172 research outputs found
A Born-type approximation method for bioluminescence tomography
In this paper, we present a Born-type approximation method for bioluminescence tomography (BLT), which is to reconstruct an internal bioluminescent source from the measured bioluminescent signal on the external surface of a small animal. Based on the diffusion approximation for the photon propagation in biological tissue, this BLT method utilizes the Green function to establish a linear relationship between the measured bioluminescent signal and the internal bioluminescent source distribution. The Green function can be modified to describe a heterogeneous medium with an arbitrary boundary using the Born approximation. The BLT reconstruction is formulated in a linear least-squares optimization framework with simple bounds constraint. The performance of this method is evaluated in numerical simulation and phantom experiments
Non-Fermi-liquid behavior in nearly ferromagnetic metallic SrIrO3 single crystals
We report transport and thermodynamic properties of single-crystal SrIrO3 as
a function of temperature T and applied magnetic field H. We find that SrIrO3
is a non-Fermi-liquid metal near a ferromagnetic instability, as characterized
by the following properties: (1) small ordered moment but no evidence for
long-range order down to 1.7 K; (2) strongly enhanced magnetic susceptibility
that diverges as T or T1/2 at low temperatures, depending on the applied field;
(3) heat capacity C(T,H) ~ -Tlog T that is readily amplified by low applied
fields; (4) a strikingly large Wilson ratio at T< 4K; and (5) a T3/2-dependence
of electrical resistivity over the range 1.7 < T < 120 K. A phase diagram based
on the data implies SrIrO3 is a rare example of a stoichiometric oxide compound
that exhibits non-Fermi-liquid behavior near a quantum critical point (T = 0
and H = 0.23 T)
Correlation of 25-Hydroxycholecalciferol and Glycaemic Status in Recent Onset Type 2 Diabetes Mellitus
Introduction: Type 2 Diabetes Mellitus (T2DM) is a non communicable disease caused by increased insulin resistance and beta cells dysfunction. Recently vitamin D has sparked wide spread interest in pathogenesis of diabetes by playing a role in insulin resistance. As a major regulator of homeostasis of calcium, vitamin D directly and/or indirectly improves insulin exocytosis and glucose tolerance.
Aim: To estimate the serum 25 hydroxy cholecalciferol level and also to correlate with fasting, two hour postprandial blood glucose and Glycated Haemoglobin (HbA1c) values in recent onset T2DM patients.
Materials and Methods: This cross-sectional study was conducted at Government Kilpauk Medical College, Tamil Nadu, India from November 2017-April 2018. One hundred and thirty nine recently diagnosed T2DM patients aged between 30-60 years of both sex, who were on oral hypoglycemic drugs for less than three months duration were included in the study. The patients were grouped into three groups according to their vitamin D levels, Group 1 Vitamin D deficient- 52 patients (ā¤20 ng/mL), Group 2- Insufficient Vitamin D -33 patients (>20-30 ng/mL), Group 3- Vitamin D sufficient-54 patients (>30 ng/mL). Fasting and 2 hour postprandial glucose, 25 hydroxy cholecalciferol and HbA1c were estimated. Statistical analysis was performed using analysis of variance (ANOVA) and Pearsonās correlation.
Results: Out of 139 participants, 64 were males and 75 were females. The mean age of the study population was 50.64Ā±5.343 years. The mean fasting blood glucose values among the three groups were 168.13, 129.61, and 125.33 mg/dL respectively. The mean two hour postprandial blood glucose values among the three groups were 269.44, 212.45, and 194.11 mg/dL respectively. The mean HbA1c among the three groups were 7.481Ā±1.16, 6.027Ā±0.31, and 5.86Ā±0.19, respectively. Decreased 25 hydroxy cholecalciferol level in patients of T2DM showed a statistically significant inverse correlation with fasting and two hour postprandial blood glucose and HbA1c with p-value <0.001.
Conclusion: The study suggested that hypovitaminosis D was prevalent in T2DM. The study showed that decreased vitamin D level in T2DM patients was associated with increased fasting, postprandial blood sugar, and HbA1c. So, vitamin D screening in diabetics and supplementation can improve the glycemic status
A Born-type approximation method for bioluminescence tomography
In this paper, we present a Born-type approximation method for bioluminescence tomography (BLT), which is to reconstruct an internal bioluminescent source from the measured bioluminescent signal on the external surface of a small animal. Based on the diffusion approximation for the photon propagation in biological tissue, this BLT method utilizes the Green function to establish a linear relationship between the measured bioluminescent signal and the internal bioluminescent source distribution. The Green function can be modified to describe a heterogeneous medium with an arbitrary boundary using the Born approximation. The BLT reconstruction is formulated in a linear least-squares optimization framework with simple bounds constraint. The performance of this method is evaluated in numerical simulation and phantom experiments
Prevention of: self harm in British South Asian women: study protocol of an exploratory RCT of culturally adapted manual assisted Problem Solving Training (C- MAP)
<p>Abstract</p> <p>Background</p> <p>Suicide is a major public health problem worldwide. In the UK suicide is the second most common cause of death in people aged 15-24 years. Self harm is one of the commonest reasons for medical admission in the UK. In the year following a suicide attempt the risk of a repeat attempt or death by suicide may be up to 100 times greater than in people who have never attempted suicide.</p> <p>Research evidence shows increased risk of suicide and attempted suicide among British South Asian women. There are concerns about the current service provision and its appropriateness for this community due to the low numbers that get involved with the services. Both problem solving and interpersonal forms of psychotherapy are beneficial in the treatment of patients who self harm and could potentially be helpful in this ethnic group.</p> <p>The paper describes the trial protocol of adapting and evaluating a culturally appropriate psychological treatment for the adult British South Asian women who self harm.</p> <p>Methods</p> <p>We plan to test a culturally adapted Problem Solving Therapy (C- MAP) in British South Asian women who self harm. Eight sessions of problem solving each lasting approximately 50 minutes will be delivered over 3 months. The intervention will be assessed using a prospective rater blind randomized controlled design comparing with treatment as usual (TAU). Outcome assessments will be carried out at 3 and 6 months. A sub group of the participants will be invited for qualitative interviews.</p> <p>Discussion</p> <p>This study will test the feasibility and acceptability of the C- MAP in British South Asian women. We will be informed on whether a culturally adapted brief psychological intervention compared with treatment as usual for self-harm results in decreased hopelessness and suicidal ideation. This will also enable us to collect necessary information on recruitment, effect size, the optimal delivery method and acceptability of the intervention in preparation for a definitive RCT using repetition of self harm and cost effectiveness as primary outcome measures.</p> <p>Trial Registration</p> <p>Current Controlled Trials 08/H1013/6</p
Colossal Magnetoresistance by Avoiding a Ferromagnetic State in the Mott System Ca3Ru2O7
Transport and magnetic studies of Ca3Ru2O7 for temperatures ranging from 0.4
K to 56 K and magnetic fields, B, up to 45 T leads to strikingly different
behavior when the field is applied along the different crystal axes. A
ferromagnetic (FM) state with full spin polarization is achieved for B||a-axis,
but colossal magnetoresistance is realized only for B||b-axis. For B||c-axis,
Shubnikov-de Haas oscillations are observed and followed by a less resistive
state than for B||a. Hence, in contrast to standard colossal magnetoresistive
materials, the FM phase is the least favorable for electron hopping. These
properties together with highly unusual spin-charge-lattice coupling near the
Mott transition (48 K) are driven by the orbital degrees of freedom.Comment: 15 pages including 3 figure
High-temperature weak ferromagnetism on the verge of a metallic state: Impact of dilute Sr-doping on BaIrO3
The 5d-electron based BaIrO3 is a nonmetallic weak ferromagnet with a Curie
temperature at Tc=175 K. Its largely extended orbitals generate strong
electron-lattice coupling, and magnetism and electronic structure are thus
critically linked to the lattice degree of freedom. Here we report results of
our transport and magnetic study on slightly Sr doped BaIrO3. It is found that
dilute Sr-doping drastically suppresses Tc, and instantaneously leads to a
nonmetal-metal transition at high temperatures. All results highlight the
instability of the ground state and the subtle relation between magnetic
ordering and electron mobility. It is clear that BaIrO3 along with very few
other systems represents a class of materials where the magnetic and transport
properties can effectively be tuned by slight alterations in lattice
parameters
In vivo tomographic imaging based on bioluminescence
The most important task for bioluminescence imaging is to identify the emission source from the captured bioluminescent signal on the surface of a small tested animal. Quantitative information on the source location, geometry and intensity serves for in-vivo monitoring of infectious diseases, tumor growth, metastases in the small animal. In this paper, we present a point-spread function-based method for reconstructing the internal bioluminescent source from the surface light output flux signal. The method is evaluated for sensing the internal emission sources in nylon phantoms and within a live mouse. The surface bioluminescent signal is taken with a highly sensitive CCD camera. The results show the feasibility and efficiency of the proposed point-spread function-based method
Partial antiferromagnetism in spin-chain Sr5Rh4O12, Ca5Ir3O12 and Ca4IrO6 single crystals
We report a structural, thermodynamic and transport study of the newly
synthesized Sr5Rh4O12, Ca5Ir3O12 and Ca4IrO6 single crystals. These
quasi-one-dimensional insulators consist of a triangular lattice of spin chains
running along the c-axis, and are commonly characterized by a partial
antiferromagnetic (AFM) order, a small entropy removal associated with the
phase transitions and a sizable low-temperature specific heat linearly
proportional to temperature. Sr5Rh4O12 is defined by an AFM order below 23 K
with strong evidence for an Ising character and two step-like transitions in
isothermal magnetization leading to a ferrimagnetic state at 2.4 T and a
ferromagnetic state at 4.8 T, respectively. Ca5Ir3O12 and Ca4IrO6 are also
antiferromagnetically ordered below 7.8 K and 12 K, respectively, and show an
unusually large ratio of the Curie-Weiss temperature to the Neel temperature.
In particular, Ca5Ir3O12, which includes both Ir4+ and Ir5+ ions, reveals that
only S=1/2 spins of the Ir4+ ions are involved in the magnetic ordering whereas
S=3/2 spins of the Ir5+ ions remain disordered. All results suggest the
presence of the geometrical frustration that causes incomplete long-range AFM
order in these quasi-one-dimensional compounds
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