{"title":"Minimal Realizations and Determinantal Representations in the Indefinite Setting","authors":"Joshua D. Jackson, Hugo J. Woerdeman","doi":"10.1007/s00020-022-02697-1","DOIUrl":"https://doi.org/10.1007/s00020-022-02697-1","url":null,"abstract":"<p>For a signature matrix <i>J</i>, we show that a rational matrix function <i>M</i>(<i>z</i>) that is strictly <i>J</i>-contractive on the unit circle <span>({{mathbb {T}}})</span>, has a strict <span>({tilde{J}}oplus J)</span>-contractive realization <span>(begin{bmatrix} A &{} B C &{} D end{bmatrix})</span> for an appropriate signature matrix <span>({tilde{J}})</span>; that is, <span>( M(z) = D +zC (I -zA)^{-1} B )</span>. As an application, we use this result to show that a two variable polynomial <span>(p(z_1,z_2))</span> of degree <span>((n_1,n_2))</span>, <span>(n_2=1)</span>, without roots on <span>({ (0,0) } cup ({{mathbb {T}}} times { 0 } ) cup {{mathbb {T}}}^2)</span> allows a determinantal representation </p><span>$$begin{aligned} p(z_1, z_2) = p(0,0) det (I_{n_1+1} - K Z), Z = z_1 I_{n_1} oplus z_2 I_{n_2} , end{aligned}$$</span>(1)<p>where <i>K</i> is a strict <span>({tilde{J}}oplus J)</span>-contraction. This provides first evidence of a new conjecture that a two variable polynomial <span>(p(z_1,z_2))</span> of degree <span>((n_1,n_2))</span> has a determinantal representation (1) with <i>K</i> a strict <span>({tilde{J}}oplus J)</span>-contraction if and only if <span>(p(z_1,z_2))</span> has no roots in <span>({ (0,0) } cup {{mathbb {T}}}^2)</span>.</p>","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":"72 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138516100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Correction to: Weak Product Spaces of Dirichlet Series","authors":"Ole Fredrik Brevig, Karl-Mikael Perfekt","doi":"10.1007/s00020-023-02736-5","DOIUrl":"https://doi.org/10.1007/s00020-023-02736-5","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":"95 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43385659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Invariant Subspaces of Idempotents on Hilbert Spaces","authors":"N. Bala, Nirupam Ghosh, J. Sarkar","doi":"10.1007/s00020-022-02723-2","DOIUrl":"https://doi.org/10.1007/s00020-022-02723-2","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47887256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Essential Spectrum and Feller Type Properties","authors":"A. BenAmor, B. Güneysu, P. Stollmann","doi":"10.1007/s00020-023-02732-9","DOIUrl":"https://doi.org/10.1007/s00020-023-02732-9","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":"95 1","pages":"1-20"},"PeriodicalIF":0.8,"publicationDate":"2022-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41738357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Feynman’s Operational Calculus with Arbitrary Measures: An Evolution Equation in the General Case and Examples","authors":"L. Nielsen","doi":"10.1007/s00020-022-02694-4","DOIUrl":"https://doi.org/10.1007/s00020-022-02694-4","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47155979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Norms of Basic Operators in Vector Valued Model Spaces and de Branges Spaces","authors":"Kousik Dhara, H. Dym","doi":"10.1007/s00020-022-02719-y","DOIUrl":"https://doi.org/10.1007/s00020-022-02719-y","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43478935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Commutative Algebras of Toeplitz Operators on the Bergman Space Revisited: Spectral Theorem Approach","authors":"G. Rozenblum, N. Vasilevski","doi":"10.1007/s00020-022-02706-3","DOIUrl":"https://doi.org/10.1007/s00020-022-02706-3","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41710999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Interpersonal Approach to the Treatment of Social Anxiety Disorder (Social Phobia): A Component Analysis.","authors":"Ariel Stravynski, Lise Lachance","doi":"10.5152/pcp.2022.21246","DOIUrl":"10.5152/pcp.2022.21246","url":null,"abstract":"<p><strong>Background: </strong>Most treatments of social anxiety disorder aim at anxiety reduction. To what extent this leads to improved social functioning remains unclear. An effective alternative aiming primarily at social functioning- the Interpersonal Approach- is available. The present study sought to identify its active ingredients.</p><p><strong>Methods: </strong>This is a randomized controlled study; 102 social anxiety disorder individuals were randomly assigned to 3 versions of the Interpersonal Approach. A total of 76 patients completed treatment and 67, a 1-year follow-up. The patients met Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria for social anxiety disorder. The study was carried out in an experimental clinic for the treatment of social anxiety disorder at the Research Center of Louis-H. Lafontaine Hospital in Montreal, Canada.</p><p><strong>Results: </strong>No clinically meaningful change occurred during the waiting list. A significant and equivalent improvement was obtained in all treatment conditions in social functioning, anxiousness, and general psychopathology, maintaining over a 12-month follow-up. Remission rates improved progressively with 54% remission at 1-year follow-up. All variants of the Interpersonal Approach resulted in similar improvements.</p><p><strong>Conclusion: </strong>The Interpersonal Approach in all its versions has proved to be effective in reducing anxiety complaints and improving social functioning. The combined improvement in these 2 outcomes accounts for the significant remission rates seen at 1-year follow-up. Two active features were common to all: (1) targeting and ultimately dissolving long-standing habits of self-protection across various spheres of life and (2) fostering participatory interpersonal patterns of behavior, enacted by patients systematically and repeatedly between sessions.</p>","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":"15 1","pages":"33-44"},"PeriodicalIF":0.7,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11099670/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73092757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Limit Laws for R-diagonal Variables in a Tracial Probability Space","authors":"Cong Zhou","doi":"10.1007/s00020-022-02689-1","DOIUrl":"https://doi.org/10.1007/s00020-022-02689-1","url":null,"abstract":"","PeriodicalId":13658,"journal":{"name":"Integral Equations and Operator Theory","volume":"94 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"52032449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}