Silicon photonics devices for integrated analog signal processing and sampling

Silicon photonics offers the possibility of a reduction in size weight and power for many optical systems, and could open up the ability to build optical systems with complexities that would otherwise be impossible to achieve. Silicon photonics is an emerging technology that has already been inserted into commercial communication products. This technology has also been applied to analog signal processing applications. MIT Lincoln Laboratory in collaboration with groups at MIT has developed a toolkit of silicon photonic devices with a focus on the needs of analog systems. This toolkit includes low-loss waveguides, a high-speed modulator, ring resonator based filter bank, and all-silicon photodiodes. The components are integrated together for a hybrid photonic and electronic analog-to-digital converter. The development and performance of these devices will be discussed. Additionally, the linear performance of these devices, which is important for analog systems, is also investigated

On the Optimality of Vagueness: "Around", "Between", and the Gricean Maxims

Why is our language vague? We argue that in contexts in which a cooperative speaker is not perfectly informed about the world, the use of vague expressions can offer an optimal tradeoff between truthfulness (Gricean Quality) and informativeness (Gricean Quantity). Focusing on expressions of approximation such as "around", which are semantically vague, we show that they allow the speaker to convey indirect probabilistic information, in a way that gives the listener a more accurate representation of the information available to the speaker than any more precise expression would (intervals of the form "between"). We give a probabilistic treatment of the interpretation of "around", and offer a model for the interpretation and use of "around"-statements within the Rational Speech Act (RSA) framework. Our model differs in substantive ways from the Lexical Uncertainty model often used within the RSA framework for vague predicates

Decreasing initial telomere length in humans intergenerationally understates age-associated telomere shortening

Telomere length shortens with aging, and short telomeres have been linked to a wide variety of pathologies. Previous studies suggested a discrepancy in age-associated telomere shortening rate estimated by cross-sectional studies versus the rate measured in longitudinal studies, indicating a potential bias in cross-sectional estimates. Intergenerational changes in initial telomere length, such as that predicted by the previously described effect of a father's age at birth of his offspring (FAB), could explain the discrepancy in shortening rate measurements. We evaluated whether changes occur in initial telomere length over multiple generations in three large datasets and identified paternal birth year (PBY) as a variable that reconciles the difference between longitudinal and cross-sectional measurements. We also clarify the association between FAB and offspring telomere length, demonstrating that this effect is substantially larger than reported in the past. These results indicate the presence of a downward secular trend in telomere length at birth over generational time with potential public health implications

Some remarks on L¹ embeddings in the subelliptic setting

In this paper we establish an optimal Lorentz estimate for the Riesz potential inthe L¹ regime in the setting of a stratified group G: Let Q ≥ 2 be the homogeneous dimension of G and [Formula: see text] denote the Riesz potential of order α on G. Then, for every α∈(0,Q), there exists a constant C = C(α,Q) > 0 such that [Formula: see text]for all [Formula: see text] such that [Formula: see text], where X denotes the horizontal gradient

Individual cognitive stimulation therapy for dementia : a clinical effectiveness and cost-effectiveness pragmatic, multicentre, randomised controlled trial

Background Group cognitive stimulation therapy programmes can benefit cognition and quality of life for people with dementia. Evidence for home-based, carer-led cognitive stimulation interventions is limited. Objectives To evaluate the clinical effectiveness and cost-effectiveness of carer-delivered individual cognitive stimulation therapy (iCST) for people with dementia and their family carers, compared with treatment as usual (TAU). Design A multicentre, single-blind, randomised controlled trial assessing clinical effectiveness and cost-effectiveness. Assessments were at baseline, 13 weeks and 26 weeks (primary end point). Setting Participants were recruited through Memory Clinics and Community Mental Health Teams for older people. Participants A total of 356 caregiving dyads were recruited and 273 completed the trial. Intervention iCST consisted of structured cognitive stimulation sessions for people with dementia, completed up to three times weekly over 25 weeks. Family carers were supported to deliver the sessions at home. Main outcome measures Primary outcomes for the person with dementia were cognition and quality of life. Secondary outcomes included behavioural and psychological symptoms, activities of daily living, depressive symptoms and relationship quality. The primary outcome for the family carers was mental/physical health (Short Form questionnaire-12 items). Health-related quality of life (European Quality of Life-5 Dimensions), mood symptoms, resilience and relationship quality comprised the secondary outcomes. Costs were estimated from health and social care and societal perspectives. Results There were no differences in any of the primary outcomes for people with dementia between intervention and TAU [cognition: mean difference –0.55, 95% confidence interval (CI) –2.00 to 0.90; p-value = 0.45; self-reported quality of life: mean difference –0.02, 95% CI –1.22 to 0.82; p-value = 0.97 at the 6-month follow-up]. iCST did not improve mental/physical health for carers. People with dementia in the iCST group experienced better relationship quality with their carer, but there was no evidence that iCST improved their activities of daily living, depression or behavioural and psychological symptoms. iCST seemed to improve health-related quality of life for carers but did not benefit carers’ resilience or their relationship quality with their relative. Carers conducting more sessions had fewer depressive symptoms. Qualitative data suggested that people with dementia and their carers experienced better communication owing to iCST. Adjusted mean costs were not significantly different between the groups. From the societal perspective, both health gains and cost savings were observed. Conclusions iCST did not improve cognition or quality of life for people with dementia, or carers’ physical and mental health. Costs of the intervention were offset by some reductions in social care and other services. Although there was some evidence of improvement in terms of the caregiving relationship and carers’ health-related quality of life, iCST does not appear to deliver clinical benefits for cognition and quality of life for people with dementia. Most people received fewer than the recommended number of iCST sessions. Further research is needed to ascertain the clinical effectiveness of carer-led cognitive stimulation interventions for people with dementia

Driven dynamics and rotary echo of a qubit tunably coupled to a harmonic oscillator

We have investigated the driven dynamics of a superconducting flux qubit that is tunably coupled to a microwave resonator. We find that the qubit experiences an oscillating field mediated by off-resonant driving of the resonator, leading to strong modifications of the qubit Rabi frequency. This opens an additional noise channel, and we find that low-frequency noise in the coupling parameter causes a reduction of the coherence time during driven evolution. The noise can be mitigated with the rotary-echo pulse sequence, which, for driven systems, is analogous to the Hahn-echo sequence

Older adults’ experience of neuropsychological assessments for dementia screening in South India: a qualitative study

Background: In community settings, neuropsychological assessment is the most commonly employed method for early recognition of dementia. However, little is known about the experience and perspectives of older adults when they undertake neuro psychological assessments in low-and middle-income countries (LMICs), including India. Methods: We conducted semi-structured interviews for 11 individuals (aged between 64 and 88 years) who had undergone cognitive assessment in the CST International (Cognitive Stimulation Therapy International) study and were free from dementia. The transcripts were analysed manually utilising Interpretative Phenomenological Analysis to develop key themes. Results: When data were analysed three super-ordinate themes (experiences related to the process, content and outcomes) each with a set of subordinate themes emerged. Conclusions: This study highlights the need for a thorough planning of pre-assessment briefing for equipping participants with adequate information related to the neuro psychological assessment: its indication, length of procedure, contents of the test, possible outcomes, medical implications of those outcomes, possible therapeutic options if diagnosed with lower cognitive function.We discuss our findings in relation to extant knowledge and explore issues clinicians should consider when conducting neuro psychological assessments in LMIC settings

Cancer stem cells: Mediators of tumorigenesis and metastasis in head and neck squamous cell carcinoma

BackgroundCancer stem cells (CSCs) represent a subpopulation of cells responsible for tumor growth. Their role in head and neck squamous cell carcinoma (HNSCC) tumorigenesis and metastasis remains uncertain.MethodsWound healing and an orthotopic animal model were used to study cells expressing the CSC phenotype (CD44high and aldehyde dehydrogenase [ALDH]+) and assess mobility, tumorigenesis, and metastasis. A prospective collection of 40 patient‐derived primary HNSCC specimens were analyzed for CSC‐proportion compared to clinical variables.ResultsCSCs exhibited significantly faster wound closure and greater tumorigenesis and regional metastasis in vivo than non‐CSCs. In primary patient tumors, size and advanced stage were correlated with elevated proportion of CSCs, however, not with survival.ConclusionHNSCC stem cells mediate tumorigenesis and regional metastasis in vivo. In primary patient tumors, CSC‐proportion was associated with tumor size and stage, but not with metastatic spread or survival. CSC burden alone may only represent a minor variable in understanding CSCs and metastasis. © 2014 Wiley Periodicals, Inc. Head Neck 37: 317–326, 2015Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110728/1/hed23600.pd

Predictors of survival after total laryngectomy for recurrent/persistent laryngeal squamous cell carcinoma

BackgroundTotal laryngectomy remains the treatment of choice for recurrent/persistent laryngeal squamous cell carcinoma (SCC) after radiotherapy (RT) or chemoradiotherapy (CRT). However, despite attempts at aggressive surgical salvage, survival in this cohort remains suboptimal.MethodsA prospectively maintained single‐institution database was queried for patients undergoing total laryngectomy for recurrent/persistent laryngeal SCC after initial RT/CRT between 1998 and 2015(n = 244). Demographic, clinical, and survival data were abstracted. The Kaplan‐Meier survival curves and hazard ratios (HRs) were calculated.ResultsFive‐year overall survival (OS) was 49%. Five‐year disease‐free survival (DFS) was 58%. Independent predictors of OS included severe comorbidity (Adult Comorbidity Evaluation‐27 [ACE‐27] scale; HR 3.76; 95% confidence interval [CI] 1.56‐9.06), and positive recurrent clinical nodes (HR 2.91; 95% CI 1.74‐4.88).ConclusionSevere comorbidity status is the strongest predictor of OS, suggesting that increased attention to mitigating competing risks to health is critical. These data may inform a risk prediction model to allow for focused shared decision making, preoperative health optimization, and patient selection for adjuvant therapies.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139972/1/hed24918.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139972/2/hed24918_am.pd