Optimising IIR Filters Using ARM NEON

ARMs processorserie Cortex-A9 har stöd för SIMD-instruktioner med hjälp av NEON MPE. Detta innebär att processorn kan använda sig av vektor-instruktioner som kan utföra operationer på ett flertal element med varje instruktion. Målet med bruk av NEON MPE är att öka prestandan, men då man försöker optimera en speciell IIR-filtertyp som kallas för "biquads" kan man stöta på problem. Problemen med NEON-optimering av "biquads" beror på att endast fem operationer krävs för varje iteration och att behandling av IIR-filter kräver att man behandlar en sampel i taget eftersom varje behandlat sampels värde beror på tidigare behandlade samplar. Rapporten ger en kort beskrivning och genomgång av hur IIR-filter och NEON-optimering fungerar. För att analysera NEON-optimering av biquad-filter skapas fyra olika implementationer av en audioeffekt. De fyra implementationerna jämför prestandan hos flyttalsaritmetik, fixpunkts-aritmetik och NEON-optimering samt en version som implementerar både fixpunktsaritmetik och NEON-optimering. Problemen med optimering av biquad-filter med hjälp av NEON-instruktioner löses genom parallell behandling av ljudkanalerna. Eftersom kanalerna är självständiga kan man fördubbla prestanda genom att utföra varje operation på såväl höger- som vänsterkanal. Vidare prestandaförbättring ges även då effektiviteten hos minnesoperationer förbättras och med hjälp av fixpunkts-behandling. Resultaten visar att fixpunktsversionen som använder sig av NEON-instruktioner är snabbast, men flyttalsversionen med NEON-instruktioner är bara marginellt långsammare och dessutom enklare att implementera. Användandet av NEON-instruktioner förbättrar prestandan med mellan 1,7-2,8 gånger i de fall som testas.The ARM Cortex-A9 CPU has a SIMD extension called NEON MPE. It allows for vector instructions that can perform operations on multiple elements in a single instruction. Whilst this usually improves performance, certain IIR filters called biquads pose problems as only five operations are necessary per sample and every iteration is dependent on the result of the previous result. A brief overview is given for IIR filters, the NEON extension and fixed-point processing. In order to analyse optimisation of biquad filters, an audio effect with four different implementations is produced, comparing results with/without fixed-point processing and with/without NEON optimisation. The problems introduced by the use of biquad filters are solved by running multiple channels in parallel. As the audio channels are independent, two samples can be calculated in parallel, which approximately doubles peformance. Further performance improvement is provided by improved memory operation efficiency and the use of fixed-point processing. The results show that the fixed-point NEON implementation is the fastest, however the floating-point NEON implementation is marginally slower but simpler to write. The use of NEON MPE improves performance by between 1.7 to 2.8 times in this case

Lower prostate cancer risk in Swedish men with the androgen receptor E213 A-allele

In a previous population-based study on 3369 European men with self-reported prostate cancer (PCa), it was shown that androgen receptor (AR) haplotype designated H2 was associated with high levels of serum PSA (prostate-specific antigen) concentration, and, at the same time, with low risk for PCa. The aim of this study was to replicate this finding in other cohorts, with registry-based cancer diagnosis. Using data from two population-based cohorts; the Malmo Diet and Cancer Study (MDCS, n = 12,121) and the Swedish Osteoporotic fractures in men study (MrOS, n = 1,120), 628 men with PCa and 1,374 controls were identified and genotyped. PCa data were collected from the Swedish national cancer registry. PCa odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for carriers of the particular AR haplotype, tagged by the rs6624304 T-allele. The 15% of men who were carriers of the AR haplotype H2 had approximately one-third lower risk for PCa diagnosis compared to those with the most common H1 variant (OR 0.65; 95% CI 0.45-0.94; p = 0.021). The same trend, although not statistically significant (OR 0.75; 95% CI 0.47-1.24; p = 0.275), was observed in MrOS Sweden. When both cohorts were merged, an even more significant result was observed (OR 0.68; 95% CI 0.51-0.90; p = 0.008). Swedish men with the variant AR haplotype H2, tagged by rs6624304, have significantly lower risk of PCa compared to those with the more common variant

High risk of hypogonadism in young male cancer survivors

Objective: Cancer and its treatment in childhood and young adulthood can cause hypogonadism, leading to increased risk of long-term morbidity and mortality. The aim of this study was to evaluate the risk of presenting with biochemical signs of hypogonadism in testicular cancer survivors (TCS) and male childhood cancer survivors (CCS) in relation to the type of treatment given. Design: Case-control study. Patients: Ninety-two TCS, 125 CCS (mean age 40 and median age 34 years, respectively; mean follow-up time 9.2 and 24 years, respectively) and a corresponding number of age-matched controls. Measurements: Fasting morning blood samples were analysed for total testosterone (TT), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The odds ratios (OR) for hypogonadism, defined as primary, secondary, compensated or ongoing androgen replacement, were calculated for TCS and CCS and for subgroups defined by diagnosis and treatment. Results: Hypogonadism was found in 26% of CCS and 36% of TCS, respectively (OR: 2.1, P = .025 and OR = 2.3, P = .021). Among CCS, the OR was further increased in those given testicular irradiation (OR = 28, P = .004). Radiotherapy other than cranial or testicular irradiation plus chemotherapy, or cranial irradiation without chemotherapy, associated also with increased ORs (OR = 3.7, P = .013, and OR = 4.4, P = .038, respectively). Among TCS, those receiving >4 cycles of cisplatin-based chemotherapy had OR = 17, P = .015. Conclusions: Biochemical signs of testosterone deficiency are recognized as markers of decreased life expectancy. Thus, the risk of hypogonadism in TCS and CCS should be recognized and emphasizes the need of long-term follow-up for these men

Androgen receptor polymorphism-dependent variation in prostate-specific antigen concentrations of European men

Background: Androgens acting via the androgen receptor (AR) stimulate production of PSA, which is a clinical marker of prostate cancer. Because genetic variants in the AR may have a significant impact on the risk of being diagnosed with prostate cancer, the aim was to investigate whether AR variants were associated with the risk of having PSA above clinically used cutoff thresholds of 3 or 4 ng/mL in men without prostate cancer.<p></p> Methods: Men without prostate cancer history (n = 1,744) were selected from the European Male Ageing Study cohort of 40 to 79-year-old men from eight different European centers. Using linear and logistic regression models, with age and center as covariates, we investigated whether AR variants (CAG repeat-length and/or SNP genotype) were associated with having serum PSA concentrations above 3 or 4 ng/mL, which often are set as cutoff concentrations for further investigation of prostate cancer.<p></p> Results: Carriers of the SNP rs1204038 A-allele (16% of the men) were more likely to have PSA>3 and 4 ng/mL (OR; 95% confidence intervals, 1.65; 1.13–2.40 and 1.87; 1.18–2.96, respectively) than G-allele carriers. They also had shorter CAG repeats (median 20 vs. 23, P < 0.0005), but CAG repeat length per se did not affect the PSA concentrations.<p></p> Conclusion: The A-allele of the SNP rs1204038 gives a 65% higher risk of having PSA above 3 ng/mL than the G-allele in men without prostate cancer, and thereby an increased risk of being referred for further examination on suspicion of prostate cancer.<p></p&gt