Improved Quantum Query Upper Bounds Based on Classical Decision Trees

We consider the following question in query complexity: Given a classical query algorithm in the form of a decision tree, when does there exist a quantum query algorithm with a speed-up (i.e., that makes fewer queries) over the classical one? We provide a general construction based on the structure of the underlying decision tree, and prove that this can give us an up-to-quadratic quantum speed-up in the number of queries. In particular, our results give a bounded-error quantum query algorithm of cost O(?s) to compute a Boolean function (more generally, a relation) that can be computed by a classical (even randomized) decision tree of size s. This recovers an O(?n) algorithm for the Search problem, for example. Lin and Lin [Theory of Computing\u2716] and Beigi and Taghavi [Quantum\u2720] showed results of a similar flavor. Their upper bounds are in terms of a quantity which we call the "guessing complexity" of a decision tree. We identify that the guessing complexity of a decision tree equals its rank, a notion introduced by Ehrenfeucht and Haussler [Information and Computation\u2789] in the context of learning theory. This answers a question posed by Lin and Lin, who asked whether the guessing complexity of a decision tree is related to any measure studied in classical complexity theory. We also show a polynomial separation between rank and its natural randomized analog for the complete binary AND-OR tree. Beigi and Taghavi constructed span programs and dual adversary solutions for Boolean functions given classical decision trees computing them and an assignment of non-negative weights to edges of the tree. We explore the effect of changing these weights on the resulting span program complexity and objective value of the dual adversary bound, and capture the best possible weighting scheme by an optimization program. We exhibit a solution to this program and argue its optimality from first principles. We also exhibit decision trees for which our bounds are strictly stronger than those of Lin and Lin, and Beigi and Taghavi. This answers a question of Beigi and Taghavi, who asked whether different weighting schemes in their construction could yield better upper bounds

Quantum Policy Gradient Algorithms

Understanding the power and limitations of quantum access to data in machine learning tasks is primordial to assess the potential of quantum computing in artificial intelligence. Previous works have already shown that speed-ups in learning are possible when given quantum access to reinforcement learning environments. Yet, the applicability of quantum algorithms in this setting remains very limited, notably in environments with large state and action spaces. In this work, we design quantum algorithms to train state-of-the-art reinforcement learning policies by exploiting quantum interactions with an environment. However, these algorithms only offer full quadratic speed-ups in sample complexity over their classical analogs when the trained policies satisfy some regularity conditions. Interestingly, we find that reinforcement learning policies derived from parametrized quantum circuits are well-behaved with respect to these conditions, which showcases the benefit of a fully-quantum reinforcement learning framework

Bronchiolitis obliterans organizing pneumonia (BOOP) after thoracic radiotherapy for breast carcinoma

Common complications of thoracic radiotherapy include esophagitis and radiation pneumonitis. However, it is important to be aware of uncommon post-radiotherapy complications such as bronchiolitis obliterans organizing pneumonia (BOOP). We report on two patients with carcinoma of the breast who developed an interstitial lung disease consistent with BOOP. BOOP responds to treatment with corticosteroids and the prognosis is generally good despite of the need for long-term administration of corticosteroids as relapses can occur during tapering of steroids. This report provides guidelines for the evaluation and treatment of patients with pulmonary infiltrates after radiotherapy

Span programs and quantum time complexity

Span programs are an important model of quantum computation due to their correspondence with quantum query and space complexity. While the query complexity of quantum algorithms obtained from span programs is well-understood, it is not generally clear how to implement certain query-independent operations in a time-efficient manner. In this work, we prove an analogous connection for quantum time complexity. In particular, we show how to convert a sufficiently-structured quantum algorithm for f with time complexity T into a span program for f such that it compiles back into a quantum algorithm for f with time complexity Õ(T). This shows that for span programs derived from algorithms with a time-efficient implementation, we can preserve the time efficiency when implementing the span program, which means that span programs capture time, query and space complexities and are a complete model of quantum algorithms. One practical advantage of being able to convert quantum algorithms to span programs in a way that preserves time complexity is that span programs compose very nicely. We demonstrate this by improving Ambainis's variable-time quantum search result using our construction through a span program composition for the OR function

Tumor Ulceration Does Not Fully Explain Sex Disparities in Melanoma Survival among Adolescents and Young Adults

Hypertension in kidney transplant recipients (KTRs) is a risk factor for cardiovascular mortality and graft loss. Data on the prevalence of hypertension and uncontrolled hypertension (uHT) in paediatric and young adult KTRs are scarce. Also, it is unknown whether 'transition' (the transfer from paediatric to adult care) influences control of hypertension. We assessed the prevalence of hypertension and uHT among Dutch paediatric and young adult KTRs and analysed the effects of transition. Additionally, we made an inventory of variations in treatment policies in Dutch transplant centres. Cross-sectional and longitudinal national data from living KTRs a parts per thousand currency sign30 years of age (a parts per thousand yen1-year post-transplant, eGFR > 20 mL/min) were extracted from the 'RICH Q' database, which comprises information about all Dutch KTRs <19 years of age, and the Netherlands Organ Transplant Registry database for adult KTRs (a parts per thousand yen18-30 years of age). We used both upper-limit blood pressure (BP) thresholds for treatment according to Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. uHT was defined as a BP above the threshold. A questionnaire on treatment policies was sent to paediatric and adult nephrologists at eight Dutch transplant centres. Hypertension and uHT were more prevalent in young adult KTRs (86.4 and 75.8%) than in paediatric KTRs (62.7 and 38.3%) according to the KDIGO definition. Time after transplantation was comparable between these groups. Longitudinal analysis showed no evidence of effect of transition on systolic BP or prevalence of uHT. Policies vary considerably between and within centres on the definition of hypertension, BP measurement and antihypertensive treatment. Average BP in KTRs increases continuously with age between 6 and 30 years. Young adult KTRs have significantly more uHT than paediatric KTRs according to KDIGO guidelines. Transition does not influence the prevalence of uHT

Molecular characterization of mutant TP53 acute myeloid leukemia and high-risk myelodysplastic syndrome

Substantial heterogeneity within mutant TP53 acute myeloid leukemia (AML) and myelodysplastic syndrome with excess of blast (MDS-EB) precludes the exact assessment of prognostic impact for individual patients. We performed in-depth clinical and molecular analysis of mutant TP53 AML and MDS-EB to dissect the molecular characteristics in detail and determine its impact on survival. We performed next-generation sequencing on 2200 AML/MDS-EB specimens and assessed the TP53 mutant allelic status (mono- or bi-allelic), the number of TP53 mutations, mutant TP53 clone size, concurrent mutations, cytogenetics, and mutant TP53 molecular minimal residual disease and studied the associations of these characteristics with overall survival. TP53 mutations were detected in 230 (10.5%) patients with AML/MDS-EB with a median variant allele frequency of 47%. Bi-allelic mutant TP53 status was observed in 174 (76%) patients. Multiple TP53 mutations were found in 49 (21%) patients. Concurrent mutations were detected in 113 (49%) patients. No significant difference in any of the aforementioned molecular characteristics of mutant TP53 was detected between AML and MDS-EB. Patients with mutant TP53 have a poor outcome (2-year overall survival, 12.8%); however, no survival difference between AML and MDS-EB was observed. Importantly, none of the molecular characteristics were significantly associated with survival in mutant TP53 AML/MDS-EB. In most patients, TP53 mutations remained detectable in complete remission by deep sequencing (73%). Detection of residual mutant TP53 was not associated with survival. Mutant TP53 AML and MDS-EB do not differ with respect to molecular characteristics and survival. Therefore, mutant TP53 AML/MDS-EB should be considered a distinct molecular disease entity

Prognostic impact of Epstein-Barr virus serostatus in patients with nonmalignant hematological disorders undergoing allogeneic hematopoietic cell transplantation: the study of Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

BackgroundIn patients with acute leukemia, lymphoma and chronic malignancies, donor and/or recipient Epstein-Barr virus (EBV) seropositive status increases the risk of development of chronic graft-versus-host disease (cGVHD) after allo-hematopoietic cell transplantation (allo-HCT), while it has no influence on other transplant outcomes. No data are available on the impact of EBV serostatus on transplant outcomes in patients with nonmalignant hematological disorders. ObjectiveWe analyzed the influence of the recipient's (R) and donor's (D) EBV serostatus on transplant outcomes (overall survival (OS); relapse-free survival (RFS); relapse incidence (RI); nonrelapse mortality (NRM); acute graft-versus-host disease (aGVHD); cGVHD) in patients with nonmalignant hematological disorders undergoing allo-HCT. Patients and MethodsA total of 2,355 allo-HCTs performed between 1997 and 2016 for acquired bone marrow failure or hemoglobinopathies were included in this retrospective Registry megafile Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation (IDWP-EBMT) study. ResultsArray ConclusionsAllo-HCT from EBV-seropositive versus EBV-seronegative donors are at 31% higher risk of cGVHD in patients with nonmalignant hematological disorders undergoing allo-HCT; however this difference is nonsignificant in multivariate analysis

Hematopoietic stem cell transplantation for adolescents and adults with inborn errors of immunity: an EBMT IEWP study.

peer reviewedAllogeneic hematopoietic stem cell transplantation (HSCT) is the gold standard curative therapy for infants and children with many inborn errors of immunity (IEI), but adolescents and adults with IEI are rarely referred for transplant. Lack of published HSCT outcome data outside small, single-center studies and perceived high risk of transplant-related mortality have delayed the adoption of HSCT for IEI patients presenting or developing significant organ damage later in life. This large retrospective, multicenter HSCT outcome study reports on 329 IEI patients (age range, 15-62.5 years at HSCT). Patients underwent first HSCT between 2000 and 2019. Primary endpoints were overall survival (OS) and event-free survival (EFS). We also evaluated the influence of IEI-subgroup and IEI-specific risk factors at HSCT, including infections, bronchiectasis, colitis, malignancy, inflammatory lung disease, splenectomy, hepatic dysfunction, and systemic immunosuppression. At a median follow-up of 44.3 months, the estimated OS at 1 and 5 years post-HSCT for all patients was 78% and 71%, and EFS was 65% and 62%, respectively, with low rates of severe acute (8%) or extensive chronic (7%) graft-versus-host disease. On univariate analysis, OS and EFS were inferior in patients with primary antibody deficiency, bronchiectasis, prior splenectomy, hepatic comorbidity, and higher hematopoietic cell transplant comorbidity index scores. On multivariable analysis, EFS was inferior in those with a higher number of IEI-associated complications. Neither age nor donor had a significant effect on OS or EFS. We have identified age-independent risk factors for adverse outcome, providing much needed evidence to identify which patients are most likely to benefit from HSCT