4,026 research outputs found
Seed, Expand and Constrain: Three Principles for Weakly-Supervised Image Segmentation
We introduce a new loss function for the weakly-supervised training of
semantic image segmentation models based on three guiding principles: to seed
with weak localization cues, to expand objects based on the information about
which classes can occur in an image, and to constrain the segmentations to
coincide with object boundaries. We show experimentally that training a deep
convolutional neural network using the proposed loss function leads to
substantially better segmentations than previous state-of-the-art methods on
the challenging PASCAL VOC 2012 dataset. We furthermore give insight into the
working mechanism of our method by a detailed experimental study that
illustrates how the segmentation quality is affected by each term of the
proposed loss function as well as their combinations.Comment: ECCV 201
Differential Hox expression in murine embryonic stem cell models of normal and malignant hematopoiesis
The Hox family are master transcriptional regulators of developmental processes, including hematopoiesis. The Hox regulators, caudal homeobox factors (Cdx1-4), and Meis1, along with several individual Hox proteins, are implicated in stem cell expansion during embryonic development, with gene dosage playing a significant role in the overall function of the integrated Hox network. To investigate the role of this network in normal and aberrant, early hematopoiesis, we employed an in vitro embryonic stem cell differentiation system, which recapitulates mouse developmental hematopoiesis. Expression profiles of Hox, Pbx1, and Meis1 genes were quantified at distinct stages during the hematopoietic differentiation process and compared with the effects of expressing the leukemic oncogene Tel/PDGFR;2. During normal differentiation the Hoxa cluster, Pbx1 and Meis1 predominated, with a marked reduction in the majority of Hox genes (27/39) and Meis1 occurring during hematopoietic commitment. Only the posterior Hoxa cluster genes (a9, a10, a11, and a13) maintained or increased expression at the hematopoietic colony stage. Cdx4, Meis1, and a subset of Hox genes, including a7 and a9, were differentially expressed after short-term oncogenic (Tel/PDGFR;2) induction. Whereas Hoxa4-10, b1, b2, b4, and b9 were upregulated during oncogenic driven myelomonocytic differentiation. Heterodimers between Hoxa7/Hoxa9, Meis1, and Pbx have previously been implicated in regulating target genes involved in hematopoietic stem cell (HSC) expansion and leukemic progression. These results provide direct evidence that transcriptional flux through the Hox network occurs at very early stages during hematopoietic differentiation and validates embryonic stem cell models for gaining insights into the genetic regulation of normal and malignant hematopoiesis
Rethinking neoadjuvant chemotherapy for breast cancer
Breast cancer is the most common cancer in women worldwide. In 2014, 55 000 women in the UK were given the diagnosis of breast cancer, and 11 000 died.1 Early breast cancer is traditionally treated with surgery, plus radiotherapy and adjuvant systemic therapy as required.
Neoadjuvant chemotherapy for breast cancer is a new strategy that was introduced towards the end of the 20th century with the aim of reducing tumour size. It has four main rationales. Firstly, it should render an otherwise inoperable tumour operable or, secondly, allow more conservative surgery. Thirdly, starting systemic treatment preoperatively was hoped to lead to improved overall survival in patients with locally advanced cancers, who are at high risk of having distant disease. Finally, unlike adjuvant chemotherapy given in the absence of any measurable disease, neoadjuvant chemotherapy gives us the opportunity to observe the tumour shrink both palpably and on imaging, enabling a rapid assessment of clinical response. This could help test responses in vivo to new drug regimens, which could then be used as adjuvant therapies, in so called window of opportunity studies.
A survey of multidisciplinary teams in Australia, Germany, Italy, the UK, and the US found that 7-27% of new breast cancers are treated with neoadjuvant chemotherapy (Saunders C, Cody H, Kolberg HC, et al, personal communication, 2017). With 1.7 million women receiving diagnoses annually, this translates into 120 000-460 000 women receiving neoadjuvant chemotherapy worldwide.1
Although data indicate that the first rationale remains valid, the others have not led to the desired outcomes. More conservative surgery after neoadjuvant chemotherapy can result in a higher rate of local recurrence, and, despite the earlier initiation of systemic treatment, no improvement in survival has been seen.234 Furthermore, neoadjuvant chemotherapy may not help test novel chemotherapies—although primary tumour response is a good indicator of prognosis for a particular treatment, it is counterintuitively a poor surrogate marker for the overall survival benefit when evaluating novel chemotherapy regimens. Finally, for 40-80% of patients, even the best neoadjuvant chemotherapy regimens extend the period the cancer remains in the breast and can make surgery more difficult, as the tumour is less easily palpable and the axillary lymph nodes are less distinct. We question the wisdom of the current widespread use of neoadjuvant chemotherapy
Accelerated Proximal Iterative re-Weighted Alternating Minimization for Image Deblurring
The quadratic penalty alternating minimization (AM) method is widely used for
solving the convex total variation (TV) image deblurring problem.
However, quadratic penalty AM for solving the nonconvex nonsmooth , TV image deblurring problems is less studied. In this paper, we
propose two algorithms, namely proximal iterative re-weighted AM
(PIRL1-AM) and its accelerated version, accelerated proximal iterative
re-weighted AM (APIRL1-AM) for solving the nonconvex nonsmooth
TV image deblurring problem. The proposed algorithms are derived from
the proximal iterative re-weighted (IRL1) algorithm and the proximal
gradient algorithm. Numerical results show that PIRL1-AM is effective in
retaining sharp edges in image deblurring while APIRL1-AM can further provide
convergence speed up in terms of the number of algorithm iterations and
computational time
Global Gene Expression Analysis in the Livers of Rat Offspring Perinatally Exposed to Low Doses of 2,2′,4,4′-Tetrabromodiphenyl Ether
BACKGROUND: Polybrominated diphenyl ethers are a group of flame-retardant chemicals appearing increasingly in the environment. Their health effects and mechanisms of toxicity are poorly understood.
OBJECTIVES: We screened for the sensitive effects and mechanisms of toxicity of 2,2 ,4,4 -tetra-bromodiphenyl ether (BDE-47) by analyzing the gene expression profile in rats exposed to doses comparable to human exposure.
METHODS: Wistar dams were exposed to vehicle or BDE-47 (0.002 and 0.2 mg/kg body weight) every fifth day from gestation day 15 to postnatal day 20 by injections to caudal vein. Total RNA was extracted from the livers of pups and hybridized to the whole-genome RNA expression micro-arrays. The list of genes 2-fold differentially expressed was exported to PANTHER and Ingenuity Systems for analysis of enriched ontology groups and molecular pathways.
RESULTS: Oxidoreductase and transferase protein families were enriched in exposed rats as were these biological process categories: carbohydrate metabolism; electron transport; and lipid, fatty acid, and steroid metabolism. Four signaling pathways (cascades of activation of drug-metabolizing enzymes) and 10 metabolic pathways were significantly enriched. Drug-metabolizing enzymes appear to be regulated by BDE-47 through an aryl hydrocarbon receptor-independent mechanism. Direct interaction with retinoid X receptor or its upstream cascade may be involved. The main metabolic effects consisted of activation of metabolic pathways: alpha- and omega-oxidation of fatty acids, glycolysis, and starch hydrolysis.
CONCLUSIONS: Altered expression of genes involved in metabolic and signaling pathways and functions of the organism occurs after perinatal exposure of rat offspring to BDE-47 at doses relevant for the general population
Efficient and long-lived quantum memory with cold atoms inside a ring cavity
Quantum memories are regarded as one of the fundamental building blocks of
linear-optical quantum computation and long-distance quantum communication. A
long standing goal to realize scalable quantum information processing is to
build a long-lived and efficient quantum memory. There have been significant
efforts distributed towards this goal. However, either efficient but
short-lived or long-lived but inefficient quantum memories have been
demonstrated so far. Here we report a high-performance quantum memory in which
long lifetime and high retrieval efficiency meet for the first time. By placing
a ring cavity around an atomic ensemble, employing a pair of clock states,
creating a long-wavelength spin wave, and arranging the setup in the
gravitational direction, we realize a quantum memory with an intrinsic spin
wave to photon conversion efficiency of 73(2)% together with a storage lifetime
of 3.2(1) ms. This realization provides an essential tool towards scalable
linear-optical quantum information processing.Comment: 6 pages, 4 figure
The Effects of Surfaces and Surface Passivation on the Electrical Properties of Nanowires and Other Nanostructures: Time-Resolved Terahertz Spectroscopy Studies
The electrical properties of nanomaterials are strongly influenced by their surfaces, which in turn are strongly influenced by device processing and passivation procedures. Optical pump-terahertz probe spectroscopy is ideal for measuring the native properties of these materials, determining the changes induced by device processing, and studying the effectiveness of surface passivation procedures. Here we study the electronic properties of III-V nanowires and other nanomaterials in both their native and encapsulated/integrated states, which is uniquely possible with terahertz spectroscopy
Links between traumatic brain injury and ballistic pressure waves originating in the thoracic cavity and extremities
Identifying patients at risk of traumatic brain injury (TBI) is important
because research suggests prophylactic treatments to reduce risk of long-term
sequelae. Blast pressure waves can cause TBI without penetrating wounds or
blunt force trauma. Similarly, bullet impacts distant from the brain can
produce pressure waves sufficient to cause mild to moderate TBI. The fluid
percussion model of TBI shows that pressure impulses of 15-30 psi cause mild to
moderate TBI in laboratory animals. In pigs and dogs, bullet impacts to the
thigh produce pressure waves in the brain of 18-45 psi and measurable injury to
neurons and neuroglia. Analyses of research in goats and epidemiological data
from shooting events involving humans show high correlations (r > 0.9) between
rapid incapacitation and pressure wave magnitude in the thoracic cavity. A case
study has documented epilepsy resulting from a pressure wave without the bullet
directly hitting the brain. Taken together, these results support the
hypothesis that bullet impacts distant from the brain produce pressure waves
that travel to the brain and can retain sufficient magnitude to induce brain
injury. The link to long-term sequelae could be investigated via
epidemiological studies of patients who were gunshot in the chest to determine
whether they experience elevated rates of epilepsy and other neurological
sequelae
Form factors at strong coupling via a Y-system
We compute form factors in planar N=4 Super Yang-Mills at strong coupling.
Namely we consider the overlap between an operator insertion and 2n gluons.
Through the gauge/string duality these are given by minimal surfaces in AdS
space. The surfaces end on an infinite periodic sequence of null segments at
the boundary of AdS. We consider surfaces that can be embedded in AdS_3. We
derive set of functional equations for the cross ratios as functions of the
spectral parameter. These equations are of the form of a Y-system. The integral
form of the Y-system has Thermodynamics Bethe Ansatz form. The area is given by
the free energy of the TBA system or critical value of Yang-Yang functional. We
consider a restricted set of operators which have small conformal dimension
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