation between ACC SN and posterior DMN connectivity was significantly decreased in the HIV+ cohort. Functional networks such as the DMN, FPN, CEN, and ACC SN are altered in poor sleep, as measured by the PSQI score. Furthermore, the relationship between these networks and PSQI is different in the HIV+ and HIV- populations.

Accelerated imaging in diffusion MRI has been widely used to reduce scan time. This can be particularly important in reducing the burden in patients, such as those with mild cognitive impairment (MCI). However, the impact on reliability is not fully understood. Moreover, the impact on effect sizes in group comparisons has not been examined. We conducted a test–retest study of the impact of simultaneous multislice (SMS, also called multiband) and in‐plane acceleration (IPA, also called phase acceleration) on reliability and effect sizes in diffusion imaging in MCI, healthy older adults, and young adults. We evaluated diffusion tensor imaging measures (fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) and neurite orientation and dispersion measures (orientation dispersion, isotropic volume fraction, intracellular volume fraction) under no acceleration (S1P1), SMS = 3 with no in‐plane acceleration (S3P1), SMS = 3 with IPA = 2 (S3P2), S6P1, and S6P2, with scan times varying from over 20 min in S1P1 to under 4 min in S6P2. In white matter voxels, the ranking of the accelerations with respect to intraclass correlations (ICCs) was S1P1 ≈ $$ \\approx $$S3P1 ≥ $$ \\ge $$S3P2 > $$ > $$S6P1 > $$ > $$S6P2, with ICCs in the good range across most DWI measures in S1P1, S3P1, and S3P2, moderate to good in S6P1, and poor to moderate in S6P2. In‐plane acceleration did not improve ICC in areas of high susceptibility distortion. Acceleration significantly impacted the values of white matter microstructure with an overall trend of increase in fractional anisotropy and decrease in orientation dispersion with increasing multiband acceleration. In group comparisons, effect sizes tended to be similar across S1P1, S3P1, S3P2, and S6P1, including medium effect sizes in MCI versus healthy older adults and large effect sizes in young versus healthy older adults. Our results provide guidance regarding the costs of acceleration (reduced ICC from high acceleration) while also characterizing the benefits (S3P1 has similar reliability as S1P1 while requiring one third of the acquisition time, ROI‐level group comparisons similar between S1P1, S3P1, S3P2, and S6P1). The overall high reliability and medium effect sizes of white matter microstructure measures with a moderate SMS factor indicates accelerated DWI can be used in developing biomarkers of neurological decline. Comparing multiband factors (S = 1, 3, 6) and in‐plane acceleration factors (P = 1, 2) in diffusion‐weighted imaging, S3P1 has good reliability, similar to no acceleration. S3P2 is competitive. Acceleration alters diffusion metrics. Effect sizes comparing mild cognitive impairment, older adults, and young adults in S1P1, S3P1, S3P2, and S6P1 were generally similar.

Satellite tracking of animals has advantages in the study of species that migrate across international borders, have large home ranges and occupy remote and inaccessible areas. The efficacy of this technology in dense tropical forests may, however, be limited. At the same time, its use in mitigating wildlife–human conflict has not been examined so far. Here we report the movement patterns and habitat utilization of an adult male Asian elephant, and a preliminary assessment of the potential use of satellite technology as an 'early warning system' for conflict mitigation. Data on the location of the animal were obtained from a Platform Transmitter Terminal mounted on an elephant in Jaldapara, West Bengal, the first if its kind used on this species in India. We found that the animal preferred forest and forest plantations during the day, making visits to cultivated lands at night. There was some predictability in the movement of this animal, suggesting that similar technologies such as the more advanced Global Positioning System can be used for near 'real-time tracking' of problem elephants.

Diffusion MRI (dMRI) is a modality used to probe diffusion of water molecules in the brain. In the brain, the process of diffusion is intimately connected to the cellular microstructure. Therefore, any changes to this microstructure is captured by dMRI, which ash made it a mainstay in imaging of pathology such as stroke and multiple sclerosis. With technological and software advances, dMRI sensitivity has improved and new representations of white matter integrity are being actively explored. With these advances, the amount and quality of data needed has grown, the end result being longer acquisition time requirements and a greater reliance on individual scan parameters. In this thesis, we explore the impact of dMRI parameters on data quality and reconstruction with the context that adequate selection of parameters will allow us to reduce scan time while maintaining data integrity. To this end, we have three sections in our thesis: the first section contains background information relating to neuroanatomy and MRI physics, the second section covers the theory and methods implemented in our thesis, and the third and final section contains applications of our theory and methods. In general, dMRI parameters can be separated into those related to diffusion-encoding and those related to imaging. Parameters of the former include b-values and b-vectors and the latter contains image acceleration. The b-values and b-vector control how strongly and in which direction we are sensitized to the diffusion process, respectively. In this thesis, we investigate the influence of these parameters on dMRI reconstruction and speculate about sparse sampling of b-vectors to reduce imaging time while accurately reconstructing white matter tracts. In the imaging domain, we investigate the effect of slice and phase acceleration, two parameters that reduce scan time, on data quality and reconstruction. At each step, we make recommendations on parameter selection. We conclude with an application of our methods on real datasets. We test our sparse sampling of b-vectors on a group of subjects with traumatic brain injury to elucidate how well a sparse sample can capture disease effects. For the imaging application, we investigate how acceleration parameters influence our ability to distinguish a group of subjects with mild cognitive impairment and a healthy group.

Spotted deer or chital (Axis axis), a major prey species in southern India, lives in large groups. To understand the benefits of group living, we carried out observations on chital herds under natural conditions. Individual and group vigilance showed a negative correlation with herd size, whereas the latter had a positive correlation with proportion of vigilant individuals. Furthermore, individual vigilance was negatively correlated with proportion of individuals vigilant and positively correlated with group vigilance. These results are explained in the context of a threephase vigilance system, probably operative in the chital herd, under specified ecological conditions. We surmise that this system allows for adaptation to predation risk and has possibly co-evolved with the optimal hunting strategy of the predator.

Solar radio observations provide a powerful diagnostic of the physical conditions of the solar atmosphere over a wide range of heights. In this paper, we report regular solar mapping made at the X-band (8.1 – 9.2 GHz) with the Arecibo 12-m radio telescope, covering a period between 13 December 2021 and 9 April 2023. This has demonstrated its potential for identifying active regions and tracking their brightness-temperature changes. The X-band results are discussed along with the near-simultaneous datasets available from space- and ground-based observations. A comparison of magnetic properties of active regions with their emission characteristics indicates that the X-band brightness temperature provides better information of the magnetic-field strength associated with the emission and a brightness temperature in excess of 13 000 K allows us to infer the possibility of intense flares (i.e., ≳ M1 class) and coronal mass ejections. The ‘latitude–time’ distribution of the brightness temperature reveals the three-dimensional evolution of quiet regions on the Sun, coronal holes, and eruptive sites, over many solar rotations in the ascending phase of the current Solar Cycle 25.

Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass ([Formula: see text]) companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk, or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 ± 0.04 [Formula: see text], an unusually high value.

Spotted deer or chital (Axis axis), a major prey species in southern India, lives in large groups. To understand the benefits of group living, we carried out observations on chital herds under natural conditions. Individual and group vigilance showed a negative correlation with herd size, whereas the latter had a positive correlation with proportion of vigilant individuals. Furthermore, individual vigilance was negatively correlated with proportion of individuals vigilant and positively correlated with group vigilance. These results are explained in the context of a three phase vigilance system, probably operative in the chital herd, under specified ecological conditions. We surmise that this system allows for adaptation to predation risk and has possibly co-evolved with the optimal hunting strategy of the predator.