How do large and unique brains evolve? Historically, comparative neuroanatomical studies have attributed the evolutionary genesis of highly encephalized brains to deviations along, as well as from, ...conserved scaling relationships among brain regions. However, the relative contributions of these concerted (integrated) and mosaic (modular) processes as drivers of brain evolution remain unclear, especially in non-mammalian groups. While proportional brain sizes have been the predominant metric used to characterize brain morphology to date, we perform a high-density geometric morphometric analysis on the encephalized brains of crown birds (Neornithes or Aves) compared to their stem taxa—the non-avialan coelurosaurian dinosaurs and
Archaeopteryx
. When analyzed together with developmental neuroanatomical data of model archosaurs (
Gallus
,
Alligator
), crown birds exhibit a distinct allometric relationship that dictates their brain evolution and development. Furthermore, analyses by neuroanatomical regions reveal that the acquisition of this derived shape-to-size scaling relationship occurred in a mosaic pattern, where the avian-grade optic lobe and cerebellum evolved first among non-avialan dinosaurs, followed by major changes to the evolutionary and developmental dynamics of cerebrum shape after the origin of Avialae. Notably, the brain of crown birds is a more integrated structure than non-avialan archosaurs, implying that diversification of brain morphologies within Neornithes proceeded in a more coordinated manner, perhaps due to spatial constraints and abbreviated growth period. Collectively, these patterns demonstrate a plurality in evolutionary processes that generate encephalized brains in archosaurs and across vertebrates.
The evolution of flight is a rare event in vertebrate history, and one that demands functional integration across multiple anatomical/physiological systems. The neuroanatomical basis for such ...integration and the role that brain evolution assumes in behavioural transformations remain poorly understood. We make progress by (i) generating a positron emission tomography (PET)-based map of brain activity for pigeons during rest and flight, (ii) using these maps in a functional analysis of the brain during flight, and (iii) interpreting these data within a macroevolutionary context shaped by non-avian dinosaurs. Although neural activity is generally conserved from rest to flight, we found significant increases in the cerebellum as a whole and optic flow pathways. Conserved activity suggests processing of self-movement and image stabilization are critical when a bird takes to the air, while increased visual and cerebellar activity reflects the importance of integrating multimodal sensory information for flight-related movements. A derived cerebellar capability likely arose at the base of maniraptoran dinosaurs, where volumetric expansion and possible folding directly preceded paravian flight. These data represent an important step toward establishing how the brain of modern birds supports their unique behavioural repertoire and provide novel insights into the neurobiology of the bird-like dinosaurs that first achieved powered flight.
Synopsis Museum collections play a pivotal role in the advancement of biological science by preserving phenotypic and genotypic history and variation. Recently, contrast-enhanced X-ray computed ...tomography (CT) has aided these advances by allowing improved visualization of internal soft tissues. However, vouchered specimens could be at risk if staining techniques are destructive. For instance, the pH of unbuffered Lugol's iodine (I2KI) may be low enough to damage deoxyribonucleic acid (DNA). The extent of this risk is unknown due to a lack of rigorous evaluation of DNA quality between control and experimental samples. Here, we used formalin-fixed mice to document DNA concentrations and fragment lengths in nonstained, ethanol-preserved controls and 3 iodine-based staining preparations: (1) 1.25% weight-by-volume (wt/vol.) alcoholic iodine (I2E); (2) 3.75% wt/vol. I2KI; and (3) 3.75% wt/vol. buffered I2KI. We tested a null hypothesis of no significant difference in DNA concentrations and fragment lengths between control and treatment samples. We found that DNA concentration decreases because of staining—potentially an effect of measuring intact double-stranded DNA only. Fragment lengths, however, were significantly higher for buffered I2KI and control samples, which were not, themselves, significantly different. Our results implicate buffered I2KI as the appropriate choice for contrast-enhanced CT imaging of museum wet collections to safely maximize their potential for understanding genetic and phenotypic diversity.
We elucidate the key chemical and physical requirements necessary for the future successful design and fabrication of molecular field-effect devices. We show that the molecular assembly, device ...fabrication, and electrical measurements of reported self-assembled monolayer field-effect transistors (SAMFETs) cannot be reproduced. Carrier tunneling and device electrostatics place minimum molecular lengths of L > 2.5−3 nm and minimum gate dielectric thickness t dielectric ≲ L/1.5 for such devices. In conflict with reported SAMFET device characteristics, for the values of L and t dielectric in these structures, it is fundamentally impossible to either turn the devices off or to obtain a significant field-effect. Synthesis, assembly, and characterization of functionalized molecular systems and fabrication and characterization of appropriately scaled device structures may enable the successful preparation of a molecular field-effect transistor.
A constant current stress scheme is implemented for endurance study on OTS-PCM devices for the first time. It provides a feasible method to estimate the read/write endurance for cross-point PCM ...products, which can save testing time for chips qualification. A 256kb chip with 1E7 cycles is demonstrated that corresponds with the endurance evaluation on the doped AsGeSe OTS with doped Ge2Sb2Te5 system.
Electromigration mass flow in Cu damascene lines which were connected to W blocking barrier contacts and were capped with either a CoWP, Ta, Ta/TaN, Pd, SiN
x
, or SiC
x
N
y
H
z
layer was ...investigated. Cu lines, fabricated with body centered cubic α- or tetragonal β-Ta liners, were also investigated. A thin electroless CoWP, physical vapor deposition (PVD) Ta, PVD Pd or PVD Ta/TaN cap on top of the Cu line significantly reduced the interface diffusivity and remarkably improved the electromigration lifetime when compared with lines capped with SiN
x
or SiC
x
N
y
H
z
. Activation energies for electromigration in bamboo-like Cu lines were found to be 2 eV with a CoWP cap, 1.4 eV with a PVD Pd, Ta or Ta/TaN cap, and 0.9–1 eV with a SiC
x
N
y
H
z
or SiN
x
cap. The Ta phase was found to have an insignificant effect on the Cu mass flow rate, as did the Cu texture.
We present a scaling study toward lZnm node 3D Cross-point PCM (XPCM) for Storage Class Memory (SCM) applications. The low operation current, and low metal line loading resistance are desired to ...avoid a wide operation voltage distribution in a cross-point array. For the first time, AC threshold voltage (Vth) of 1S1R OTS-PCM was studied, which will impact the operation scheme. To achieve Tera bits per chip density, six layers 1Znm 3D XPCM with OTS showing high Vth and low leakage current, and scalable periphery circuit are required.
Purpose: Family caregivers provide essential support as stroke survivors' return to community living, but it is not standard clinical practice to prepare or provide ongoing support for their ...care-giving role. In addition, health care professionals (HCPs) experiences with providing support to caregivers have not been explored previously. The objectives of this qualitative study were to: (1) explore the support needs over time from the perspective of caregivers, (2) explore the support needs over time from the perspective of HCPs, and (3) compare and contrast caregivers' and HCPs' perspectives. Methods: A qualitative study with stroke family caregivers (n = 24) and HCPs (n = 14). In-depth interviews were audio taped, transcribed, and analyzed using Framework Analysis. Results: Three main themes emerged concerning: (1) types and intensity of support needed; (2) who provides support and the method of providing support; and (3) primary focus of care. These themes are discussed in relation to the TIR framework. Conclusions: Caregivers' needs for support and the individuals most suited to providing support change across the stroke survivor's recovery trajectory. Changes to service delivery to better support caregivers may include: (1) addressing caregivers' changing needs across the care continuum; (2) implementing a family-centered model of care; and (3) providing 7-day per week inpatient rehabilitation.
Implications for Rehabilitation
Caregivers support needs change across the care continuum
Support programs should be offered outside usual working hours
Health care professionals should address the needs of the stroke survivor and their family caregiver
Caregivers benefit from receiving support from health care professionals, family, friends, and care-giving peers
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