To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We develop the concept of character level for the complex irreducible characters of finite, general or special, linear and unitary groups. We give characterizations of the level of a character in terms of its Lusztig label and in terms of its degree. Then we prove explicit upper bounds for character values at elements with not-too-large centralizers and derive upper bounds on the covering number and mixing time of random walks corresponding to these conjugacy classes. We also characterize the level of the character in terms of certain dual pairs and prove explicit exponential character bounds for the character values, provided that the level is not too large. Several further applications are also provided. Related results for other finite classical groups are obtained in the sequel [Guralnick et al. ‘Character levels and character bounds for finite classical groups’, Preprint, 2019, arXiv:1904.08070] by different methods.
Governments are often punished for negative events such as economic downturns and financial shocks. However, governments can address such shocks with salient policy responses that might mitigate public punishment. We use three high-quality nationally representative surveys collected around a key event in the history of the Dutch economy, namely the outbreak of the financial crisis in 2008, to examine how voters responded to a salient government bailout. The results illustrate that governments can get substantial credit for pursuing a bailout in the midst of a financial crisis. Future research should take salient policy responses into account to fully understand the public response to the outbreak of financial and economic crises.
To assess variability in antimicrobial use and associations with infection testing in pediatric ventilator-associated events (VAEs).
Descriptive retrospective cohort with nested case-control study.
Pediatric intensive care units (PICUs), cardiac intensive care units (CICUs), and neonatal intensive care units (NICUs) in 6 US hospitals.
Children≤18 years ventilated for≥1 calendar day.
We identified patients with pediatric ventilator-associated conditions (VACs), pediatric VACs with antimicrobial use for≥4 days (AVACs), and possible ventilator-associated pneumonia (PVAP, defined as pediatric AVAC with a positive respiratory diagnostic test) according to previously proposed criteria.
Among 9,025 ventilated children, we identified 192 VAC cases, 43 in CICUs, 70 in PICUs, and 79 in NICUs. AVAC criteria were met in 79 VAC cases (41%) (58% CICU; 51% PICU; and 23% NICU), and varied by hospital (CICU, 20–67%; PICU, 0–70%; and NICU, 0–43%). Type and duration of AVAC antimicrobials varied by ICU type. AVAC cases in CICUs and PICUs received broad-spectrum antimicrobials more often than those in NICUs. Among AVAC cases, 39% had respiratory infection diagnostic testing performed; PVAP was identified in 15 VAC cases. Also, among AVAC cases, 73% had no associated positive respiratory or nonrespiratory diagnostic test.
Antimicrobial use is common in pediatric VAC, with variability in spectrum and duration of antimicrobials within hospitals and across ICU types, while PVAP is uncommon. Prolonged antimicrobial use despite low rates of PVAP or positive laboratory testing for infection suggests that AVAC may provide a lever for antimicrobial stewardship programs to improve utilization.
Reduced absorption capacity in patients with intestinal resections (IR) could result in malabsorption of fat-soluble components like carotenoids, which are of clinical interest in relation to visual health. In this case cohort, we investigated the association between IR and serum lutein, zeaxanthin, β-carotene and macular pigment optical density, when compared with healthy controls. Ten patients with IR and twelve healthy controls were included in the study. Baseline characteristics were comparable between groups, except for higher serum TAG (P < 0·05) and shorter bowel length (P < 0·0001) in the group with IR. Serum lutein, zeaxanthin, β-carotene and macular pigment optical density were >15 % lower in the patient group compared with healthy controls (P < 0·05, adjusted for age) and, in the case of serum lutein and zeaxanthin, also for dietary intake of carotenoids. Results suggest that for a test of macular carotenoid supplementation, subjects with a potentially clinically significant carotenoid deficit could be recruited among patients with IR.
Adult ventilator-associated event (VAE) definitions include ventilator-associated conditions (VAC) and subcategories for infection-related ventilator-associated complications (IVAC) and possible ventilator-associated pneumonia (PVAP). We explored these definitions for children.
Pediatric, cardiac, or neonatal intensive care units (ICUs) in 6 US hospitals
Patients ≤18 years old ventilated for ≥1 day
We identified patients with pediatric VAC based on previously proposed criteria. We applied adult temperature, white blood cell count, antibiotic, and culture criteria for IVAC and PVAP to these patients. We matched pediatric VAC patients with controls and evaluated associations with adverse outcomes using Cox proportional hazards models.
In total, 233 pediatric VACs (12,167 ventilation episodes) were identified. In the cardiac ICU (CICU), 62.5% of VACs met adult IVAC criteria; in the pediatric ICU (PICU), 54.2% of VACs met adult IVAC criteria; and in the neonatal ICU (NICU), 20.2% of VACs met adult IVAC criteria. Most patients had abnormal white blood cell counts and temperatures; we therefore recommend simplifying surveillance by focusing on “pediatric VAC with antimicrobial use” (pediatric AVAC). Pediatric AVAC with a positive respiratory diagnostic test (“pediatric PVAP”) occurred in 8.9% of VACs in the CICU, 13.3% of VACs in the PICU, and 4.3% of VACs in the NICU. Hospital mortality was increased, and hospital and ICU length of stay and duration of ventilation were prolonged among all pediatric VAE subsets compared with controls.
We propose pediatric AVAC for surveillance related to antimicrobial use, with pediatric PVAP as a subset of AVAC. Studies on generalizability and responsiveness of these metrics to quality improvement initiatives are needed, as are studies to determine whether lower pediatric VAE rates are associated with improvements in other outcomes.
be nontrivial words in free groups
, respectively. We prove that, for all sufficiently large finite nonabelian simple groups
, there exist subsets
. In particular, if
is any nontrivial word and
is a sufficiently large finite nonabelian simple group, then
contains a thin base of order
. This is a nonabelian analog of a result of Van Vu [‘On a refinement of Waring’s problem’, Duke Math. J. 105(1) (2000), 107–134.] for the classical Waring problem. Further results concerning thin bases of
are established for any finite group and for any compact Lie group
There is controversy about the implications of relatively small average drug–placebo differences observed in randomised controlled trials of antidepressant medications.
To investigate whether efficacy is better understood as a large effect in a subgroup of patients.
The mixture model was used to identify patient subgroups (patients benefiting or not benefiting from treatment) to directly model the skewness of Montgomery–åsberg Depression Rating Scale (MADRS) scores at week 8.
The MADRS scores improved by 15.9 points (95% CI 15.2–16.6) among patients who benefited from treatment. The proportion of patients who benefited from escitalopram and not from placebo treatment was 19.5%, corresponding to a number needed to treat of 5.
This model gave a considerably better fit to the data than the analysis of covariance model in which all patients were assumed to benefit from treatment. The small average antidepressant–placebo difference obscures a much larger effect in a clinically meaningful subgroup of patients.
Inodilators are used in the treatment of low cardiac output, mainly after cardiac surgery. At present, there is little knowledge of the effect of inodilators in the newborn heart. Immediately after birth and in the neonatal period, the metabolism and physiology of the heart undergo major changes. We hypothesised that effects of the inodilators milrinone and levosimendan on myocardial contractility and haemodynamics under normal physiological conditions were age dependent. Animal studies were conducted on 48 pigs using a closed-chest biventricular conductance catheter method. Pigs in two age groups, that is, 5–6 days and 5–6 weeks, were assigned to milrinone, levosimendan, or a control group. We observed that both milrinone – 19.2% with a p value of 0.05 – and levosimendan – 25.7% with a p value of 0.03 compared with the control group increased cardiac output, as well as myocardial contractility with a maximum pressure development over time: milrinone 28.2%, p = 0.01 and levosimendan 19.4%, p = 0.05. Milrinone improved diastolic performance (p < 0.05) in the left ventricle in the 5–6-week-old animals. In the newborn animals, neither of the inodilators increased ventricular contractility or cardiac output; however, we observed a significant decrease in the mean arterial pressure: milrinone 34.6%, p < 0.01 and levosimendan 30.1%, p = 0.02. Both inodilators demonstrated age-dependent haemodynamic effects, and it is noteworthy that neither milrinone nor levosimendan was able to increase cardiac output in the newborn heart.
Two-Photon initiated polymerization (TPIP) has shown great promise for fabrication of complex micro- and nano-structures. The method has been used to fabricate such structures over small areas (< 1 mm2) because of slow fabrication speeds and resulting long fabrication times. In order for TPIP to reach practical application in a commercial setting fabrication times need to be reduced by orders of magnitude. We report results on a highly photosensitive initiation system for photoresists based on free radical and cationic polymerization, where photosensitivity is increased 102- to 103-fold compared to previously reported photoinitiation systems. Threshold writing speeds are determined for critical exposure conditions, including laser power, type and concentration of photoinitiation system, and photoresist type. Surface roughness, a critical parameter in applications such as optics and microfluidics, for example, is also used to determine threshold writing speed. The utility of the approach is demonstrated by making a cell phone keypad light guide from a microreplication tool fabricated using the highly photosensitive photoresist.
Modal and mixed transition systems are specification formalisms that allow the mixing of over- and under-approximation. We discuss three fundamental decision problems for such specifications:
—whether a set of specifications has a common implementation;
—whether an individual specification has an implementation; and
—whether all implementations of an individual specification are implementations of another one.
For each of these decision problems we investigate the worst-case computational complexity for the modal and mixed cases. We show that the first decision problem is EXPTIME-complete for both modal and mixed specifications. We prove that the second decision problem is EXPTIME-complete for mixed specifications (it is known to be trivial for modal ones). The third decision problem is also shown to be EXPTIME-complete for mixed specifications.
We prove that, for any prime ℓ and any even integer n, there are infinitely many exponents k for which appears as a Galois group over . This generalizes a result of Wiese from 2006, which inspired this paper.
We establish isomorphisms between certain specializations of BMW algebras and the symmetric squares of Temperley–Lieb algebras. These isomorphisms imply a link-polynomial identity due to W. B. R. Lickorish. As an application, we compute the closed images of the irreducible braid group representations factoring over these specialized BMW algebras.
Maternal depression is prevalent, and puts children at risk. Little
evidence addresses whether treatment for maternal depression is sufficient
to improve child outcomes. An experiment was conducted testing whether
psychotherapeutic treatment for mothers, suffering from major depression
in the postpartum period, would result in improved parenting and child
outcomes. Participants included depressed women randomly assigned to
interpersonal psychotherapy (n = 60) or to a waitlist (n
= 60), and a nondepressed comparison group (n = 56). At 6 months,
depressed mothers were less responsive to their infants, experienced more
parenting stress, and viewed their infants more negatively than did
nondepressed mothers. Treatment affected only parenting stress, which
improved significantly but was still higher than that for nondepressed
mothers. Eighteen months later, treated depressed mothers still rated
their children lower in attachment security, higher in behavior problems,
and more negative in temperament than nondepressed mothers. Initial
response to treatment did not predict reduced risk for poor child
outcomes. Early maternal negative perceptions of the child predicted
negative temperament and behavior problems 18 months after treatment.
Treatment for depression in the postpartum period should target the
mother–infant relationship in addition to the mothers'
depressive symptoms.This work was supported
by National Institute of Mental Health Grant MH 50524 to the second
author. Additional support was provided by NIMH Traineeship MH 15755,
through the Institute of Child Development, University of Minnesota and by
the Canada Research Chairs program. We gratefully acknowledge the
assistance of Grazyna Kochanska, our numerous undergraduate coders, and
our generous and dedicated participants.
This is a copy of the slides presented at the meeting but not formally written up for the volume.
Superparamagnetic iron oxide (SPIO) nanoparticles are prevalent as nanoprobes for molecular magnetic resonance imaging (MRI), providing positive or negative contrast by locally affecting the relaxation of water protons. Fe3O4 nanoparticles are commonly used as a negative MRI contrast agent, implementing various surface functionalization techniques to provide molecular targeting to biological macromolecules. The authors recently demonstrated targeting of cancer antigen 125 (CA125) with differentiable MRI contrast in human ovarian cancer cell lines using monoclonal antibodies covalently conjugated to phospholipid micelle encapsulated 10 nm single crystalline SPIO nanoparticles, demonstrating molecular targeting capabilities via surface functionalization . While molecular targeting of SPIO nanoparticles has been thoroughly demonstrated, the effects of surface modifications have not been studied in regard to proton relaxation. The authors will present spin-lattice (T1) and spin-spin (T2) proton relaxometry of SPIO nanoparticles with varying surface chemistries. The effects of surface modification on T1 and T2 relaxation have not been thoroughly investigated, and results recently reported by the authors indicate a correlation of spin-spin relaxation with SPIO nanoparticle hydrodynamic radius . T1 and T2 relaxometry (Varian 300 MHz NMR) of polyethylene glycol modified (PEGylated) phospholipid micelle encapsulated SPIO nanoparticles and covalently PEGylated SPIO nanoparticles for varying hydrodynamic radii will be presented. These results are of particular interest to molecular imaging applications due to the common practice of SPIO nanoparticle PEGylation to improve biocompatibility. The authors will also present results of magnetic anisotropy studies with respect to proton relaxation by SPIO nanoparticles. Recent work by Roch et al emphasizes the role of magnetic anisotropy in the proton relaxation mechanism of SPIO nanoparticles . The authors have synthesized monodisperse Fe3-xCoxO4 nanoparticles with similar properties to SPIO. Cobalt substitution in SPIO nanoparticles increases the magnetic anisotropy of the SPIO nanoparticles, thus affecting the proton relaxation. The authors will present T1 and T2 relaxometry (Varian 300 MHz NMR) of Fe3-xCoxO4 nanoparticles and corresponding SQUID (superconducting quantum interference device) magnetic anisotropy measurements (Quantum Design, MPMS-7). The results of this study elucidate the role of magnetic anisotropy in the proton relaxation mechanism and demonstrates the feasibility of Fe3-xCoxO4 nanoparticles as a T2 contrast agent.1. Larsen BA et al, Proceedings of the 5th Annual Meeting of Molecular Imaging, 20062. Barker AJ, Larsen BA et al, Proceedings of the ASME SBC, 20063. Roch et al, Journal of Mag Res Imaging 14, pp 94-96, 2001.
Polycrystalline SiC nanowires and composite Si nanowire-SiC nanograin structures have been synthesized using a combined catalytic chemical vapor deposition and carburization method. Si nanowires are grown at low temperature (550-650 C) and subsequently carburized at 1100-1200 C in a methane/hydrogen or propane/hydrogen environment. Thermochemical calculations showed that the Si carburization is thermodynamically favorable over a wide tempareture range, whereas our studies showed that the Si nanowire carburization is kinetically limited below ∼1100 °C. Partially carburized nanowires contained distinct SiC nanosized grains on the Si nanowire surface, whereas fully carburized nanowires were polycrystalline 3C SiC with grain sizes of ∼ 50-100 nm.
The zeta function of a complex variety is a power series whose nth coefficient is the nth symmetric power of the variety, viewed as an element in the Grothendieck ring of complex varieties. We prove that the zeta function of a surface is rational if and only if the Kodaira dimension of the surface is negative.