<p>Avsikten med examensarbetet har varit att undersöka möjligheter och förutsättningar för verkstadsföretaget HZ Rostfria AB, med verksamhet i Sandviken, att införskaffa utrustning för elektrolytpolering av rostfria detaljer.</p><p>För att kunna få en helhetsbild över hur elektrolytpoleringsbranschen ser ut i Sverige har de företag som öppet annonserar med att de arbetar med elektrolytpolering studerats. Företagen har studerats utifrån en rad kriterier, där den huvudsakliga inriktningen på verksamheten samt företagens läge geografiskt relativt Sandviken ansetts vara de viktigaste.</p><p>Utöver de företag som arbetar med elektrolytpolering har även olika tekniker för att åstadkomma elektrolytpolering studerats. Teknikerna har studerats med de produkter som idag tillverkas, samt som i framtiden skulle kunna komma att tillverkas av HZ Rostfria AB i åtanke.</p><p>I och med att elektrolytpolering klassas som en miljöfarlig verksamhet har även frågor rörande tillstånd för verksamheten studerats. Det primära har varit att studera processen som leder fram till att tillstånd för verksamheten erhålls, vilket per automatik också innefattat att studera vilka insatser som krävs av företaget.</p>

Recent research shows that human auditory steady-state responses (ASSRs) develop a resonance at 40 Hz and the dramatic amplitude increase of the Pb component of the middle latency response (MLR) accounts for the high amplitude of the ASSR at 40 Hz. The first part of this study aimed to investigate the ASSR resonance characteristics as a function of rate in guinea pigs. A study of the grand average of the peak-to-peak and fundamental frequency amplitudes does indeed show a resonance around 40 Hz in guinea pigs. Unlike human ASSRs, this resonance is very broad (26-52 Hz) and flat. The centrally recorded ASSRs are smaller and tend to have resonances at higher rates compared to temporal signals. The second part of the analysis investigated whether the superposition of transient responses can predict the acquired ASSRs at each corresponding rate. This superposition theory is one of two competing theories on the origin of the ASSRs, with the other centering on the induced phase synchronization of brain waves. In order to test the first theory, transient responses were used to create synthetic ASSRs, which were then compared to the acquired ASSRs via correlation coefficient and phasor analysis. For the 40 Hz ASSR, both temporal and central electrode synthesized ASSRs show a correlation coefficient above 0.80. In the comparison at 20 Hz, the correlation coefficient is very high (about 0.9) in the temporal electrode, yet significantly lower (about 0.7) for the central electrode. Furthermore, at 80 Hz, the correlation coefficient is significantly lower in both temporal and central electrodes (about 0.7). At all rates, the correlation coefficients are highest with low jitter sequences. Finally, phasor analysis was also used to test the superposition theory of the generation of the acquired ASSRs at 20, 40, and 80 Hz. Overall, in the temporal recordings at 40 Hz, the superposition of the MLR responses accurately predicted the acquired 40 Hz ASSR as demonstrated by both magnitude and phase analysis. The recordings made in the central electrode only predicted the acquired ASSR in its phases, with significant differences found in magnitude at its main harmonics. Similarly, at 20 and 80 Hz in both temporal and central electrodes, the synthetic ASSRs did not appear to fully predict the acquired ASSRs. Although the phases were successfully predicted, large magnitude variations were observed. As shown by mean prediction error plots, the acquired ASSRs are best predicted by low jitter sequences, followed by low-medium and medium jitter sequences.

Avsikten med examensarbetet har varit att undersöka möjligheter och förutsättningar för verkstadsföretaget HZ Rostfria AB, med verksamhet i Sandviken, att införskaffa utrustning för elektrolytpolering av rostfria detaljer. För att kunna få en helhetsbild över hur elektrolytpoleringsbranschen ser ut i Sverige har de företag som öppet annonserar med att de arbetar med elektrolytpolering studerats. Företagen har studerats utifrån en rad kriterier, där den huvudsakliga inriktningen på verksamheten samt företagens läge geografiskt relativt Sandviken ansetts vara de viktigaste. Utöver de företag som arbetar med elektrolytpolering har även olika tekniker för att åstadkomma elektrolytpolering studerats. Teknikerna har studerats med de produkter som idag tillverkas, samt som i framtiden skulle kunna komma att tillverkas av HZ Rostfria AB i åtanke. I och med att elektrolytpolering klassas som en miljöfarlig verksamhet har även frågor rörande tillstånd för verksamheten studerats. Det primära har varit att studera processen som leder fram till att tillstånd för verksamheten erhålls, vilket per automatik också innefattat att studera vilka insatser som krävs av företaget.

Cylindrical dielectric waveguides such as the optical fiber and photonic crystal fiber are very important passive devices in optical communication systems. There are many kinds of commercial software and methods of simulation at present. In this thesis, we proposed the following four methods to analyze arbitrarily profiled cylindrical dielectric waveguides: The first two methods are modified from published work while the last two methods are entirely developed by ourselves. 1. Cylindrical ABCD matrix method: We take the four continuous electromagnetic field components as main variables and derive the exact four-by-four matrix (with Bessel functions) to relate the four field vector within each homogeneous layer. The electromagnetic field components of the inner and outer layer can propagate toward one of the selected interface of our choice by using the method of ABCD matrix. We can then solve for the £]-value of the waveguide mode with this nonlinear inhomogeneous matrix equation. 2. Runge-Kutta method: Runge-Kutta method is mostly used to solve the initial value problems of the differential equations. In this thesis, we introduce the Runge-Kutta method to solve the first-order four-by-four nonlinear differential equation of the electromagnetic field components and find the £]-value of the cylindrical dielectric waveguides in a similar way depicted in method one. 3. Coupled Ez and Hz method: It uses the axial electromagnetic filed components to solve cylindrical dielectric waveguides. The formulation is similar to cylindrical ABCD matrix method, but it requires less variables then cylindrical ABCD matrix method. The numerical solution obtained from this method is most stable, but it is more complicated to derive harder to write the program. 4. Simple basis expansion method: The simple trigonometric functions (sine or cosine) are chosen as the bases of the horizontal coupled magnetic field equation derived from the second-order differential equation of the transverse magnetic field components. We do not select the horizontal coupling electric field because the normal component of the electric field is discontinuous on the interface. But the normal and tangential components of the magnetic field are continuous across the interfaces. The modal solution problem is converted to a linear matrix eigenvalue-eigenvector equation which is solved by the standard linear algebra routines. We will compare these four numerical methods with one another. The characteristics and advantage as well as the disadvantage of each method will be studied and compared in detail.

The purpose of this study was to explore the ways tuning to A = 432 Hz affects emotional response, timbre, sound quality, character and tone compared to the standard tuning of A = 440 Hz, and whether or not it is humanly possible to discern a difference between these two. This was all done in an effort to evaluate claims that A = 432 Hz is superior to standard tuning in regards the previously mentioned factors. For this to be done, the history and development of tuning standards as well as intonation systems, presented alongside theories on the basic physics of sound, the effect of spectral manipulation on timbre and sound, and finally memory structures for remembering musical pitches. As a musician and composer, exploring new ways of creating emotion and controlling the effects of a composition, and dispelling potential misinformation is always a worthwhile pursuit. The study was performed by way of surveys where respondents were asked to listen to a composition in two versions, one in A = 440 Hz and the other in A = 432 Hz and then rate the perceived similarity between these two. They were then asked to give their answer regarding preference and associations of character and emotional response to each version. Results show that the claims of the A = 432 Hz proponents might not be as simple as portrayed, but rather a more complex series of relationships. There is support for the idea that the two tunings are unique enough for the average human to discern a difference between the two, and that some type of unique character is contained in each tuning.

Oscillations in the brain’s electrical potential, recorded through the technique of electroencephalography (EEG), reflect the ensemble activity of a large population of neurons. Auditory steady-state response (ASSR) is the time-locked entrainment in EEG to an auditory stimulus such as a train of clicks. ASSR to a 40 Hz (gamma frequency) click train is especially reduced in schizophrenia patients, reflecting the sensory processing deficits that impact real-world functional outcomes. Since the 40 Hz ASSR is demonstrable across species and is responsive to pharmacological treatments, it can be a translational biomarker for drug development studies. Prototypical antipsychotic drugs (APDs) like haloperidol and clozapine are examples of typical and atypical classes used to treat schizophrenia patients. While both are D2 receptor blockers, they have additional pharmacological effects that may differentiate them. Here, we investigated the acute effect of clozapine (atypical) or haloperidol (typical) on the 40 Hz ASSR, in two independent studies. The doses for the two drugs were chosen to reflect comparable in vivo D2 receptor occupancy. We used female Sprague-Dawley rats implanted with epidural EEG recording electrodes. In the first experiment, vehicle or clozapine 2.5, 5, and 10 mg/kg were administered (sc) and the 40 Hz ASSR paradigm (65 dB, 40 clicks for 1 second, 2-sec inter-stimulus interval) was used to record responses at 30, 60, 90 and 120 minutes post-drug. Resting-state EEG was recorded at 60 minutes post-treatment. Treatment effects were evaluated on the evoked power and phase-locking factor (PLF), a measure of trial-to-trial consistency of the 40 Hz ASSR. Clozapine improved both measures in a dose and time-dependent manner. Clozapine also tended to reduce the resting-state gamma (30-100 Hz) power, a hallmark of cortical noise. However, the effect was not significant (P>0.05). Next, we tested the effect of haloperidol on the 40 Hz ASSR. Doses of 0.02 mg/kg -0.08 mg/kg (sc) were evaluated at 30, 60, 90 and 120-minutes post-injection. Haloperidol failed to improve the 40 Hz ASSR (evoked power and PLF). Moreover, it had no discernible effect on the resting-state gamma. These results show that despite the comparable blockade of D2 receptors, the putative target for these APDs, clozapine, and haloperidol have different effects on the 40 Hz ASSR. We conclude that the effects of clozapine on 40 Hz ASSR may be unrelated to its affinity to D2 receptors and may be mediated through other pharmacological mechanisms.

The 40 Hz auditory steady state response (ASSR) is an EEG response of local neural synchrony that is evoked by the repeated presentation of a 40 Hz click train. While the principal cortical generators of this response appear to be the bilateral primary auditory cortices as they show the largest phase locking and evoked power, other regions across the cortical mantle synchronize too, including the prefrontal cortex (PFC) that receives input from the primary auditory cortex and is involved in higher order cognitive functions. In schizophrenia, it is hypothesized that NMDA-mediated disruption in PFC function contributes to cognitive deficits including working memory and executive function. In rodents, NMDA antagonists reliably disrupt set shifting, a working memory task linked to PFC function. It is however not known if NMDA antagonism would disrupt the 40 Hz ASSR in PFC. In the following study, we equipped a group of female SD rats with epidural electrodes targeting the PFC (2.5 mm anterior and 0.8 mm lateral to bregma) and the primary auditory cortex (4.5 mm caudal, 7.5 mm lateral and 3.5 mm ventral to bregma). Two epidural screw electrodes on cerebellum served as ground and reference. After recovery from surgery and acclimation, rats were pretreated with small to modest doses of the NMDA antagonist MK801 (0.025, 0.05 and 0.1 mpk) or saline (1 ml/kg, sc) in a cross-over design, tethered to EEG cables and the EEG signal was amplified and acquired (Signal 7.0; CED1401 Micro 3). Trains of square waves (~ 1 ms duration; 40/s) were generated and played through the house speakers at ~ 65 dB SPL. EEG was acquired as 4 s sweeps while the click train played between 1-2 s of each sweep; 75 trials were recorded from each subject. Sixty minutes after vehicle treatment, robust EEG entrainment was noted in both the temporal cortex as well as the PFC. As expected, the EEG signal power from the temporal cortex was notably larger compared to the PFC. Nevertheless, both regions showed clear 40 Hz entrainment to click trains. However, MK801 effect on the 40 Hz ASSR was disparate across the two regions. In the prefrontal cortex, the intertrial coherence (ITC) of the 40 Hz ASSR was strongly disrupted by MK801 at all doses (P<0.001; Dunnett’s test). Evoked power was significantly reduced only at the highest dose (P<0.0001). In primary auditory cortex, relative to vehicle treatment, evoked power showed a significant increase after 0.025 mpk and 0.05 mpk dose but declined significantly after the 0.1 mpk dose (P<0.05). However, ITC was unaffected (P>0.05). These results indicate that gamma neural synchrony in the PFC is more vulnerable to NMDA antagonist- mediated disruption, as compared to the primary auditory cortex. Moreover, it suggests that executive and cognitive functions may be more readily compromised by NMDA-mediated transmission disturbance even as auditory processing is enhanced or unaffected.

No description available.

This essay summarizes my artistry and approach as it has evolved during my five years at the Royal Institute of Art in Stockholm. My artistry is multidisciplinary where I find inspiration in art, technology, science, and society. My artistic process often relates to a full concept, where I explore and tell multi-layered stories. I study and engage with scientific theories and engage with them in a playful and experimental non-scientific way. These stories are expressed in my work that are physical and digital created from my intent and from physical phenomena that the eye cannot always see.  I firstly describe how I have created paintings by using technology generated frequencies and how I have put them on canvas. “Painting with technology frequencies and vibrations” uses a technology-oriented approach in making paintings inspired from the Chladni plate method. The conclusion is that it was possible to capture frequencies on canvas.  Secondly, I describe how I have made paintings, and associated pieces, that relate to frequencies and disturbances in human characteristics. For the concept “Painting with emotional frequencies and vibrations” I brought in phenomena from quantum physics and specifically the observer effect to make the paintings. I focused on morals and ethics and how art possibly can positively affect us human beings. In my mind I also drew parallels to the future mass-surveillance society and how we may be affected by being observed all the time.

Tympanometry and acoustic stapedial reflex (ASR) are routinely used in audiology clinics to assess the functional integrity of the eardrum and middle ear system in humans. Conventional tympanometry (which delivers a probe tone of 226 Hz into the ear canal and measures the mobility of the eardrum as the air pressure in the ear canal is varied) and acoustic reflex testing are effective in detecting middle ear pathologies in children and adults. However, the clinical application of these two tests to infants younger than 7 months has major limitations. In recent years, high frequency tympanometry (HFT) with a probe tone of 1000 Hz has been trialled successfully in young infants (< 7 months) and research on ASRs as they apply to this age group is continuing. Although preliminary HFT data for this population are emerging, there has been no detailed study that describes the effect of age on HFT and ASR results, no clear guideline on ways to interpret the HFT results, and no investigation to measure the feasibility and reliability of the ASR findings. For these reasons, systematic investigation into the use of HFT and ASR measures for evaluating the middle ear function of young infants is warranted. This thesis aimed to: (i) investigate the feasibility of obtaining HFT and ASR findings from newborn and 6-week-old infants, and study the characteristics of the immittance findings in these two age groups; (ii) investigate methods within HFT to measure the middle ear admittance of newborn babies; (iii) establish normative HFT data from healthy newborn babies using the new component compensation method; (iv) examine the test-retest reliability of the ASR test in healthy neonates; and (v) investigate the test-retest reliability of the ASR test in 6-week-old infants. The aims of the thesis were met through five studies. In study one (Chapter 2), a pilot study was conducted to examine the feasibility of performing HFT and ASR in 42 healthy infants and study the characteristics of the immittance findings obtained from these infants using a longitudinal study design. In this pilot study, all infants were tested at birth and then re-tested approximately 6 weeks after the first test. This study confirmed the feasibility of obtaining valid immittance findings from healthy young infants. Most importantly, the findings of this pilot study revealed that the mean values of the majority of HFT parameters and acoustic stapedial reflex threshold (ASRT) obtained at 6 weeks were significantly greater than those obtained at birth, indicating the need to have separate sets of normative data for both tests for newborn and 6-week-old infants. In study 2 (Chapter 3), three different methods to measure middle ear admittance (often described as peak compensated static admittance) in 36 healthy neonates were compared. The three methods were the traditional baseline compensation method (compensated for the susceptance component at 200 daPa pressure) and two new component compensated methods (compensated for both the susceptance and conductance components at 200 daPa and -400 daPa). The results showed that the mean middle ear admittances obtained by compensating for the two components of admittance at a pressure of 200 daPa (YCC200) and -400 daPa (YCC-400) were significantly greater than that using the traditional baseline compensation method (YBC). The higher mean admittance results obtained using the new component compensated methods suggests that the two new methods have the potential to better separate normal from abnormal admittance results. The test-retest reliability of YBC, YCC200 and YCC-400 was investigated, with the result that a lower test-retest reliability was obtained for YCC-400 than for the other two measures. It was, therefore, concluded that the component compensation method compensated at 200 daPa may serve as an alternative method for estimating middle ear admittance, especially in the context of assessing neonates using HFT. In study 3 (Chapter 4), normative data were gathered using the new component compensation method (compensated at 200 daPa) on a group of 157 healthy newborn babies. In addition to the component compensated static admittance (YCC), normative data showing the 90 % ranges for tympanometric peak pressure, admittance at 200 daPa, uncompensated peak admittance, and traditional baseline compensated static admittance (YBC) were established in this study. No gender effect was found on any of the tympanometric measures. In study 4 (Chapter 5), the use of ASR to evaluate middle ear function in neonates was studied. The feasibility of obtaining ipsilateral ASR from neonates by stimulating their ears with a 2 kHz tone and broadband noise (BBN) was demonstrated. ASRs were elicited from 91.3% of 219 full-term normal neonates, while the remaining 8.7% of neonates who had flat tympanograms and no transient evoked otoacoustic emissions did not exhibit ASRs. Good test-retest reliability was demonstrated in the ASRT obtained using both the 2 kHz and BBN stimulus; there was no significant difference between test and retest conditions and intra-correlation coefficients of 0.83 for the 2 kHz tone and 0.76 for the BBN stimulus. In the last study (Chapter 6), the test-retest reliability of ASRT obtained from 70 6-week-old infants was investigated. The methodology described in Chapter 5 was followed. No significant difference in ASRT between test and retest conditions was found for the 2 kHz tone (mean ASRT = 67.3 dB HL versus 67.1 dB HL) and BBN stimulus (mean ASRT = 80.9 dB HL versus 81.6 dB HL). Good test-retest reliability of ASRT with intra-correlation coefficients of 0.78 was found for both the 2 kHz tone and the BBN stimulus. In essence, through achieving the aforementioned aims, the current research program was able to enhance the minimal literature available concerning the use of HFT and ASR testing in young infants. Ultimately, the findings presented in this thesis will inform clinicians of the recent developments in HFT and ASR testing, and assist them in evaluating the middle ear function of young infants with accuracy and confidence.