Atmospheric circulation and cyclone frequency variations linked to the primary modes of Greenland snow accumulation

Data from 34 Greenland firn cores, extending from 1982 to 1996, are used to identify spatial accumulation variability patterns and their associated atmospheric circulation and cyclone frequencies. The first principal component, representing west-central Greenland accumulation, is correlated to NAO variability, having increased southwesterly (northeasterly) flow over that area during high (low) accumulation winters. The flow is linked to a relative increase in cyclone activity on the west central region of the ice sheet during high accumulation periods. The second principal component represents accumulation over southeastern Greenland where strong westerly flow leads to high accumulation and an increase in lee cyclones on the east and southeast coast. The study provides evidence that increased cyclone activity occurs over, or immediately adjacent to, areas experiencing anomalously high accumulation and it is important to distinguish lee cyclones from ‘‘Icelandic’’ cyclones, as they produce opposite precipitation effects over the ice sheet

Physical Aggression and Mindfulness among College Students: Evidence from China and the United States

The link between trait mindfulness and several dimensions of aggression (verbal, anger and hostility) has been documented, while the link between physical aggression and trait mindfulness remains less clear. Method: We used two datasets: one United States sample from 300 freshmen males from Clemson University, South Carolina and a Chinese sample of 1516 freshmen students from Shanghai University of Finance and Economics. Multiple regressions were conducted to examine the association between mindfulness (measured by Mindful Attention and Awareness Scale (MAAS)) and each of the four subscales of aggression. Results: Among the Clemson sample (N = 286), the mindfulness scale had a significant negative association with each of the four subscales of aggression: Hostility: β = −0.62, p \u3c 0.001; Verbal: β = −0.37, p \u3c 0.001; Physical: β = −0.29, p \u3c 0.001; Anger: β = −0.44, p \u3c 0.001. Among the Shanghai male subsample, the mindfulness scale had a significant negative association with each of the four subscales of aggression: Hostility: β = −0.57, p \u3c 0.001; Verbal: β = −0.37, p \u3c 0.001; Physical: β = −0.35, p \u3c 0.001; Anger: β = −0.58, p \u3c 0.001. Among the Shanghai female subsample (N = 512), the mindfulness scale had a significant negative association with each of the four subscales of aggression: Hostility: β = −0.62, p \u3c 0.001; Verbal: β = −0.41, p \u3c 0.001; Physical: β = −0.52, p \u3c 0.001; and Anger: β = −0.64, p \u3c 0.001. Discussion: Our study documents the negative association between mindfulness and physical aggression in two non-clinical samples. Future studies could explore whether mindfulness training lowers physical aggression among younger adults

Diverging volumetric trajectories following pediatric traumatic brain injury.

Traumatic brain injury (TBI) is a significant public health concern, and can be especially disruptive in children, derailing on-going neuronal maturation in periods critical for cognitive development. There is considerable heterogeneity in post-injury outcomes, only partially explained by injury severity. Understanding the time course of recovery, and what factors may delay or promote recovery, will aid clinicians in decision-making and provide avenues for future mechanism-based therapeutics. We examined regional changes in brain volume in a pediatric/adolescent moderate-severe TBI (msTBI) cohort, assessed at two time points. Children were first assessed 2-5 months post-injury, and again 12 months later. We used tensor-based morphometry (TBM) to localize longitudinal volume expansion and reduction. We studied 21 msTBI patients (5 F, 8-18 years old) and 26 well-matched healthy control children, also assessed twice over the same interval. In a prior paper, we identified a subgroup of msTBI patients, based on interhemispheric transfer time (IHTT), with significant structural disruption of the white matter (WM) at 2-5 months post injury. We investigated how this subgroup (TBI-slow, N = 11) differed in longitudinal regional volume changes from msTBI patients (TBI-normal, N = 10) with normal WM structure and function. The TBI-slow group had longitudinal decreases in brain volume in several WM clusters, including the corpus callosum and hypothalamus, while the TBI-normal group showed increased volume in WM areas. Our results show prolonged atrophy of the WM over the first 18 months post-injury in the TBI-slow group. The TBI-normal group shows a different pattern that could indicate a return to a healthy trajectory

A Model for Transient Oxygen Delivery in Cerebral Cortex

Popular hemodynamic brain imaging methods, such as blood oxygen-level dependent functional magnetic resonance imaging (BOLD fMRI), would benefit from a detailed understanding of the mechanisms by which oxygen is delivered to the cortex in response to brief periods of neural activity. Tissue oxygen responses in visual cortex following brief visual stimulation exhibit rich dynamics, including an early decrease in oxygen concentration, a subsequent large increase in concentration, and substantial late-time oscillations (“ringing”). We introduce a model that explains the full time-course of these observations made by Thompson et al. (2003). The model treats oxygen transport with a set of differential equations that include a combination of flow and diffusion in a three-compartment (intravascular, extravascular, and intracellular) system. Blood flow in this system is modeled using the impulse response of a lumped linear system that includes an inertive element; this provides a simple biophysical mechanism for the ringing. The model system is solved numerically to produce excellent fits to measurements of tissue oxygen. The results give insight into the dynamics of cerebral oxygen transfer, and can serve as the starting point to understand BOLD fMRI measurements