A systematic review and meta-analysis of artificial intelligence diagnostic accuracy in prostate cancer histology identification and grading

BACKGROUND

Artificial intelligence (AI) is a promising tool in pathology, including cancer diagnosis, subtyping, grading, and prognostic prediction.

METHODS

The aim of the study is to assess AI application in prostate cancer (PCa) histology. We carried out a systematic literature search in 3 databases. Primary outcome was AI accuracy in differentiating between PCa and benign hyperplasia. Secondary outcomes were AI accuracy in determining Gleason grade and agreement among AI and pathologists.

RESULTS

Our final sample consists of 24 studies conducted from 2007 to 2021. They aggregate data from roughly 8000 cases of prostate biopsy and 458 cases of radical prostatectomy (RP). Sensitivity for PCa diagnostic exceeded 90% and ranged from 87% to 100%, and specificity varied from 68% to 99%. Overall accuracy ranged from 83.7% to 98.3% with AUC reaching 0.99. The meta-analysis using the Mantel-Haenszel method showed pooled sensitivity of 0.96 with I2 = 80.7% and pooled specificity of 0.95 with I2 = 86.1%. Pooled positive likehood ratio was 15.3 with I2 = 87.3% and negative - was 0.04 with I2 = 78.6%. SROC (symmetric receiver operating characteristics) curve represents AUC = 0.99. For grading the accuracy of AI was lower: sensitivity for Gleason grading ranged from 77% to 87%, and specificity from 82% to 90%.

CONCLUSIONS

The accuracy of AI for PCa identification and grading is comparable to expert pathologists. This is a promising approach which has several possible clinical applications resulting in expedite and optimize pathology reports. AI introduction into common practice may be limited by difficult and time-consuming convolutional neural network training and tuning.

Comparison of EEP and TURP long-term outcomes: systematic review and meta-analysis

OBJECTIVE

To compare long-term reoperation rate and functional outcomes between EEP (endoscopic enucleation of the prostate) and TURP (transurethral resection of the prostate).

EVIDENCE ACQUISITION

A systematic literature review of Medline, Scopus, and Web of Science was conducted with primary outcome assessed being reoperation rate and secondary outcomes after a long term (> 3 years) being functional outcomes or related values (prostate volume, PSA level, etc.).

EVIDENCE SYNTHESIS

Five studies were found with long-term follow-up 4-7 years. EEP reoperation rate ranged from 0 to 1.27%, while from 1.7 to 17.6% for TURP. Meta-analysis showed significantly lower OR for EEP, 0.27 (95% CI 0.24-0.31), with notable homogeneity of the results, I2 = 0%. Long-term Qmax and IPSS were significantly better for EEP. Qmax pooled mean difference was 1.79 (95% CI 1.72-1.86) ml/s with a high concordance among the studies, I2 = 0%. IPSS mean difference -1.24 (95% CI - 1.28 to - 1.2) points, I2 = 57% but QoL did not differ, with mean difference being 0.01 (95% CI - 0.02 to 0.04), I2 = 0%. IIEF-5 score was also significantly better for EEP, mean difference 1.08 (95% CI 1.03-1.13), but heterogeneity was high, I2 = 70%. PSA level and prostate volume were only reported in one study and favored EEP slightly yet statistically significant.

CONCLUSION

EEP had a significantly lower reoperation rate and better functional outcomes (Qmax and IPSS) at long term compared with TURP. It may also be beneficial in terms of IIEF-5, PVR, and PSA level.

Enucleation vs vaporization of benign prostatic hyperplasia: a head-to-head comparison of the various outcomes and complications. A systematic review and meta-analysis

INTRODUCTION

Vaporization of the prostate (VP) and endoscopic enucleation of the prostate (EEP) are reliable and frequently used methods for BPO relief. Both surgeries utilize lasers and EAU recommends them in similar patient cohorts. Our objective was to compare intra- and perioperative results of patients who had undergone VP and EEP.

EVIDENCE ACQUISITION

A systematic literature search was performed in three databases (MEDLINE, Web of Science and Scopus). The detailed search strategy is available at Prospero, CRD42020204739. Primary outcomes were functional results (IPSS, QoL, PVR, Qmax), and secondary outcomes were intraoperative results, postoperative PSA and prostate volume, complications, and recurrence rate.

EVIDENCE SYNTHESIS

VP required less operative time compared to EEP, mean difference=-5.51 (95%CI -7.52; -3.50). IPSS and Qmax for VP were worse after 12-month follow-up, mean difference=0.89 (95%CI 0.52; 1.27) and -3.7 (95%CI -4.56; -2.85), respectively, while QoL did not differ significantly. Postoperative PSA level was higher in the VP group, mean difference=2.28 (95%CI 2.00; 2.55). VP was associated with reduced Clavien-Dindo grade I (OR=4.16; 95%CI 2.96; 5.84) and grade II (OR=3.79; 95%CI 2.25; 6.39) complication rate, especially in terms of the percentage of blood transfusion and transient urinary incontinence. The rate of complications grade IIIa and higher was similar (3 - 6%). Reoperation rate was only estimated in one study and was significantly higher in the PVP group at 60 months of follow-up, 2.7% vs 0%, p<0.05.

CONCLUSIONS

EEP and VP share the efficacy and safety in BPH management. Our meta-analysis shows comparable complication rate in Clavien-Dindo III, VP superiority in operation time, and EEP superiority in long-term functional outcomes and PSA reduction.

Prospective Single-Center Study of SuperPulsed Thulium Fiber Laser in Retrograde Intrarenal Surgery: Initial Clinical Data

INTRODUCTION

The objective of this study was to present our clinical experience of using the thulium fiber laser in retrograde intrarenal surgery (RIRS).

METHODS

A prospective clinical study performed after the IRB approval (Sechenov University, Russia). Patients with stones <30 mm were treated with SuperPulsed thulium fiber laser (SP TFL) (NTO IRE-Polus, Russia) through a 200-μm-diameter fiber. Stone size, density, the duration of the operation, and laser on time (LOT) were measured. Based on the surgeon's feedback, retropulsion and intraoperative visibility were also assessed (Likert scale). Stone-free rates (SFRs) were assessed with a low-dose CT scan 90 days after the operation.

RESULTS

Between January 2018 and December 2019, 153 patients (mean age 54 ± 2.8 years) underwent RIRS with SP TFL (mean stone density 1,020 ± 382 HU). Median stone volume was 279.6 (139.4-615.8) mm3. Median LOT was 2.8 (IQR 1.6-6.6) min with median total energy for stone ablation 4.0 (IQR 2.1-7.17) kJ, median ablation speed was 1.7 (1.0-2.8) mm3/s, median ablation efficacy was 13.3 (7.3-20.9) J/mm3, and energy consumption was 170.3 (59.7-743.3) J/s. Overall, the SFR (at 3 months) was 89%. The overall complication rate was 8.4%. Retropulsion was present in 23 (15.1%) patients. Visibility was estimated as optimal in most patients, with poor visibility reported in only 13 (8.5%) patients.

CONCLUSION

The SP TFL is a safe and efficient tool in lithotripsy, irrespective of the stone type and density. Retropulsion is minimal and visibility is maintained with SP TFL. Nonetheless, further clinical studies are needed to ensure optimal comparison with conventional holmium:YAG lithotripsy.

Retrospective Assessment of Endoscopic Enucleation of Prostate Complications: A Single-Center Experience of More Than 1400 Patients

Introduction: Endoscopic enucleation of the prostate (EEP) is a safe method of treating benign prostatic hyperplasia, regardless of prostate volume and type of applied energy. To date, however, there has been no study that examines complication rates with respect to the type of applied energy. This study aims to address this problem by providing a retrospective analysis of >1400 patients who have undergone prostate enucleation. Materials and Methods: We performed a retrospective analysis of all patients undergoing EEP between 2013 and 2018 at a single tertiary institution. This analysis included patients who had undergone one of three forms of EEP: holmium laser enucleation of the prostate (HoLEP), thulium fiber laser enucleation of the prostate (ThuFLEP), or monopolar enucleation of the prostate (MEP). We compared intraoperative and early postoperative complications, as well as complications at 3 and 6 months follow-up. Results: A total of 1413 patients were included in this study; 36% patients underwent HoLEP, 57.5% had ThuFLEP, and 6.5% MEP. The most frequent complication in the early postoperative period was a mild fever (2.76% of the cases). The morcellation was delayed to a separate stage because of intensive hemorrhaging in 1.4% of the cases. Bladder tamponade was found in 1.1% of the cases. We found no correlation between complication rate and either prostate volume or energy source. Stress urinary incontinence was found in 3.9% of patients at 3 months and in only 1.4% of patients at 6 months after the operation. Urethral stricture at 6 months after the surgery was found in 1.4% of patients, whereas bladder neck sclerosis was found in only 0.9% of these cases. No significant difference was observed between these complication frequencies and any preoperative factors or energy source. Conclusions: All EEP types are safe with equal rates of complications intraoperatively, postoperatively, and at 6 months follow-up.

Endoscopic lithotripsy with a SuperPulsed thulium-fiber laser for ureteral stones: A single-center experience

OBJECTIVES

To estimate the efficacy and safety of SuperPulsed thulium-fiber laser ureteral lithotripsy and to identify optimal laser settings.

METHODS

Patients with solitary stones were prospectively included. Lithotripsy was performed with a SuperPulsed thulium-fiber laser (NTO IRE-Polus, Fryazino, Russia) using a rigid ureteroscope 7.5 Ch (Richard Wolf, Knittlingen, Germany). We analyzed the efficacy of lithotripsy by measuring total energy required for stone disintegration, "laser-on" time, ablation speed, ablation efficacy, and energy consumption. Stone retropulsion and visibility were assessed using a three-point Likert scale. Complications were assessed using the Clavien-Dindo classification system.

RESULTS

A total of 149 patients were included. The mean stone density was 985 ± 360 Hounsfield units, the median (interquartile range) stone volume was 179 (94-357) mm³ . The median (interquartile range) total energy was 1 (0.4-2) kJ, and laser-on time 1.2 (0.5-2.7) min. The median (interquartile range) stone ablation speed was 140 (80-279) mm³ /min, energy for ablation of 1 mm³ was 5.6 (3-9.9) J/mm³ and energy consumption was 0.9 (0.6-1) J/min. A correlation was found between retropulsion and the energy used (r = 0.5, P < 0.001). Multivariable analysis showed energy to be a predictor of increased retropulsion (odds ratio 65.7, 95% confidence interval 1.6-2774.1; P = 0.028). No predictors for worse visibility were identified.

CONCLUSION

The SuperPulsed thulium-fiber laser provides effective and safe lithotripsy during ureteroscopy regardless of stone density. Fiber diameter and laser frequency do not influence visibility or safety. Optimal laser settings are 0.5 J × 30 Hz for fragmentation and 0.15 J × 100 Hz for dusting.

Safety and Short-Term Oncological Outcomes of Thulium Fiber Laser En Bloc Resection of Non-Muscle-Invasive Bladder Cancer: A Prospective Non-Randomized Phase II Trial

BACKGROUND: Ongoing efforts aim at overcoming the challenges of conventional transurethral resection of bladder tumor (TURBT) such as the high recurrence rate, difficulty of pathologic interpretation and complications including wall injury. OBJECTIVE: To prospectively assess the safety and efficacy of Thulium fiber en bloc resection of bladder tumor (Tm-fiber ERBT) compared to TURBT. MATERIALS AND METHODS: The prospective non-randomized study included 129 patients with non-muscle-invasive bladder cancer (NMIBC) divided into two groups: 58 patients underwent conventional TURBT and 71 –Tm-fiber ERBT with FiberLase U1 (NTO IRE-Polus, Russia). Relapse-free survival (RFS), detrusor presence and complication rates were assessed. For multivariable analysis we used the Pearson chi-squared Hosmer-Lemeshow goodness of fit test; to compare survival –Cox regression analysis; for operative data comparison –chi-square test with Fisher’s correction; for survival analysis –the Kaplan–Meier method and logrank test. RESULTS: RFS rates at 3 and 6 months were 84.5% and 67.2% for conventional TURBT versus 97.2% and 91.5% for Tm-fiber ERBT (p = 0.011 and p < 0.001, respectively). Detrusor muscle was present in 58.6% of cases treated with conventional TURBT vs 91.6% for the Tm-fiber ERBT group (p < 0.001). The obturator nerve reflex and bleeding were noted in 17.2% and 10.3% of TURBT cases, respectively; and in none of cases treated with Tm-fiber ERBT. Limitations included the non–randomized nature and the small sample size. CONCLUSIONS: Tm-fiber ERBT seems to be a safe and efficacious treatment option for NMIBC. Tm-fiber ERBT had fewer adverse events, was more likely to secure detrusor muscle in the specimen and resulted in better RFS rates than conventional TURBT. Based on these promising data, we have started a prospective randomized clinical trial comparing en bloc TURBT with conventional TURBT (ClinicalTrials.gov NCT03718754).

Active Surveillance for Intermediate-Risk Prostate Cancer: Systematic Review and Meta-analysis of Current Protocols and Outcomes

INTRODUCTION

Current guidelines allow active surveillance for intermediate-risk prostate cancer patients but do not provide comprehensive recommendations for selection. We performed a systematic review and meta-analysis of outcomes for active surveillance in intermediate- and low-risk groups.

METHODS

We performed a systematic literature search of intermediate-risk localized prostate cancer patients undergoing active surveillance using 3 literature search engines (Medline, Web of Science, and Scopus) over the past 10 years. The primary outcome was the percentage of patients who remain under surveillance. Secondary outcomes included cancer-specific survival, overall survival, and metastasis-free survival. For articles including both low- and intermediate-risk patients undergoing active surveillance, comparisons between the two groups were made.

RESULTS

The proportion of patients who remained on active surveillance was comparable between the low- and intermediate-risk groups after 10 and 15 years' follow-up (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.83-1.14; and OR, 0.86; 95% CI, 0.65-1.13). Cancer-specific survival was worse in the intermediate-risk group after 10 years (OR, 0.47; 95% CI, 0.31-0.69) and 15 years (OR, 0.34; 95% CI, 0.2-0.58). The overall survival rate showed no statistical difference at 5 years' follow-up (OR, 0.84; 95% CI, 0.45-1.57) but was worse in the intermediate-risk group after 10 years (OR, 0.43; 95% CI, 0.35-0.53). Metastases-free survival did not significantly differ after 5 years (OR, 0.55; 95% CI, 0.2-1.53) and was worse in the intermediate-risk group after 10 years (OR, 0.46; 95% CI, 0.28-0.77).

CONCLUSION

Active surveillance could be offered to patients with intermediate-risk prostate cancer. However, they should be informed of the need for regular monitoring and the possibility of discontinuation as a result of a higher rate of progression. Available data indicate that 5-year survival rates between intermediate- and low-risk patients do not differ; 10-year survival rates are worse. To assess the long-term effectiveness and safety of active surveillance, it is necessary to develop unified algorithms for patient selection and management, and to prospectively conduct studies with long-term surveillance.

Dual-Energy Computed Tomography for Stone Type Assessment: A Pilot Study of Dual-Energy Computed Tomography with Five Indices

Purpose: To assess the efficacy of dual-energy CT (DECT) in predicting the composition of urinary stones with a single index (dual energy ratio [DER]) and five indices. Methods: Patients undergoing DECT before active urolithiasis treatment were prospectively enrolled in the study. Predictions of stone composition were made based on discriminant analysis with a single index (DER) and five indices (stone density at 80 and 135 kV, Zeff [the effective atomic number of the absorbent material] of the stone, DER, dual-energy index [DEI] and dual-energy difference [DED]). After extraction, stone composition was evaluated by means of physicochemical analyses (X-ray phase analysis, electron microscopy, wet chemistry techniques, and infrared spectroscopy). Results: A total of 91 patients were included. For calcium oxalate monohydrate (COM) stones, the sensitivity, specificity, and overall accuracy of DECT with one index (DER) were 83.3%, 89.8%, and 86.8%, respectively; for calcium oxalate dihydrate (COD) and calcium phosphate stones-88.2%, 92.9%, and 91.2%, respectively; for uric acid stones-0%, 98.8% and 97.8%, respectively; for struvite stones-60%, 95.3%, and 93.4%, respectively. Discriminant analysis with five indices yielded the following sensitivity, specificity, and overall accuracy: 95.2%, 89.8%, and 92.3% for COM stones, 85.3%, 96.4%, and 92.3% for COD stones, and 100% in all three categories for both uric acid and struvite stones. Conclusions: DECT is a promising tool for stone composition assessment. It allowed for evaluation of chemical composition of all stone types with specificity and accuracy ranging from 85% to 100%. Five DECT indices have shown much better diagnostic accuracy compared to a single DECT index.

Effect of essential amino acid кetoanalogues and protein restriction diet on morphogenetic proteins (FGF-23 and Кlotho) in 3b-4 stages chronic кidney disease patients: a randomized pilot study

BACKGROUND

A low protein diet (LPD) with essential amino acid ketoanalogue supplementation (KA) may contribute in improving of chronic kidney disease (CKD), while the exact mechanisms of KA's effect are not established yet. We have conducted a prospective, randomized, controlled comparative study of LPD + KA and LPD alone in relation to serum Klotho, FGF-23 levels in CKD patients.

METHODS

79 non-diabetic CKD 3b-4 stage patients, compliant with LPD diet (0.6 g/kg of body weight/day), had been selected. The patients were randomized into two groups. The first group (42 patients) received LPD + КA. The second group (37 patients) continued the LРD alone. In addition to routine tests, serum Klotho, FGF-23 levels, as well as bioimpedance analysis, sphygmography (stiffness (augmentation) indices (AI), central (aortal) blood pressure) with a «SphygmaCor» device; echocardiography (valvular calcification score (VCS) and LVMMI), were performed.

RESULTS

There were body mass indices' decrease (p = 0.046), including muscle body mass in men (p = 0.027) and woman (p = 0.044) in the LPD group to the end of study (14th month). In addition, lower FGF-23 (p = 0.029), and higher sKlotho (p = 0.037) were detected in the LPD + KA group compared to the LPD one. The increase in AI (p = 0.034), VCS (p = 0.048), and LVMMI (p = 0.023) was detected more often in the LPD group at the end of study.

CONCLUSION

LPD + KA provides support for nutrition status and contributes to more efficient correction of FGF-23 and Klotho abnormalities that may result in cardiovascular calcification and cardiac remodeling decreasing in CKD. At the same time, a prolonged LPD alone may lead to malnutrition.

Development of 100 Mo -containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search

This paper reports on the development of a technology involving 100 Mo -enriched scintillating bolometers, compatible with the goals of CUPID, a proposed next-generation bolometric experiment to search for neutrinoless double-beta decay. Large mass ( ∼ 1 kg ), high optical quality, radiopure 100 Mo -containing zinc and lithium molybdate crystals have been produced and used to develop high performance single detector modules based on 0.2-0.4 kg scintillating bolometers. In particular, the energy resolution of the lithium molybdate detectors near the Q-value of the double-beta transition of 100 Mo (3034 keV) is 4-6 keV FWHM. The rejection of the α -induced dominant background above 2.6 MeV is better than 8 σ . Less than 10 μ Bq/kg activity of 232 Th ( 228 Th ) and 226 Ra in the crystals is ensured by boule recrystallization. The potential of 100 Mo -enriched scintillating bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only 10 kg × d exposure: the two neutrino double-beta decay half-life of 100 Mo has been measured with the up-to-date highest accuracy as T 1 / 2 = [6.90 ± 0.15(stat.) ± 0.37(syst.)] × 10 18 years . Both crystallization and detector technologies favor lithium molybdate, which has been selected for the ongoing construction of the CUPID-0/Mo demonstrator, containing several kg of 100 Mo .

Adenocarcinoma of the lung with rare insertion mutation in EGFR exon 19 that had partial response to gefitinib: a case report

AIM

Classic activating mutations L858R and deletions in exon 19 (19del) in the gene for epidermal growth factor receptor (EGFR) are associated with sensitivity of the non-small cell lung cancer (NSCLC) to therapy with tyrosine kinase inhibitors (TKI). Insertions in EGFR exon 19 (19ins) are rare mutations in NSCLC; response of cases with 19ins to TKI is not well studied. Here we report a case of NSCLC with 19ins in a Russian patient who was treated with gefitinib. We also overview cases of 19ins reported in the literature.

CASE DESCRIPTION

A 48 years old female Russian patient was diagnosed with adenocarcinoma of the lung (T3N2M1, stage IV). Mutation 19ins was detected in the tumor biopsy by fragment analysis and genotyped by Sanger sequencing as p.I744_K745insKIPVAI. Treatment with gefitinib (250 mg/day) resulted in clinical and radiological improvements scored as partial response that lasted 12 months.

CONCLUSION

Treatment with gefitinib of lung adenocarcinoma that carries mutation EGFR 19ins can result in durable response.

[Case report of the available of interhenotypic recombinant in chronic hepatitis C: the algorithm of individualization of the antiviral therapy]

In this particular case report (in vivo the persistence of HCV intergenotipic recombinant form /2/1b/ peripheral blood mononuclear cells of patient) is an example of optimizing the standard antiviral therapy (PegIntron + Rebetol). In this paper we report a patient infected by HCV 1b and, probably, recombinant 2/1b that is detected in peripheral blood mononuclear cells (PBMC).

CASE DESCRIPTION

Patient S., male, 31 years old admitted in January 2009. HCV viral load in serum before treatment 9,630,000 IU/ml. HCV genotyping by sequencing 5'UTR and NS5A. According to phylogenetic analysis NS5A belongs to 1b (sera and PMBC), 5'UTR from serum to 1b, from PBMC to genotype 2. Due to discordant results recombinant 2/1b in PBMC can be suspected. NS5A interferon sensitivity determining region (ISDR) contains mutation R2218H. Laboratory: ALT 71 U/l, AST 62 U/l, GGT 36 U/l. Liver biopsy: HAI 18, fibrosis 3. Immunohistochemically HCV NS3 was detected in lobules and tracts. Elevated CD16 and CD20 was found in lymphoid follicules of portal tracts. Patient received treatment with pegintron (1.5 mg/kg BW) plus ribavirin (1000 mg/day) for 48 weeks. Virological and biochemical response were achieved on 12 wk and remained until the end of treatment and during follow-up. Liver biopsy after treatment: HAI 6, fibrosis II. Immunohistochemically NS3 was still detected in lobules and tracts, CD16 and CD20 decreased in portal tracts. We also discuss the justification of the selected option treatment strategy (reduced time-course of combination antiviral therapy /28 weeks/ and supplementation of course of antiviral therapy without interferon: a combination of interferon inducer /Cycloferon/ or antiviral drugs /Rebetol/ for another 12 weeks.

Erythrocyte swelling and membrane hole formation in hypotonic media as studied by conductometry

Hypoosmotic swelling of erythrocytes and the formation of membrane holes were studied by measuring the dc conductance (G). In accordance with the theoretical predictions, these processes are manifested by a decrease in G followed by its increase. Thus, unlike the conventional osmotic fragility test, the proposed methodological approach allows investigations of both the kinetics of swelling and the erythrocyte fragility. It is shown that the initial rate of swelling and the equilibrium size of the cells are affected by the tonicity of a hypotonic solution and the membrane rheological properties. Because the rupture of biological membranes is a stochastic process, a time-dependent increase in the conductance follows an integral distribution function of the membrane lifetime. The main conclusion which stems from reported results is that information about rheological properties of red blood cell (RBC) membranes and the resistivity of RBCs to a certain osmotic shock may be extracted from conductance signals.

Observation of the naive-T-odd Sivers effect in deep-inelastic scattering

Azimuthal single-spin asymmetries of leptoproduced pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for a naive-T-odd, transverse-momentum-dependent parton distribution function is deduced from nonvanishing Sivers effects for pi(+), pi(0), and K(+/-), as well as in the difference of the pi(+) and pi(-) cross sections.

Double-hadron leptoproduction in the nuclear medium

The first measurements of double-hadron production in deep-inelastic scattering within the nuclear medium were made with the HERMES spectrometer at DESY HERA using a 27.6 GeV positron beam. By comparing data for deuterium, nitrogen, krypton, and xenon nuclei, the influence of the nuclear medium on the ratio of double-hadron to single-hadron yields was investigated. Nuclear effects on the additional hadron are clearly observed, but with little or no difference among nitrogen, krypton, or xenon, and with smaller magnitude than effects seen on previously measured single-hadron multiplicities. The data are compared with models based on partonic energy loss or prehadronic scattering and with a model based on a purely absorptive treatment of the final-state interactions. Thus, the double-hadron ratio provides an additional tool for studying modifications of hadronization in nuclear matter.

Measurement of the tensor structure function b1 of the deuteron

The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry A(d)zz and the tensor structure function b(d)1 for average values of the Bjorken variable 0.01< <x> <0.45 and of the negative of the squared four-momentum transfer 0.5 GeV2 < <Q2> <5 GeV2. The quantities A(d)zz and b(d)1 are found to be nonzero. The rise of b(d)1 for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.

Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target

Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (phi) and the target spin axis (phi(S)) about the virtual-photon direction and relative to the lepton scattering plane. The extracted Fourier component sin((phi+phi(S))(pi)(UT) is a signal of the previously unmeasured quark transversity distribution, in conjunction with the Collins fragmentation function, also unknown. The component sin((phi-phi(S)(pi)(UT) arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production.

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.

Evidence for quark-hadron duality in the proton spin asymmetry A1

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were scattered off a longitudinally polarized hydrogen target for values of Q2 between 1.2 and 12 GeV2 and values of W2 between 1 and 4 GeV2. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable x. This finding implies that the description of A1 in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of Q2 above 1.6 GeV2.

Q2 dependence of nuclear transparency for exclusive rho0 production

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.