Word Mode: a crowding-free reading protocol for individuals with macular disease

Central retinal loss through macular disease markedly reduces the ability to read largely because identification of a word using peripheral vision is negatively influenced by nearby text, a phenomenon termed visual crowding. Here, we present a novel peripheral reading protocol, termed Word Mode, that eliminates crowding by presenting each word in isolation but in a position that mimics its natural position in the line of text being read, with each new word elicited using a self-paced button press. We used a gaze-contingent paradigm to simulate a central scotoma in four normally-sighted observers, and measured oral reading speed for text positioned 7.5° in the inferior field. Compared with reading whole sentences, our crowding-free protocol increased peripheral reading speeds by up to a factor of seven, resulted in significantly fewer reading errors and fixations per sentence, and reduced both the critical print size and the text size required for spot reading by 0.2–0.3 logMAR. We conclude that the level of reading efficiency afforded by the crowding-free reading protocol Word Mode may return reading as a viable activity to many individuals with macular disease

Collapse of a Magnetized Star to a Black Hole

We study of the collapse of a magnetized spherical star to a black hole in general relativity theory. The matter and gravitational fields are described by the exact Oppenheimer-Snyder solution for the collapse of a spherical, homogeneous dust ball. We adopt a ``dynamical Cowling approximation'' whereby the matter and the geometry (metric), while highly dynamical, are unaffected by the electromagnetic fields. The matter is assumed to be perfectly conducting and threaded by a dipole magnetic field at the onset of collapse. We determine the subsequent evolution of the magnetic and electric fields without approximation; the fields are determined analytically in the matter interior and numerically in the vacuum exterior. We apply junction conditions to match the electromagnetic fields across the stellar surface. We use this model to experiment with several coordinate gauge choices for handling spacetime evolution characterized by the formation of a black hole and the associated appearance of singularities. These choices range from ``singularity avoiding'' time coordinates to ``horizon penetrating'' time coordinates accompanied by black hole excision. The later choice enables us to integrate the electromagnetic fields arbitrarily far into the future. At late times the longitudinal magnetic field in the exterior has been transformed into a transverse electromagnetic wave; part of the electromagnetic radiation is captured by the hole and the rest propagates outward to large distances. The solution we present for our simple scenario can be used to test codes designed to treat more general evolutions of relativistic MHD fluids flowing in strong gravitational fields in dynamical spacetimes.Comment: 22 pages, 12 figures; scheduled for March 10 issue of Ap

The ultrafast ground and excited state dynamics of cis-hexatriene in cyclohexane

One- and two-color kinetics have been combined with broadband ultraviolet transient absorption spectroscopy in the 265–300 nm region to elucidate the photophysics of cis-hexatriene in cyclohexane solvent. The lowest singlet excited state, the 2 1A121A1 state, is observed to have a lifetime of 200±50 fs. The ground-state hexatriene is produced vibrationally hot. The excess vibrational energy permits ultrafast isomerization around the C–C single bonds in hexatriene. This results in a dynamic equilibrium of the three cis-hexatriene rotamers, which then relaxes multiexponentially to the room-temperature distribution in which the di-s-trans-Z-hexatriene form predominates. The peak of the mono-s-trans (cZt-HT) population is estimated to be ∼50%. Vibrational cooling results in trapping of a small amount, ∼8%, of cZt-HT that relaxes on a much longer time scale as the barrier to isomerization becomes important. An estimate of the absorption spectrum of cZt-HT is deduced from analysis of the spectral data at 50 ps. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70051/2/JCPSA6-107-13-4985-1.pd

The ultrafast photochemical ring-opening reaction of 1,3-cyclohexadiene in cyclohexane

The ring-opening reaction of 1,3-cyclohexadiene in cyclohexane solution and the subsequent photoproduct cooling dynamics have been investigated by using two-color transient absorption kinetic measurements and novel time-resolved absorption spectroscopy in the 260–300 nm spectral region. The initial photoproduct in this reaction, s-cis,Z,s-cis-1,3,5-hexatrienes-cis,Z,s-cis-1,3,5-hexatriene (cZc-HT) is formed on a ∼ 250 fs∼250fs time scale. Spectra deduced for time delays very close to zero, as well as calculated Rice–Ramsperger–Kassel–Marcus unimolecular reaction rates, provide strong evidence that the quantum yield for the reaction is determined before any relaxation occurs on the ground state. Upon formation, the vibrationally excited hexatriene photoproduct is able to isomerize around C–C single bonds freely. As a result, the evolution observed in the transient absorption measurements represents a combination of rotamer population dynamics and thermalization due to energy transfer to the solvent. Three distinct time scales for relaxation are observed. These time scales correspond approximately to the development of an evolving equilibrium of Z-HT rotamers (1–5 ps), vibrational cooling and thermal equilibration with the surroundings (10–20 ps), and activated isomerization of trapped cZt-HT to tZt-HT (≫100 ps).(≫100ps). © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70793/2/JCPSA6-108-2-556-1.pd

Memory Tracks: song-task association in dementia care, a preliminary study

A multi-shareholder investigation into the effects of music to aid the day to day care of people living with dementia. Music builds long-term associative memories, often closely tied to emotions which can be more resilient to loss than other types of memory. Memory Tracks, a care platform can provides a personalised selection of music tailored to an individual dementia patient’s routine, their family and carers needs. The individualisation of music can also reduce the frequency of agitation in certain settings

Alzheimer disease genetic risk factor APOE e4, and cognitive abilities in 111,739 UK Biobank participants

Background: the apolipoprotein (APOE) e4 locus is a genetic risk factor for dementia. Carriers of the e4 allele may be more vulnerable to conditions that are independent risk factors for cognitive decline, such as cardiometabolic diseases. Objective: we tested whether any association with APOE e4 status on cognitive ability was larger in older ages or in those with cardiometabolic diseases. Subjects: UK Biobank includes over 500,000 middle- and older aged adults who have undergone detailed medical and cognitive phenotypic assessment. Around 150,000 currently have genetic data. We examined 111,739 participants with complete genetic and cognitive data. Methods: baseline cognitive data relating to information processing speed, memory and reasoning were used. We tested for interactions with age and with the presence versus absence of type 2 diabetes (T2D), coronary artery disease (CAD) and hypertension. Results: in several instances, APOE e4 dosage interacted with older age and disease presence to affect cognitive scores. When adjusted for potentially confounding variables, there was no APOE e4 effect on the outcome variables. Conclusions: future research in large independent cohorts should continue to investigate this important question, which has potential implications for aetiology related to dementia and cognitive impairment

Role of vasopressin in impaired water excretion in conscious rats with experimental cirrhosis

Role of vasopressin in impaired water excretion in conscious rats with experimental cirrhosis. The present study was undertaken to study the mechanism of impaired water excretion in experimental cirrhosis in the rat. Conscious rats in whom histologically proven cirrhosis was induced with carbon tetrachloride and phenobarbital were compared with control rats given phenobarbital alone. Impaired water excretion in experimental cirrhosis was verified by a basal hyponatremia (138 vs. 147 mEq/liter, P < 0.005) and an impaired excretion of water load (minimal urinary osmolality, 262 vs. 100 mOsm/kg; 58 vs. 102% of water load excreted, P < 0.001). To clarify the mechanism of this impaired water excretion, we measured glomerular filtration rate (GFR), renal blood flow (RBF), and vasopressin (VP) levels. In cirrhosis, GFR was normal but RBF was decreased (4.5 vs 6.8 ml/min/g, P < 0.01). VP levels were found to be higher in cirrhotic rats (1.61 vs. 0.71 pg/ml, P < 0.025). The significance of the impaired renal hemodynamics and the increase in VP was assessed by inducing cirrhosis in VP-free Brattle-boro (diabetes insipidus; DI) rats. Despite histologic, biochemical, and renal hemodynamic changes that were comparable to cirrhotic rats with an intact neurohypophysis, cirrhotic DI rats had no impairment in water excretion. To determine the cause of increased VP in experimental cirrhosis, we determined blood volume and systemic hemodynamics. Although plasma volume was greater in experimental cirrhosis (4.3 vs. 3.0 ml/100 g, P < 0.05), cirrhotic rats had a significantly lower peripheral resistance (0.37 vs. 0.42mm Hg/ml/min/kg, P < 0.05) and mean arterial pressure (104 vs. 120mm Hg, P < 0.001) than did control rats. These results document that experimental cirrhosis in the rat is associated with impaired renal water excretion in association with both abnormal renal hemodynamics and increased VP levels. The impaired water excretion, however, is solely VP mediated. The nonosmolar stimulus for VP release may be due to abnormal systemic hemodynamics.Rôle de la vasopressine dans l'altération de l'excrétion de l'eau par le rat conscient atteint de cirrhose expérimentale. Cette étude a été entreprise pour élucider le mécanisme de l'altération de l'excrétion de l'eau au cours de la cirrhose du rat. Des rats conscients chez lesquels une cirrhose prouvée histologiquement a été induite par le tétrachlorure et le phénobarbital ont été comparés à des rats contrôles recevant seulement le phénobarbital. L'altération de l'excrétion de l'eau dans la cirrhose expérimentale a été vérifiée par l'hyponatrémie basale (138 vs. 147 mEq/litre, P < 0,005) et le défaut d'excrétion d'une charge en eau (osmolalité urinaire minimale 262 vs. 100 mOsm/kg; 58 vs. 102% de la charge d'eau sont excrétés, P < 0,001). Pour élucider le mécanisme de cette altération de l'excrétion de l'eau le débit de filtration glomérulaire (GFR), le débit sanguin rénal (RBF) et les concentrations de vasopressine (VP) ont été mesurés. Dans la cirrhose GFR est normal alors que RBF est diminué (4,5 vs. 6,8 ml/min/gm, P < 0,01). VP est plus élevée chez les rats cirrhotiques (1,61 vs. 0,71 pg/ml, P < 0,025). La signification des modifications de l'hémodynamique rénale et de l'augmentation de VP a été évaluée en créant des cirrhoses chez des rats sans VP de la souche Brattleboro (DI). Malgré des modifications histologiques, biochimiques et hémodynamiques rénales qui sont comparables à celles des rats dont la neurohypophyse est intacte, les rats DI cirrhotiques n'ont pas d'altération de l'excrétion de l'eau. Pour connaître la cause de l'augmentation de VP dans la cirrhose expérimentale le volume sanguin et l'hémodynamique systémique ont été étudiés. Quoique le volume plasmatique soit augmenté dans la cirrhose expérimentale (4,3 vs. 3,0 ml/100 g, P < 0,05) les rats cirrhotiques ont des résistances périphériques inférieures (0,37 vs. 0,42mm Hg/ml/min/kg, P < 0,05) et une pression artérielle moyenne inférieure (104 vs. 120mm Hg, P < 0,001) à celles des rats contrôles. Ces résultats indiquent que la cirrhose expérimentale du rat comporte une altération de l'excrétion de l'eau associée à une hémodynamique rénale anormale et à des concentrations de VP augmentées. L'altération de l'excrétion de l'eau, cependant, a la vasopressione comme seul médiateur. Le stimulus non osmolaire de la libération de VP pourrait être l'anomalie de l'hémodynamique systémique

Assessing Wellbeing in People Living with Dementia Using Reminiscence Music with a Mobile App (Memory Tracks): A Mixed Methods Cohort Study

The number of people living with dementia is growing, leading to increasing pressure upon care providers. The mechanisms to reduce symptoms of dementia can take many forms and have the aim of improving the wellbeing and quality of life of the person living with dementia and those who care for them. Besides the person who has dementia, the condition has a profound impact upon their loved ones and carers. One therapeutic approach is the use of music, an area recognised as having potential benefit, but requiring further research. The present paper reports upon a mixed methods cohort study that examines the use of a musical mobile app as a way to promote song-task association in people living with dementia. The study took place in care home environments in the UK. A total of fourteen participants (N = 14) were recruited. Quantitative measurements were taken on a daily basis prior to, and during, use of the mobile app over several weeks. Metrics came from the complete Self-Assessment Manikin scale (arousal, valence, and dominance), and a subset of three from the Quality of Life in Alzheimer’s Disease questionnaire (physical health, memory, and life as a whole). Subsequently, semistructured interviews were conducted with staff at the care home to assess the impact of the app upon their role and the residents they care for. No significant differences were found in the combined quantitative measures for the ten (n = 10) sets of responses sufficient to be analysed. However, the qualitative results suggest that use of the mobile app produced positive changes in terms of behaviour, ability, and routine in the life of residents living with dementia. These findings contribute to the growing body of evidence-based research in the field of musical therapies for reducing symptoms of dementia and highlight elements where further study is warranted

Detection of OH absorption against PSR B1849+00

We have searched for OH absorption against seven pulsars using the Arecibo telescope. In both OH mainlines (at 1665 and 1667 MHz), deep and narrow absorption features were detected toward PSR B1849+00. In addition, we have detected several absorption and emission features against B33.6+0.1, a nearby supernova remnant (SNR). The most interesting result of this study is that a pencil-sharp absorption sample against the PSR differs greatly from the large-angle absorption sample observed against the SNR. If both the PSR and the SNR probe the same molecular cloud then this finding has important implications for absorption studies of the molecular medium, as it shows that the statistics of absorbing OH depends on the size of the background source. We also show that the OH absorption against the PSR most likely originates from a small (<30 arcsec) and dense (>10^5 cm^-3) molecular clump.Comment: 12 pages, 8 figures. Accepted for publication in Ap