Electron-phonon coupling enhancement and displacive magnetostructural transition in SrCr2 As2 under magneto-Raman spectroscopy

A Raman spectroscopy study on high quality single crystals of SrCr₂ As₂ (SCA) in the temperature T range 4 K < T < 300 K and high applied magnetic fields up to H = 9 T is presented. The chromium B _1g phonon analysis reveals two anomalous shifts in the frequency, the first below T = 250 K at H = 0 T in the saturated AFM G-type order likely due to an enhanced electron-phonon coupling by the magnetic order, whereas the second anomaly occurs above H = 4 T at T = 4 K likely as a consequence of a magnetostructural displacive transition. Renormalization of the electronic Raman spectra in both studies reveals a decrease in the electronic density of states with decreasing T and increasing H, respectively, with consequent changes in the Fermi surface, which are intrinsically related to the observed anomalies.

Combined exercise training improves specific domains of cognitive functions and metabolic markers in middle-aged and older adults with type 2 diabetes mellitus

AIM

To investigate the effects of 8-weeks of CT on specific domains of cognitive function, metabolic and cardiovascular parameters of subjects with Type 2 Diabetes Mellitus (T2DM).

METHODS

31 sedentary T2DM adults and older divided into CT (3x/week, during 8-week, n = 16) or Control group (CONT, n = 15). Before and after the intervention, a cognitive task battery, blood samples, and functional tests were assessed.

RESULTS

CT improved inhibitory control (d = 0.89), working memory (d = 0.88), cognitive flexibility (d = 0.67) and attention/concentration (d = 0.64) in T2DM subjects. However, memory, verbal fluency, and processing speed (d < 0.1, p > 0.05 for all) were not changed. The CT-induced improvements on global cognitive z-score (r = -0.51; p < 0.001) were inversely correlated to cognitive screening scores. Moreover, CT improved functional performance (p < 0.05) and reduced insulin levels (p = 0.04). Although there was no statistical significance, there were a clinically relevant reduction of peripheral insulin sensitivity (d = 0.51, p = 0.09), resistin levels (d = 0.53, p = 0.08), diastolic (d = 0.63, p = 0.09) and mean blood pressure (d = 0.50, p = 0.09). Conversely, no changes were observed for glucose, fructosamine and blood lipids (d < 0.2 for all).

CONCLUSION

CT partially reversed the negative effects of T2DM on specific cognitive domains possibly by amelioration of metabolic regulation. Moreover, lower cognitive scores may modulate the responsivity of cognitive function to CT.

Spatial carrier distribution in InP/GaAs type II quantum dots and quantum posts

We performed a detailed investigation of the structural and optical properties of multi-layers of InP/GaAs quantum dots, which present a type II interface arrangement. Transmission electronic microscopy analysis has revealed relatively large dots that coalesce forming so-called quantum posts when the GaAs layer between the InP layers is thin. We observed that the structural properties and morphology affect the resulting radiative lifetime of the carriers in our systems. The carrier lifetimes are relatively long, as expected for type II systems, as compared to those observed for single layer InP/GaAs quantum dots. The interface intermixing effect has been pointed out as a limiting factor for obtaining an effective spatial separation of electrons and holes in the case of single layer InP/GaAs quantum-dot samples. In the present case this effect seems to be less critical due to the particular carrier wavefunction distribution along the structures.

Cervical spine alignment and hyoid bone positioning with temporomandibular disorders

The relationships between temporomandibular joint (TMJ) disorders and cervical structure dysfunctions have already been demonstrated. The aim of the present study was to investigate functional and structural alterations of the head and neck of 17 individuals with TMJ disorders (TMD group), compared with a control group of 17 asymptomatic subjects in a cross-sectional design. The outcome variables included pain on palpation of the sternocleidomastoideus, superior trapezius and subocciptal muscles, as well as radiographic measures of alignment of the cervical spine and positioning of the hyoid bone. Cervical alignment, determined by measures of the cervical curvature angle, was investigated by the Cobb method. Independent Student t-tests were used to investigate differences between groups for all outcome variables (alpha < 0.05). The results demonstrated that individuals with TMJ disorders, when compared with asymptomatic subjects, presented higher levels of perception of pain in all cervical muscles (P < 0.0001). No significant differences were found between groups for the cervical alignment measures. In the TMD group, the position of the hyoid bone in relation to the cervical spine did not appear to be different from the control group.