496 research outputs found
Signals of New Gauge Bosons in Gauged Two Higgs Doublet Model
Recently a gauged two Higgs doublet model, in which the two Higgs doublets
are embedded into the fundamental representation of an extra local
group, is constructed. Both the new gauge bosons and are electrically neutral. While can be singly produced at
colliders, , which is heavier, must be pair produced. We
explore the constraints of using the current Drell-Yan type data
from the Large Hadron Collider. Anticipating optimistically that can
be discovered via the clean Drell-Yan type signals at high luminosity upgrade
of the collider, we explore the detectability of extra heavy fermions in the
model via the two leptons/jets plus missing transverse energy signals from the
exotic decay modes of . For the pair production in
a future 100 TeV proton-proton collider, we demonstrate certain kinematical
distributions for the two/four leptons plus missing energy signals have
distinguishable features from the Standard Model background. In addition,
comparisons of these kinematical distributions between the gauged two Higgs
doublet model and the littlest Higgs model with T-parity, the latter of which
can give rise to the same signals with competitive if not larger cross
sections, are also presented.Comment: 39 pages, 23 figures, 7 tables and two new appendixes, to appear in
EPJ
Cortical development & plasticity in the FMRP KO mouse
Autism is one of the leading causes of human intellectual disability (ID).
More than 1% of the human population has autism spectrum disorders (ASDs), and it
has been estimated that over 50% of those with ASDs also have ID. Fragile X
syndrome (FXS) is the most common inherited form of mental retardation and is the
leading known genetic cause of autism, affecting approximately 1 in 4000 males and
1 in 8000 females. Approximately 30% of boys with FXS will be diagnosed with
autism in their later lives.
The cause of FXS is through an over-expansion of the CGG trinucleotide
repeat located at the 5’ untranslated region of the FMR1 gene, leading to
hypermethylation of the surrounding sequence and eventually partially or fully
silencing of the gene. Therefore, the protein product of the gene, fragile X mental
retardation protein (FMRP), is reduced or missing.
As a single-gene disorder, FXS offers a scientifically tractable way to
examine the underlying mechanism of the disease and also shed some light on
understanding ASD and ID. The mouse model of FXS (Fmr1−/y mice) is widely
accepted and used as a good model, offering good structural and face validity. Since
a primary deficit of FXS is believed to be altered neuronal communication, in this
thesis I examined white matter tract and dendritic spine abnormalities in the mouse
model of FXS. Loss of FMRP does not alter the gross morphology of the white
matter. However, recent brain imaging studies indicated that loss of FMRP could
lead to some minute abnormalities in different major white matter tracts in the human
brain. The gross white matter morphology and myelination was unaltered in the
Fmr1−/y mice, however, a small but significant increase of axon diameter in the
corpus callosum (CC) was found compared to wild-type (WT) controls. Our
computation model suggested that the increase of axon diameter in the Fmr1−/y mice
could lead to an increase of conduction velocity in these animals.
One of the key phenotypes reported previously in the loss of FMRP is the
increase of “immature” dendritic spines. The increase of long and thin spines was
reported in several brain regions including the somatosensory cortex and visual
cortex in both FXS patients and the mouse model of FXS. Although recent studies
which employed state-of-the-art microscopy techniques suggested that only minute
differences were noticed between the WT and Fmr1−/y mice. In agreement with
previous findings, I found an increase of dendritic spine density in the visual cortex
in the Fmr1−/y mice, and spine morphology was also different between the two
genotypes. We found that the spine head diameter is significantly increased in the
CA1 area of the apical dendrites of the Fmr1−/y mice compared to WT controls.
Dendritic spine length is also significantly increased in the same region of the
Fmr1−/y mice. However, apical spine head size does not alter between the two
genotypes in the V1 region of the visual cortex, and spine length is significantly
decreased in the Fmr1−/y mice compared to WT animals in this region.
Lovastatin, a drug known as one of the 3-hydroxy-3-methyl-glutaryl-CoA
(HMG-CoA) reductase inhibitors, functions as a modulator of the mitogen-activated
protein kinases (MAPK) pathway through inhibiting Ras farnesylation, was used in
an attempt to rescue the dendritic spine abnormalities in the Fmr1−/y mice. Mice
lacking FMRP are susceptible to audiogenic seizure (AGS). Previous work has
shown that 48 hr of lovastatin treatment reduced the incidence of AGS in the Fmr1−/y
mice. However, chronic lovastatin treatment failed to rescue the spine density and
morphology abnormalities in the Fmr1−/y mice.
Mouse models are invaluable tools for modelling human diseases. However
inter-strain differences have often confounded results between laboratories. In my
final Chapter of this thesis, I compared two commonly used C57BL/6 substrains of
mice by recording their electrophysiological responses to visual stimuli in vivo. I
found a significant increase of high-frequency gamma power in adult C57BL/6JOla
mice, and this phenomenon was reduced during the critical period. My results
suggested that the C57BL/6JOla substrain has a significant stronger overall
inhibitory network activity in the visual cortex than the C57BL/6J substrain. This is
in good agreement with previous findings showing a lack of open-eye potentiation to
monocular deprivation in the C57BL/6JOla substrain, and highlights the need for
appropriate choice of mouse strain when studying neurodevelopmental models.
They also give valuable insights into the genetic mechanisms that permit experience-dependent
developmental plasticity.
In summary, these findings give us a better understanding of the fine structure
abnormalities of the Fmr1−/y mice, which in turn can benefit future discoveries of the
underlying mechanisms of neurodevelopmental disorders such as ID and ASDs
Distant-Time Location Prediction in Low-Sampling-Rate Trajectories
Abstract—With the growth of location-based services and social services, low-sampling-rate trajectories from check-in data or photos with geo-tag information becomes ubiquitous. In general, most detailed moving information in low-sampling-rate trajectories are lost. Prior works have elaborated on distant-time location prediction in high-sampling-rate trajectories. However, existing prediction models are pattern-based and thus not ap-plicable due to the sparsity of data points in low-sampling-rate trajectories. For example, it becomes difficult to derive trajectory patterns, let alone utilizing trajectory patterns for distant-time location prediction. In this paper, given a query time, the current location and time, we aim to predict the location of an object at the query time. To address the sparsity in low-sampling-rate trajectories, we develop a Reachability-based prediction model on Time-constrained Mobility Graph (abbreviated as RTMG) to predict locations for distant-time queries. Specifically, we design an adaptive temporal exploration approach to extract effective supporting trajectories that are temporally close to the query time. These data points are then represented as a Time-constrained user mobility Graph (refers to as TG). In light of TG, we further derive the reachability probabilities among locations in TG. Thus, a location with maximum reachability from the current location among all possible locations in sup-porting trajectories is considered as the prediction result. To efficiently process queries, we proposed an index structure SOIT to organize location records for on-line query processing. We conduct extensive experiments on real low-sampling-rate datasets and demonstrate the effectiveness and efficiency of RTMG. I
Chinese Herbal Medicine as an Adjunctive Therapy Ameliorated the Incidence of Chronic Hepatitis in Patients with Breast Cancer: A Nationwide Population-Based Cohort Study
We conducted a National Health Insurance Research Database-based Taiwanese nationwide population-based cohort study to evaluate whether Chinese herbal medicine (CHM) treatment decreased the incidence of chronic hepatitis in breast cancer patients receiving chemotherapy and/or radiotherapy. A total of 81171 patients were diagnosed with breast cancer within the defined study period. After randomly equal matching, data from 13856 patients were analyzed. Hazard ratios of incidence rate of chronic hepatitis were used to determine the influence and therapeutic potential of CHM in patients with breast cancer. The patients with breast cancer receiving CHM treatment exhibited a significantly decreased incidence rate of chronic hepatitis even across the stratification of age, CCI score, and treatments. The cumulative incidence of chronic hepatitis for a period of seven years after initial breast cancer diagnosis was also reduced in the patients receiving CHM treatment. The ten most commonly used single herbs and formulas were effective in protecting liver function in patients with breast cancer, where Hedyotis diffusa and Jia-Wei-Xiao-Yao-San were the most commonly used herbal agents. In conclusion, our study provided information that western medicine therapy combined with CHM as an adjuvant modality may have a significant impact on liver protection in patients with breast cancer
The Inhibitory Effect of Ellagic Acid on Cell Growth of Ovarian Carcinoma Cells
Ellagic acid (EA) is able to inhibit the growth of several cancer cells; however, its effect on human ovarian carcinoma cells has not yet been investigated. Ovarian carcinoma ES-2 and PA-1 cells were treated with EA (10~100 μM) and assessed for viability, cell cycle, apoptosis, anoikis, autophagy, and chemosensitivity to doxorubicin and their molecular mechanisms. EA inhibited cell proliferation in a dose- and time-dependent manner by arresting both cell lines at the G1 phase of the cell cycle, which were from elevating p53 and Cip1/p21 and decreasing cyclin D1 and E levels. EA also induced caspase-3-mediated apoptosis by increasing the Bax : Bcl-2 ratio and restored anoikis in both cell lines. The enhancement of apoptosis and/or inhibition of autophagy in these cells by EA assisted the chemotherapy efficacy. The results indicated that EA is a potential novel chemoprevention and treatment assistant agent for human ovarian carcinoma
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