| 1. |
- Dochev, Dimitar Milkov, 1981, et al.
(författare)
-
A Technology Demonstrator for 1.6–2.0 THz Waveguide HEB Receiver with a Novel Mixer Layout
- 2011
-
Ingår i: Journal of Infrared, Millimeter, and Terahertz Waves. - : Springer Science and Business Media LLC. - 1866-6892 .- 1866-6906. ; 32:4, s. 451-465
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present our studies on a technology demonstrator for a balanced waveguide hot-electron bolometer (HEB) mixer operating in the 1.6–2.0 THz band. The design employs a novel layout for the HEB mixer combining several key technologies: all-metal THz waveguide micromachining, ultra-thin NbN film deposition and a micromachining of a silicon-on-insulator (SOI) substrate to manufacture the HEB mixer. In this paper, we present a novel mixer layout that greatly facilitates handling and mounting of the mixer chip via self-aligning as well as provides easy electrical interfacing. In our opinion, this opens up a real prospective for building multi-pixel waveguide THz receivers. Such receivers could be of interest for SOFIA, possible follow up of the Herschel HIFI, and even for ground based telescopes yet over limited periods of time with extremely dry weather (PWV less than 0.1 mm).
|
|
| 2. |
- Furtula, Vedran, 1981, et al.
(författare)
-
Waveguide Bandpass Filters for Millimeter-Wave Radiometers
- 2013
-
Ingår i: Journal of Infrared, Millimeter, and Terahertz Waves. - : Springer Science and Business Media LLC. - 1866-6892 .- 1866-6906. ; 34:12, s. 824-836
-
Tidskriftsartikel (refereegranskat)abstract
- A fundamental requirement for most mm-wave heterodyne receivers is the rejection of the input image signal which is located close to the local oscillator frequency. For this purpose we use a bandpass filter, which for heterodyne receivers is also called an image rejection filter. In this paper we present a systematic approach to the design of a waveguide bandpass filter with a passband from 100 to 110 GHz and upper rejection bandwidth in the range from 113 to 145 GHz. We consider two non-tunable filter configurations: the first one is relatively selective with 11 sections (poles) whereas the second one is simpler with 5 sections. We used established design equations to propose an initial guess for the geometries of the filters, optimized the geometries, constructed the filters using two different milling methods, measured their transmission and reflection characteristics, and compared the measurements with numerical simulations. Measurements of both filters agree well with simulations in frequency response and rejection bandwidth. The insertion loss of the 11-pole filter is better than 10 dB and that of the 5-pole filter is better than 5 dB. The 11-pole filter has a sharper attenuation roll-off compared with the 5-pole filter. The upper out-of-band rejection is better than 40 dB up to 145 GHz for the 11-pole filter and up to 155 GHz for the 5-pole filter.
|
|
| 3. |
- Johansson, Jessica, 1977-, et al.
(författare)
-
Decreased binding capacity (Bmax) of muscarinic acetylcholine receptors in fibroblasts from boys with attention-deficit/hyperactivity disorder (ADHD)
- 2013
-
Ingår i: ADHD Attention Deficit and Hyperactivity Disorders. - Berlin, Germany : Springer Berlin/Heidelberg. - 1866-6116 .- 1866-6647. ; 5:3, s. 267-271
-
Tidskriftsartikel (refereegranskat)abstract
- Monoaminergic dysregulation is implicated in attention-deficit/hyperactivity disorder (ADHD), and methylphenidate and amphetamines are the most frequently prescribed pharmacological agents for treating ADHD. However, it has recently been proposed that the core symptoms of the disorder might be due to an imbalance between monoaminergic and cholinergic systems. In this study, we used fibroblast cell homogenates from boys with and without ADHD as an extraneural cell model to examine the cholinergic receptor density, that is, muscarinic acetylcholine receptors (mAChRs). We found that the binding capacity (Bmax) of [³H] Quinuclidinyl benzilate (³H-QNB) to mAChRs was decreased by almost 50 % in the children with ADHD (mean = 30.6 fmol/mg protein, SD = 25.6) in comparison with controls [mean = 63.1 fmol/mg protein, SD = 20.5, p ≤ 0.01 (Student's unpaired t test)]. The decreased Bmax indicates a reduced cholinergic receptor density, which might constitute a biomarker for ADHD. However, these preliminary findings need to be replicated in larger ADHD and comparison cohorts
|
|
| 4. |
- Johnson, Mats, 1956, et al.
(författare)
-
Fatty acids in ADHD: plasma profiles in a placebo-controlled study of Omega 3/6 fatty acids in children and adolescents.
- 2012
-
Ingår i: Attention Deficit and Hyperactivity Disorders. - : Springer Science and Business Media LLC. - 1866-6116 .- 1866-6647. ; 4:4, s. 199-204
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess baseline levels and changes in plasma fatty acid profiles in children and adolescents with ADHD, in a placebo-controlled study with Omega 3/6 supplementation, and to compare with treatment response. Seventy-five children and adolescents aged 8-18years with DSM-IV ADHD were randomized to 3months of Omega 3/6 (Equazen eye q) or placebo, followed by 3months of open phase Omega 3/6 for all. n-3, n-6, n-6/n-3 ratio, EPA and DHA in plasma were measured at baseline, 3 and 6months. Subjects with more than 25% reduction in ADHD symptoms were classified as responders. At baseline, no significant differences in mean fatty acid levels were seen across active/placebo groups or responder/non-responder groups. The 0-3month changes in all parameters were significantly greater in the active group (p<0.01). Compared to non-responders, the 6-month responders had significantly greater n-3 increase at 3months and decrease in n-6/n-3 ratio at 3 and 6months (p<0.05). Omega 3/6 supplementation had a clear impact on fatty acid composition of plasma phosphatidyl choline in active versus placebo group, and the fatty acid changes appear to be associated with treatment response. The most pronounced and long-lasting changes for treatment responders compared to non-responders were in the n-6/n-3 ratio.
|
|
| 5. |
- Gustafsson, Peik, et al.
(författare)
-
Motor function and perception in children with neuropsychiatric and conduct problems : results from a population based twin study
- 2014
-
Ingår i: Journal of Neurodevelopmental Disorders. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 1866-1947 .- 1866-1955.
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Children with early symptomatic psychiatric disorders such as Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) have been found to have high rates of motor and/or perception difficulties. However, there have been few large-scale studies reporting on the association between Conduct Disorder (CD) and motor/perception functions. The aim of the present study was to investigate how motor function and perception relate to measures of ADHD, ASD, and CD. METHODS: Parents of 16,994 Swedish twins (ages nine and twelve years) were interviewed using the Autism-Tics, ADHD and other Comorbidities inventory (A-TAC), which has been validated as a screening instrument for early onset child psychiatric disorders and symptoms. Associations between categorical variables of scoring above previously validated cut-off values for diagnosing ADHD, ASD, and CD on the one hand and motor and/or perception problems on the other hand were analysed using cross-tabulations, and the Fisher exact test. Associations between the continuous scores for ADHD, ASD, CD, and the subdomains Concentration/Attention, Impulsiveness/Activity, Flexibility, Social Interaction and Language, and the categorical factors age and gender, on the one hand, and the dependent dichotomic variables Motor control and Perception problems, on the other hand, were analysed using binary logistic regression in general estimated equation models. RESULTS: Male gender was associated with increased risk of Motor control and/or Perception problems. Children scoring above the cut-off for ADHD, ASD, and/or CD, but not those who were 'CD positive' but 'ADHD/ASD negative', had more Motor control and/or Perception problems, compared with children who were screen-negative for all three diagnoses. In the multivariable model, CD and Impulsiveness/Activity had no positive associations with Motor control and/or Perception problems. CONCLUSIONS: CD symptoms or problems with Impulsiveness/Activity were associated with Motor control or Perception problems only in the presence of ASD symptoms and/or symptoms of inattention. Our results indicate that children with CD but without ASD or inattention do not show a deviant development of motor and perceptual functions. Therefore, all children with CD should be examined concerning motor control and perception. If problems are present, a suspicion of ADHD and/or ASD should be raised.
|
|
| 6. |
- Falck-Ytter, Terje, et al.
(författare)
-
Eye tracking in early autism research
- 2013
-
Ingår i: Journal of Neurodevelopmental Disorders. - : Springer Science and Business Media LLC. - 1866-1955 .- 1866-1947. ; 5, s. 28-
-
Forskningsöversikt (refereegranskat)abstract
- Eye tracking has the potential to characterize autism at a unique intermediate level, with links 'down' to underlying neurocognitive networks, as well as 'up' to everyday function and dysfunction. Because it is non-invasive and does not require advanced motor responses or language, eye tracking is particularly important for the study of young children and infants. In this article, we review eye tracking studies of young children with autism spectrum disorder (ASD) and children at risk for ASD. Reduced looking time at people and faces, as well as problems with disengagement of attention, appear to be among the earliest signs of ASD, emerging during the first year of life. In toddlers with ASD, altered looking patterns across facial parts such as the eyes and mouth have been found, together with limited orienting to biological motion. We provide a detailed discussion of these and other key findings and highlight methodological opportunities and challenges for eye tracking research of young children with ASD. We conclude that eye tracking can reveal important features of the complex picture of autism.
|
|
| 7. |
|
|
