People with chronic low back pain (LBP) exhibit changes in postural control. Stereotypical muscle activations resulting from external perturbations include anticipatory (APAs) and compensatory (CPAs) ...postural adjustments. The aim and objective of this study was to determine differences in postural control strategies (peak amplitude, APAs and CPAs) between symptomatic and asymptomatic adults with and without Lumbar Disc Degeneration (LDD) using surface electromyography during forward postural perturbation. Ninety-seven subjects participated in the study (mean age 50 years (SD 12)). 3T MRI was used to acquire T2 weighted images (L1-S1). LDD was determined using Pfirrmann grading. A bespoke translational platform was designed to deliver horizontal perturbations in sagittal and frontal planes. Electromyographic activity was analysed bilaterally from 8 trunk and lower limb muscles during four established APA and CPA epochs. A Kruskal-Wallis H test with Bonferroni correction for multiple comparisons was conducted. Four groups were identified: no LDD no pain (n = 19), LDD no pain (n = 38), LDD pain (n = 35) and no LDD pain (n = 5). There were no significant differences in age or gender between groups. The most significant difference between groups was observed during forward perturbation. In the APA and CPA phases of predictable forward perturbation there were significant differences ankle strategy between groups (p = 0.007-0.008); lateral gastrocnemius and tibialis anterior activity was higher in the LDD pain than the LDD no pain group. There were no significant differences in the unpredictable condition (p>0.05). These findings were different from the remaining groups, where significant differences in hip strategy were observed during both perturbation conditions (p = 0.004-0.006). Symptomatic LDD patients exhibit different electromyographic strategies to asymptomatic LDD controls. Future LBP electromyographic research should benefit from considering assessment of both lower limbs in addition to the spine. This approach could prevent underestimation of postural control deficits and guide targeted rehabilitation.
A hyperlink is a finite set of non-intersecting simple closed curves in
R
4
≡
R
×
R
3
, and each curve is either a matter or geometric loop. We consider an equivalence class of such hyperlinks, up to ...time-like isotopy, preserving time-ordering. Using an equivalence class and after coloring each matter component loop with an irreducible representation of
s
u
(
2
)
×
su
(
2
)
, we can define its Wilson loop observable using an Einstein–Hilbert action, which is now thought of as a functional acting on the set containing equivalence classes of hyperlink. Construct a vector space using these functionals, which we now term as quantum states. To make it into a Hilbert space, we need to define a counting probability measure on the space containing equivalence classes of hyperlinks. In our previous work, we defined area, volume and curvature operators, corresponding to given geometric objects like surface and a compact solid spatial region. These operators act on the quantum states and, by deliberate construction of the Hilbert space, are self-adjoint and possibly unbounded operators. Using these operators and Einstein’s field equations, we can proceed to construct a quantized stress operator and also a Hamiltonian constraint operator for the quantum system. We will also use the area operator to derive the Bekenstein entropy of a black hole. In the concluding section, we will explain how loop quantum gravity predicts the existence of gravitons, implies causality and locality in quantum gravity and formulates the principle of equivalence mathematically in its framework.
Maternally deposited mRNAs direct early development before the initiation of zygotic transcription during mid-blastula transition (MBT). To study mechanisms regulating this developmental event in ...zebrafish, we applied mRNA deep sequencing technology and generated comprehensive information and valuable resources on transcriptome dynamics during early embryonic (egg to early gastrulation) stages. Genome-wide transcriptome analysis documented at least 8000 maternal genes and identified the earliest cohort of zygotic transcripts. We determined expression levels of maternal and zygotic transcripts with the highest resolution possible using mRNA-seq and clustered them based on their expression pattern. We unravel delayed polyadenylation in a large cohort of maternal transcripts prior to the MBT for the first time in zebrafish. Blocking polyadenylation of these transcripts confirms their role in regulating development from the MBT onward. Our study also identified a large number of novel transcribed regions in annotated and unannotated regions of the genome, which will facilitate reannotation of the zebrafish genome. We also identified splice variants with an estimated frequency of 50%-60%. Taken together, our data constitute a useful genomic information and valuable transcriptome resource for gene discovery and for understanding the mechanisms of early embryogenesis in zebrafish.
A hyperlink is a finite set of non-intersecting simple closed curves in
R
×
R
3
. Let
R
be a compact set inside
R
3
. The dynamical variables in General Relativity are the vierbein
e
and a
su
(
2
)
×
...su
(
2
)
-valued connection
ω
. Together with Minkowski metric,
e
will define a metric
g
on the manifold. Denote
V
R
(
e
)
as the volume of
R
, for a given choice of
e
. The Einstein–Hilbert action
S
(
e
,
ω
)
is defined on
e
and
ω
. We will quantize the volume of
R
by integrating
V
R
(
e
)
against a holonomy operator of a hyperlink
L
, disjoint from
R
, and the exponential of the Einstein–Hilbert action, over the space of vierbein
e
and
su
(
2
)
×
su
(
2
)
-valued connection
ω
. Using our earlier work done on Chern–Simons path integrals in
R
3
, we will write this infinite-dimensional path integral as the limit of a sequence of Chern–Simons integrals. Our main result shows that the volume operator can be computed by counting the number of nodes on the projected hyperlink in
R
3
, which lie inside the interior of
R
. By assigning an irreducible representation of
su
(
2
)
×
su
(
2
)
to each component of
L
, the volume operator gives the total kinetic energy, which comes from translational and angular momentum.
Ultrasound practice is a longstanding tradition for radiology departments, being part of the family of imaging techniques. Ultrasound is widely practiced by non-radiologists but becoming less popular ...within radiology. The position of ultrasound in radiology is reviewed, and a possible long-term solution to manage radiologist expectations is proposed. An international group of experts in the practice of ultrasound was invited to describe the current organisation of ultrasound within the radiology departments in their own countries and comment on the interaction with non-radiologists and training arrangements. Issues related to regulation, non-medical practitioners, and training principles are detailed. A consensus view was sought from the experts regarding the position of ultrasound within radiology, with the vision of the best scenario for the continuing dominance of radiologists practising ultrasound. Comments were collated from nine different countries. Variable levels of training, practice, and interaction with non-radiologist were reported, with some countries relying on non-physician input to manage the service. All experts recognised there was a diminished desire to practice ultrasound by radiologists. Models varied from practising solely ultrasound and no other imaging techniques to radiology departments being central to the practice of ultrasound by radiologists and non-radiologist, housed within radiology. The consensus view was that the model favoured in select hospitals in Germany would be the most likely setup for ultrasound radiologist to develop and maintain practice. The vision for 20 years hence is for a central ultrasound section within radiology, headed by a trained expert radiologist, with non-radiologist using the facilities.
Critical relevance statement
The future of ultrasound within the radiology department should encompass all ultrasound users, with radiologists expert in ultrasound, managing the ultrasound section within the radiology department. The current radiology trainees must learn of the importance of ultrasound as a component of the ‘holistic’ imaging of the patient.
Key points:
1. Ultrasound imaging within radiology departments precedes the introduction of CT and MR imaging and was first used over 50 years ago.
2. Non-radiology practitioners deploy ultrasound examinations to either ‘problem solve’ or perform a comprehensive ultrasound examination; radiologists provide comprehensive examinations or use ultrasound to direct interventional procedures.
3. Radiology does not ‘own’ ultrasound, but radiologists are best placed to offer a comprehensive patient-focused imaging assessment.
4. A vision of the future of ultrasound within the radiology department is encompassing all ultrasound users under radiologists who are experts in ultrasound, positioned within the radiology department.
5. The current radiology trainee must be aware of the importance of ultrasound as a component of the ‘holistic’ imaging of the patient.
Invariants in Quantum Geometry Lim, Adrian P.C.
Reports on mathematical physics,
February 2021, 2021-02-00, Volume:
87, Issue:
1
Journal Article
Peer reviewed
In quantum geometry, we consider a set of loops, a compact orientable surface and a solid compact spatial region, all inside ℝ × ℝ3 = ℝ4, which forms a triple. We want to define an ambient isotopic ...equivalence relation on such triples, so that we can obtain equivalence invariants. These invariants describe how these submanifolds are causally related to or ‘linked’ with each other, and they are closely associated with the linking number between links in ℝ3. Because we distinguish the time-axis from spatial subspace in ℝ4, we see that these equivalence relations will also imply causality.
Most ultrasound-based methods for assessing liver fibrosis still need further validation with liver biopsy used as gold standard to assess their accuracy.
To assess accuracy of three shear wave ...elastography (SWE) methods: 1) Philips Elast Point Quantification (ElastPQTM), 2) Siemens Virtual TouchTM Quantification (VTQ) acoustic radiation force impulse (ARFI), and 3) transient elastography (TE) measured by Echosens FibroscanTM.
160 patients underwent liver stiffness measurements (LSM) with three SWE methods immediately prior to liver biopsy.
The number of LSM required for reliable studies could be reduced to 6 for ElastPQ and to 7 for VTQ from standard recommendations of 10. Significant fibrosis and interquartile range/median (IQR/M)> 30 were independent predictors for lower reliability for detection of liver fibrosis. Ordinal logistic regression corrected for age showed that there was a significant interaction between steatosis (p = 0.008) and lobular inflammation (p = 0.04) and VTQ (ARFI) and between lobular inflammation and TE (p = 0.006).
We showed variations in SWE measurements using different ARFI technologies. TE and ElastPQ achieved good diagnostic performance, whereas VTQ showed lower diagnostic accuracy. The number of measurements required for reliable studies can be reduced to 6 for ElastPQ and to 7 for VTQ, which have important clinical implications.
Lumbar disc degeneration (LDD) is a condition associated with recurrent low back pain (LBP). Knowledge regarding effective management is limited. As a step towards the identification of risk, ...prognostic or potentially modifiable factors in LDD patients, the aim of this study was to explore the hypothesis that intrinsic lumbar spine shape is associated with LDD and clinical outcomes in symptomatic adults.
3 T MRI was used to acquire T2-weighted sagittal images (L1-S1) from 70 healthy controls and LDD patients (mean age 49 years, SD 11, range 31-71 years). Statistical Shape Modelling (SSM) was used to describe lumbar spine shape. SSM identified variations in lumbar shape as 'modes' of variation and quantified deviation from the mean. Intrinsic shape differences were determined between LDD groups using analysis of variance with post-hoc comparisons. The relationship between intrinsic shape and self-reported function, mental health and quality of life were also examined.
The first 7 modes of variation explained 91% of variance in lumbar shape. Higher LDD sum scores correlated with a larger lumbar lordosis (Mode 1 (55% variance), P = 0.02), even lumbar curve distribution (Mode 2 (12% variance), P = 0.05), larger anterior-posterior (A-P) vertebral diameter (Mode 3 (10% variance), P = 0.007) and smaller L4-S1 disc spaces (Mode 7 (2% variance), P ≤ 0.001). In the presence of recurrent LBP, LDD was associated with a larger A-P vertebral diameter (Mode 3) and a more even lumbar curvature with smaller L5/S1 disc spaces (Mode 4), which was significantly associated with patient quality of life (P = 0.002-0.04, r
= 0.43-0.61)).
This exploratory study provides new evidence that intrinsic shape phenotypes are associated with LDD and quality of life in patients. Longitudinal studies are required to establish the potential role of these risk or prognostic shape phenotypes.
•Lumbar Disc Degeneration (LDD) is commonly associated with low back pain.•Symptomatic LDD patients exhibit different postural strategies to LDD controls.•This strategic difference is observed within ...the trunk and lower limbs.•Effective care may benefit from evaluating and targeting these differences.
Lumbar Disc Degeneration (LDD) is associated with recurrent low back pain (LBP) (symptomatic). However, in some instances of LDD, people do not experience LBP (asymptomatic).
As a step towards understanding why some people with LDD experience LBP and others do not, the primary aim of this study was to examine differences in anticipatory (APA) and compensatory postural adjustments (CPA), between symptomatic LDD patients (LDD pain) and asymptomatic LDD controls (LDD no pain) during postural perturbation. The secondary aim was to determine simultaneous differences in mental health, disability and quality of life status.
3 T MRI was used to acquire T2 weighted images (L1-S1) from LDD no pain (n = 34) and LDD pain groups (n = 34). In this observational study, responses to predicted and unpredicted forward perturbations were examined using three dimensional motion capture. A Mann Whitney U test was conducted to examine group differences in sagittal spine and lower limb kinematics (integrated angular displacements during four established APA and CPA time intervals), anxiety, depression, disability and quality of life.
The LDD pain group exhibited lower hip and knee displacements (p = 0.049−0.040) than the LDD no pain group during predicted and unpredicted perturbation. The LDD pain group also exhibited higher compensatory lumbar displacement than the LDD no pain group (p = 0.040−0.005) in the predicted condition but there was no difference observed in the unpredicted condition. The LDD pain group experienced higher levels of depression, anxiety and disability (p < 0.0001) and lower quality of life (p = 0.0001) than LDD controls.
Symptomatic LDD patients are different from LDD controls; they exhibit different kinematic strategies, levels of disability, anxiety, depression and quality of life. Effective care may benefit from evaluating and targeting these differences.
UIO Editorial Lim, Adrian
Ultrasound international open,
10/2018, Volume:
4, Issue:
4
Journal Article
Peer reviewed
Open access
It is with great pleasure again that I introduce the December 2018 issue of Ultrasound International Open.
This issue has a focus on Neck ultrasound where the first article highlights the value of ...careful sonographic observations of thyroid nodules which will improve diagnostic accuracy and help select suspicious nodules for histological sampling. The article also provides many examples and highlights some helpful tips.
PDF
