scholarly journals THE PIN GROUPS IN PHYSICS: C, P AND T

2001 ◽  
Vol 13 (08) ◽  
pp. 953-1034 ◽  
Author(s):  
MARCUS BERG ◽  
CÉCILE DeWITT-MORETTE ◽  
SHANGJR GWO ◽  
ERIC KRAMER
Keyword(s):  
Lorentz Group ◽  
Time Reversal ◽  
Vacuum Expectation ◽  
Double Beta Decay ◽  
Spin Group ◽  
Negative Results ◽  
Double Covers ◽  
The Difference ◽  
Positive Results

A simple, but not widely known, mathematical fact concerning the coverings of the full Lorentz group sheds light on parity and time reversal transformations of fermions. Whereas there is, up to an isomorphism, only one Spin group which double covers the orientation preserving Lorentz group, there are two essentially different groups, called Pin groups, which cover the full Lorentz group. Pin(1, 3) is to O(1, 3) what Spin(1, 3) is to SO(1, 3). The existence of two Pin groups offers a classification of fermions based on their properties under space or time reversal finer than the classification based on their properties under orientation preserving Lorentz transformations — provided one can design experiments that distinguish the two types of fermions. Many promising experimental setups give, for one reason or another, identical results for both types of fermions. These negative results are reported here because they are instructive. Two notable positive results show that the existence of two Pin groups is relevant to physics: • In a neutrinoless double beta decay, the neutrino emitted and reabsorbed in the course of the interaction can only be described in terms of Pin(3, 1). • If a space is topologically nontrivial, the vacuum expectation values of Fermi currents defined on this space can be totally different when described in terms of Pin(1, 3) and Pin(3, 1). Possibly more important than the two above predictions, the Pin groups provide a simple framework for the study of fermions; it makes possible clear definitions of intrinsic parities and time reversal; it clarifies colloquial, but literally meaningless, statements. Given the difference between the Pin group and the Spin group it is useful to distinguish their representations, as groups of transformations on "pinors" and 'spinors", respectively. The Pin(1, 3) and Pin(3, 1) fermions are twin-like particles whose behaviors differ only under space or time reversal. A section on Pin groups in arbitrary spacetime dimensions is included.

scholarly journals Serology in COVID-19 – Comparison of Two Methods

2020 ◽  
Author(s):  
Anna Moniuszko-Malinowska ◽  
Wojciech Jelski ◽  
Justyna Dunaj ◽  
Barbara Mroczko ◽  
Piotr Czupryna ◽  
...  
Keyword(s):  
Serological Tests ◽  
S Protein ◽  
Negative Results ◽  
The Difference ◽  
Positive Results

Abstract The aim of our study was to investigate the difference in the anti-SARS-CoV-2 antibodies assessment with two various assays. 127 patients exposed to SARS-CoV-2 were included. Two serological tests were used: SARS-CoV-2 IgG CMIA on the Alinity system (ABBOTT) and LIAISON® SARS-CoV-2 S1/S2 IgG CLIA (DiaSorin). Both assays exhibited 96.85% (123/127 patients) overall compatibility. In 2 cases the positive results in N-based test, were negative in S-based test, and in 2 cases negative results in S-based test were positive in N-based test. Based on the results of our study we concluded that the assessment of anti-SARS-CoV-2 antibodies against N and S protein in population medicine shows comparable usefulness of both tests.

scholarly journals An excess of positive results: Comparing the standard Psychology literature with Registered Reports

2020 ◽  
Author(s):  
Anne M. Scheel ◽  
Mitchell Schijen ◽  
Daniel Lakens
Keyword(s):  
Error Rates ◽  
Type 1 Error ◽  
Negative Results ◽  
Study Results ◽  
Inflated Type ◽  
The Difference ◽  
Psychology Literature ◽  
Positive Results ◽  
Full Population

When studies with positive results that support the tested hypotheses have a higher probability of being published than studies with negative results, the literature will give a distorted view of the evidence for scientific claims. Psychological scientists have been concerned about the degree of distortion in their literature due to publication bias and inflated Type-1 error rates. Registered Reports were developed with the goal to minimise such biases: In this new publication format, peer review and the decision to publish take place before the study results are known. We compared the results in the full population of published Registered Reports in Psychology (N = 71 as of November 2018) with a random sample of hypothesis-testing studies from the standard literature (N = 152) by searching 633 journals for the phrase ‘test* the hypothes*’ (replicating a method by Fanelli, 2010). Analysing the first hypothesis reported in each paper, we found 96% positive results in standard reports, but only 44% positive results in Registered Reports. The difference remained nearly as large when direct replications were excluded from the analysis (96% vs 50% positive results). This large gap suggests that psychologists underreport negative results to an extent that threatens cumulative science. Although our study did not directly test the effectiveness of Registered Reports at reducing bias, these results show that the introduction of Registered Reports has led to a much larger proportion of negative results appearing in the published literature compared to standard reports.

Dynamic Scintigraphy of the Oesophagus in the Evaluation of Reflux Oesophagitis

1990 ◽  
Vol 29 (05) ◽  
pp. 204-209
Author(s):  
B. Ugarković ◽  
D. Ivančević ◽  
D. Babić ◽  
Ž. Babić
Keyword(s):  
Reflux Oesophagitis ◽  
Oesophageal Reflux ◽  
Low Grade ◽  
Time Activity ◽  
The Difference ◽  
Asymptomatic Subjects ◽  
Oesophageal Transit ◽  
Dynamic Scintigraphy ◽  
Positive Results ◽  
Reflux Œsophagitis

A method is presented which combines gastro-oesophageal reflux quantification and oesophageal transit measurement so as to differentiate true reflux from residual oesophageal activity. A group of 33 subjects with gastro-oesophageal reflux symptoms and endoscopically confirmed reflux oesophagitis and a group of 21 asymptomatic subjects with normal oesophageal, gastric and duodenal endoscopic findings were examined. The subjects were given 37 MBq 99mTc-Sn-colloid in saline orally and then scintiscanned dynamically. The gastro-oesophageal quantification was done after transit measurement and after the oesophageal time activity (to detect residual oesophageal activity) reached its minimum. The difference in the reflux indices between the two groups was highly significant. In low-grade oesophagitis measured reflux was lower than in higher grades of disease. Only 4.7% false-positive results were observed with a specificity of 95%, indicating that this method may be superior to methods published earlier.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Depression, pain, and site:

1999 ◽  
Vol 15 (1) ◽  
pp. 10-17
Author(s):  
Molina Omar Franklin ◽  
Tavares Gimenes Pablo ◽  
Aquilino Raphael ◽  
Rank Rise ◽  
Coelho Santos Zeila ◽  
...  
Keyword(s):  
Visual Analogue Scale ◽  
Beck Depression Inventory ◽  
Temporomandibular Disorders ◽  
Analogue Scale ◽  
Epidemiological Data ◽  
Depression Severity ◽  
Internal Joint ◽  
The Difference ◽  
Biomechanical Tests

Objective: To assess the level of depression, severity of pain and pain in single/multiple sites in patients with different severity of bruxing behavior and Temporomandibular Disorders (TMDs). Methods: We evaluated 131 patients with bruxism and TMDs: 20 patients with mild bruxism, 42 patients with moderate bruxism, 45 patients with severe bruxism and 24 patients with extreme bruxism. We used the Beck Depression Inventory (BDI), clinical examination, a questionnaire of clinical epidemiological data, criteria for TMDs and bruxism, palpation of muscles and joints, the Visual Analogue Scale for pain, classification of the occlusion and biomechanical tests to assess for internal joint derangements. Results: The level of depression increased from the mild, to the moderate, severe and extreme bruxing behavior groups, but the difference was significant only from the mild to the extreme group (p<0.001). Pain levels increased from the mild and moderate to the severe and extreme subgroups, but were not statistically significant. Mean number of pain sites increased from the mild, to the moderate, severe and extreme subgroup and the difference was extremely significant (p<0.0001). Conclusion: Levels of depression, severity of pain and pain sites increased with severity of bruxing behavior. A higher number of pain sites with more severe bruxism indicates somatization in bruxers, but a further study using the same protocol and a psychological test for somatization would be indicated to further substantiate these findings.

PET/CT WITH 68GA-PSMA-11 IN DETECTION OF PRIMARY TUMOR AND RECURRENCE OF PROSTATE CANCER

2018 ◽  
Vol 64 (6) ◽  
pp. 799-804
Author(s):  
Darya Ryzhkova ◽  
M. Poyda
Keyword(s):  
Prostate Cancer ◽  
Primary Tumor ◽  
Biochemical Recurrence ◽  
Whole Body ◽  
Negative Results ◽  
Primary Prostate Cancer ◽  
Pet Ct ◽  
The Relationship ◽  
Positive Results ◽  
T Category

Purpose: To study the diagnostic value of PET-CT with 68Ga-PSMA-11 in the diagnosis of a primary prostate cancer, preoperative staging, and the detection of recurrence of prostate cancer (PCa). Methods: 28 patients aged 64.7 ± 8.74 years were included. 10 patients primary prostate cancer, and 18 patients with biochemical recurrence of the disease after radical treatment were examined. All patients underwent PET-CT with 68Ga-PSMA-11 according the whole body protocol. Interpretation of images was performed visually and quantitatively by calculation of SUL max. Results: High focal or diffuse 68Ga-PSMA-11 uptake was found in prostate parenchyma in patients with primary prostate cancer. Additionally metastases in regional lymph nodes were diagnosed in 4 patients and bone metastases were found in one patient. The correlation between 68Ga-PSMA-11 uptake level and Gleason index in the primary tumor (R Spearmen = 0.25, p = 0.57) was not observed. PET-positive results were obtained in 14 patients and PET-negative results in 4 patients with biochemical recurrence of PCa. The relationship between the frequency of PET-positive results and Gleason index was not revealed (R Spearmen = 0.2, p = 0.39). We found a weak but significant correlation between the frequency of PET-positive results and the prostate tumor stage according to the T category (R Spearmen = 0.49, p = 0.049). In patients with low values of PSA (less than 1.0 ng/ml) in 4 out of 9 cases, PET-negative results were obtained. In patients with PSA level more than 1.0 ng/ml PET-positive results were obtained in all cases. Conclusions: PET/CT with 68Ga-PSMA-11 allows to diagnose the primary prostate cancer, to establish the stage of the disease in categories N and M, and also to determine the localization and dissemination of the tumor in patients with biochemical recurrence of prostate cancer. The relationship between 68Ga-PSMA-11 uptake in primary tumor and Gleason index was not found. The probability of obtaining PET-positive results in cases of biochemical recurrence is affected by a PSA level above 1 ng/ml and a high stage of the disease according to the T category (T3-T4).

Description and symmetry of aperiodic crystals

2018 ◽  
Author(s):  
Ted Janssen ◽  
Gervais Chapuis ◽  
Marc de Boissieu
Keyword(s):  
Time Reversal ◽  
Mathematical Concept ◽  
New Materials ◽  
Magnetic Systems ◽  
Atomic Structures ◽  
Modulated Phases ◽  
Quasiperiodic Functions ◽  
Aperiodic Crystals ◽  
Superspace Description

This chapter first introduces the mathematical concept of aperiodic and quasiperiodic functions, which will form the theoretical basis of the superspace description of the new recently discovered forms of matter. They are divided in three groups, namely modulated phases, composites, and quasicrystals. It is shown how the atomic structures and their symmetry can be characterized and described by the new concept. The classification of superspace groups is introduced along with some examples. For quasicrystals, the notion of approximants is also introduced for a better understanding of their structures. Finally, alternatives for the descriptions of the new materials are presented along with scaling symmetries. Magnetic systems and time-reversal symmetry are also introduced.

scholarly journals Diagnostic Performance of Ankle-Brachial Pressure Index in Lower Extremity Arterial Disease

2021 ◽  
Vol 07 (03) ◽  
pp. e132-e137
Author(s):  
Mohammed Alagha ◽  
Thomas M. Aherne ◽  
Ahmed Hassanin ◽  
Adeel S. Zafar ◽  
Doireann P. Joyce ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Sensitivity And Specificity ◽  
False Negative ◽  
Arterial Disease ◽  
Initial Assessment ◽  
Reference Standard ◽  
Lower Extremity Arterial Disease ◽  
Negative Results ◽  
Positive Results ◽  
Arterial Imaging

Abstract Introduction Ankle-brachial pressure indices (ABIs) continue to form the basis of diagnostics for lower extremity arterial disease (LEAD). However, there remains a paucity of data to support its accuracy. This study aims to evaluate its diagnostic sensitivity and specificity using established arterial-imaging modalities as a benchmark. Methods In this retrospective study, a regional, prospectively maintained, vascular laboratory database was interrogated to identify referred patients with arterial disease who underwent concomitant assessment with ABI and lower limb arterial duplex ultrasound (DUS). Duplex acted as the reference standard. Those who had peripheral computed tomography angiogram (CTA) within 3 months of initial assessment were included in a subgroup analysis to correlate ABI with CTA. The primary end point was the sensitivity and specificity of ABI compared with DUS as the reference standard. Results Concomitant assessment was performed in 438 limbs (250 patients) over a 27-month period. The ABI was normal (0.9 to 1.4) in 196 limbs (44.9%) and abnormal in the remaining 241 limbs (55.1%). False-positive results occurred in 83 out of 241 limbs (34.4%), and false-negative results occurred in 54 limbs out of 196 (27.5%). True-positive results were 158 out of 241 limbs (65.6%), whereas true-negative results were 142 out of 196 limbs (72.4%). ABI using DUS as a benchmark identified a sensitivity for peripheral artery disease of 72.3% and a specificity of 69.3%. Concomitant CTA imaging was available in 200 limbs. The sensitivity and specificity of ABI correlated with CTA were 65.5 and 68.8%, respectively. Conclusion ABIs have a moderate predictive value in the diagnosis of LEAD. Normal range outcomes cannot be taken to infer the absence of LEAD and, as such, further arterial imaging in the form of DUS or angiography should be strongly considered in those with suspected underlying disease requiring intervention. Further noninvasive tests such as exercise studies or pulse volume waveforms should be considered, if diagnostic uncertainty exists, in those requiring nonoperative intervention and risk factor control.

scholarly journals The Interpretation of Studies Using the Reading Level Design

1989 ◽  
Vol 21 (4) ◽  
pp. 413-424 ◽  
Author(s):  
Usha Goswami ◽  
Peter Bryant
Keyword(s):  
Reading Disability ◽  
Reading Level ◽  
Chronological Age ◽  
Control Group ◽  
Causal Factors ◽  
Negative Results ◽  
Level Design ◽  
Positive Results

Recent research in reading disability has been strengthened by the addition of a reading level (RL) control group to the more traditional chronological age (CA) control group. However, caution is required in interpreting results from these two kinds of control. Only positive results in a RL match and negative results in a CA match are interpretable; negative results in a CA match and positive results in a RL match are not. Furthermore, the RL control group cannot be used to unambiguously determine between specific deficit and developmental lag interpretations of reading disability. It is argued that the use of the RL control can only ever be a first step in research aimed at delineating the causal factors in reading backwardness.

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