Image compression quality measurement : a comparison of the performance of JPEG and fractal compression on satellite images

Thesis (MEng)--Stellenbosch University, 2000.ENGLISH ABSTRACT: The purpose of this thesis is to investigate the nature of digital image compression and the calculation of the quality of the compressed images. The work is focused on greyscale images in the domain of satellite images and aerial photographs. Two compression techniques are studied in detail namely the JPEG and fractal compression methods. Implementations of both these techniques are then applied to a set of test images. The rest of this thesis is dedicated to investigating the measurement of the loss of quality that was introduced by the compression. A general method for quality measurement (signal To Noise Ratio) is discussed as well as a technique that was presented in literature quite recently (Grey Block Distance). Hereafter, a new measure is presented. After this, a means of comparing the performance of these measures is presented. It was found that the new measure for image quality estimation performed marginally better than the SNR algorithm. Lastly, some possible improvements on this technique are mentioned and the validity of the method used for comparing the quality measures is discussed.AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om ondersoek in te stel na die aard van digitale beeldsamepersing en die berekening van beeldkwaliteit na samepersing. Daar word gekonsentreer op grysvlak beelde in die spesifieke domein van satellietbeelde en lugfotos. Twee spesifieke samepersingstegnieke word in diepte ondersoek naamlik die JPEG en fraktale samepersingsmetodes. Implementasies van beide hierdie tegnieke word op 'n stel toetsbeelde aangewend. Die res van hierdie tesis word dan gewy aan die ondersoek van die meting van die kwaliteitsverlies van hierdie saamgeperste beelde. Daar word gekyk na 'n metode wat in algemene gebruik in die praktyk is asook na 'n nuwer metode wat onlangs in die literatuur veskyn het. Hierna word 'n nuwe tegniek bekendgestel. Verder word daar 'n vergelyking van hierdie mates en 'n ondersoek na die interpretasie van die 'kwaliteit' van hierdie kwaliteitsmate gedoen. Daar is gevind dat die nuwe maatstaf vir kwaliteit net so goed en selfs beter werk as die algemene maat vir beeldkwaliteit naamlik die Sein tot Ruis Verhouding. Laastens word daar moontlike verbeterings op die maatstaf genoem en daar volg 'n bespreking oor die geldigheid van die metode wat gevolg is om die kwaliteit van die kwaliteitsmate te bepaa

Degree of fear of needles and preferred allergy immunotherapy treatment among children with allergic rhinitis: caregiver survey results

IntroductionA child's fear of needles may impact the preferred route of allergy immunotherapy (AIT) when choosing between subcutaneous immunotherapy (allergy shots) or sublingual immunotherapy (SLIT). A survey was conducted to understand caregiver health-seeking behavior for children with allergic rhinitis with or without conjunctivitis (AR/C) and explore if fear of needles impacted AIT decisions.MethodsCaregivers of children ages 5–17 years with AR/C were recruited from the Dynata US research panel to participate in an online survey from May-June 2023. The survey received institutional review board exemption status. SLIT-tablets were described as “under-the-tongue tablets”.ResultsAbout a third (34%) of surveyed caregivers (n = 437) reported their child had a severe fear of needles and 47% reported moderate fear. Of surveyed caregivers, 53% and 43% reported they had discussed allergy shots and SLIT-tablets, respectively, with their child's physician. SLIT-tablets were preferred by 84% of caregivers; 6% preferred injections and 10% had no preference. Caregivers of children with a severe fear of needles had the highest preference for SLIT-tablets (95%) vs. injections (2%); 85% and 60% of caregivers of children with moderate and low fear, respectively, preferred SLIT-tablets. Among caregivers of children with a severe fear of needles, a higher percentage agreed that their child would welcome taking SLIT-tablets than that their child would accept taking an ongoing series of allergy shots (93% vs. 43%, respectively).ConclusionsMost caregivers preferred SLIT-tablets over allergy shots for their child with AR/C. Preference for SLIT-tablets corresponded with the child's degree of fear of needles. Fear of needles should be included in AIT shared decision-making conversations

Skeletal Muscle-Specific Methyltransferase METTL21C Trimethylates p97 and Regulates Autophagy-Associated Protein Breakdown

Summary: Protein aggregates and cytoplasmic vacuolization are major hallmarks of multisystem proteinopathies (MSPs) that lead to muscle weakness. Here, we identify METTL21C as a skeletal muscle-specific lysine methyltransferase. Insertion of a β-galactosidase cassette into the Mettl21c mouse locus revealed that METTL21C is specifically expressed in MYH7-positive skeletal muscle fibers. Ablation of the Mettl21c gene reduced endurance capacity and led to age-dependent accumulation of autophagic vacuoles in skeletal muscle. Denervation-induced muscle atrophy highlighted further impairments of autophagy-related proteins, including LC3, p62, and cathepsins, in Mettl21c−/− muscles. In addition, we demonstrate that METTL21C interacts with the ATPase p97 (VCP), which is mutated in various human MSP conditions. We reveal that METTL21C trimethylates p97 on the Lys315 residue and found that loss of this modification reduced p97 hexamer formation and ATPase activity in vivo. We conclude that the methyltransferase METTL21C is an important modulator of protein degradation in skeletal muscle under both normal and enhanced protein breakdown conditions. : Wiederstein et al. describe the skeletal muscle methyltransferase Mettl21c. They found that ablation of Mettl21c in mice results in muscle weakness and disturbance of the protein degradation machinery. Those changes are hallmarks of multisystem proteinopathies. They demonstrate that Mettl21c modulates p97 activity, which is frequently mutated in human patients with muscle weakness. Keywords: methyltransferases, skeletal muscle, p97, atrophy, autophag