Cognitive training can potentially prevent cognitive decline. However, the results of recent studies using semi-immersive virtual reality (VR)-assisted cognitive training are inconsistent.
We aimed ...to examine the hypothesis that cognitive training using fully immersive VR, which may facilitate visuospatial processes, could improve visuospatial functioning, comprehensive neuropsychological functioning, psychiatric symptoms, and functional connectivity in the visual brain network in predementia.
Participants over 60 years old with subjective cognitive decline or mild cognitive impairment from a memory clinic were randomly allocated to the VR (n=23) or the control (n=18) group. The VR group participants received multidomain and neuropsychologist-assisted cognitive training in a fully immersive VR environment twice a week for 1 month. The control group participants did not undergo any additional intervention except for their usual therapy such as pharmacotherapy. Participants of both groups were evaluated for cognitive function using face-to-face comprehensive neuropsychological tests, including the Rey-Osterrieth Complex Figure Test (RCFT) copy task; for psychiatric symptoms such as depression, apathy, affect, and quality of life; as well as resting-state functional magnetic resonance imaging (rsfMRI) at baseline and after training. Repeated-measures analysis of variance was used to compare the effect of cognitive training between groups. Seed-to-voxel-based analyses were used to identify the cognitive improvement-related functional connectivity in the visual network of the brain.
After VR cognitive training, significant improvement was found in the total score (F
=14.69, P=.001) and basic components score of the RCFT copy task (F
=9.27, P=.005) compared with those of the control group. The VR group also showed improvements, albeit not significant, in naming ability (F
=3.55, P=.07), verbal memory delayed recall (F
=3.03, P=.09), and phonemic fluency (F
=3.08, P=.09). Improvements in psychiatric symptoms such as apathy (F
=7.02, P=.01), affect (F
=14.40, P=.001 for positive affect; F
=4.23, P=.047 for negative affect), and quality of life (F
=4.49, P=.04) were found in the VR group compared to the control group. Improvement in the RCFT copy task was associated with a frontal-occipital functional connectivity increase revealed by rsfMRI in the VR group compared to the control group.
Fully immersive VR cognitive training had positive effects on the visuospatial function, apathy, affect, quality of life, and increased frontal-occipital functional connectivity in older people in a predementia state. Future trials using VR cognitive training with larger sample sizes and more sophisticated designs over a longer duration may reveal greater improvements in cognition, psychiatric symptoms, and brain functional connectivity.
Clinical Research Information Service KCT0005243; https://tinyurl.com/2a4kfasa.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
We inaugurate a program of “mass production” of microlensing planets discovered in 2021 KMTNet data, with the aim of laying the basis for future statistical studies. While we ultimately plan ...to quickly publish all 2021 planets meeting some minimal criteria, the current sample of four was chosen simply on the basis of having low initial estimates of the planet–host mass ratio,
q
. It is therefore notable that two members of this sample suffer from a degeneracy in the normalized source radius
ρ
that arises from different morphologies of closely spaced caustics. All four planets (KMT-2021-BLG-1391, KMT-2021-BLG-1253, KMT-2021-BLG-1372, KMT-2021-BLG-0748) have well-characterized mass ratios,
q
, and therefore are suitable for mass-ratio frequency studies. Both of the
ρ
degeneracies can be resolved by future adaptive optics (AO) observations on 30 m class telescopes. We provide general guidance for such AO observations for all events in anticipation of the prospect that they will revolutionize the field of microlensing planets.
Aims.
We reexamine high-magnification microlensing events in the previous data collected by the KMTNet survey with the aim of finding planetary signals that were not noticed before. In this work, we ...report the planetary system KMT-2018-BLG-1988L, which was found from this investigation.
Methods.
The planetary signal appears as a deviation with ≲0.2 mag from a single-lens light curve and lasted for about 6 h. The deviation exhibits a pattern of a dip surrounded by weak bumps on both sides of the dip. The analysis of the lensing light curve indicates that the signal is produced by a low-mass-ratio (
q
~ 4 × 10
−5
) planetary companion located near the Einstein ring of the host star.
Results.
The mass of the planet, M
planet
= 6.8
−3.5
+4.7
M
⊕
and 5.6
−2.8
+3.8
M
⊕
for the two possible solutions, estimated from the Bayesian analysis indicates that the planet is in the regime of a super-Earth. The host of the planet is a disk star with a mass of M
host
= 0.47
−0.25
+0.33
M
⊙
and a distance of D
L
= 4.2
−.14
+1.8
kpc. KMT-2018-BLG-1988Lb is the 18th known microlensing planet with a mass below the upper limit of a super-Earth. The fact that 15 out of the 18 known microlensing planets with masses ≲10
M
⊕
were detected in the 5 yr following the full operation of the KMTNet survey indicates that the KMTNet database is an important reservoir of very low-mass planets.
Abstract
We continue our program of publishing all planets (and possible planets) found by eye in 2021 Korea Microlensing Telescope Network (KMTNet) online data. We present four planets ...(KMT-2021-BLG-0712Lb, KMT-2021-BLG-0909Lb, KMT-2021-BLG-2478Lb, and KMT-2021-BLG-1105Lb), with planet-to-host mass ratios in the range
−
3.3
≲
log
q
≲
−
2.2
. This brings the total of secure, by-eye, 2021 KMTNet planets to 16, including 8 in this series. The by-eye sample is an important check of the completeness of semiautomated detections, which are the basis for statistical analyses. One of the planets, KMT-2021-BLG-1105Lb, is blended with a relatively bright (
I
,
V
) ∼ (18.9, 21.6) star that may be the host. This could be verified immediately by high-resolution imaging. If so, the host is an early G dwarf, and the planet could be characterized by radial velocity observations on 30 m class telescopes.
Abstract
We analyze the very short Einstein timescale (
t
E
≃ 7 hr) event KMT-2019-BLG-2073. Making use of the pronounced finite-source effects generated by the clump giant source, we measure the ...Einstein radius
θ
E
≃ 4.8
μ
as and so infer a mass
M
=
59
M
⊕
(
π
rel
/
16
μ
as
)
−
1
, where
π
rel
is the lens-source relative parallax. We find no significant evidence for a host of this planetary-mass object, though one could be present at sufficiently wide separation. If so, it would be detectable after about 10 yr. This is the fourth isolated microlens with a measured Einstein radius
θ
E
< 10
μ
as, which we argue is a useful threshold for a “likely free-floating planet (FFP)” candidate. We outline a new approach to constructing a homogeneous sample of giant-star finite-source/point-lens (FSPL) events, within which the subsample of FFP candidates can be statistically analyzed. We illustrate this approach using 2019 KMTNet data and show that there appears to be a large
θ
E
gap between the two FFP candidates and the 11 other FSPL events. We argue that such sharp features are more identifiable in a sample selected on
θ
E
compared to the traditional approach of identifying candidates based on short
t
E
.
OGLE-2014-BLG-0962 (OB140962) is a stellar binary microlensing event that was well covered by observations from the Spitzer satellite as well as ground-based surveys. Modeling yields a unique ...physical solution: a mid-M+M-dwarf binary with Mprim = 0.20 0.01 M☉ and Msec = 0.16 0.01 M☉, with projected separation of 2.0 0.3 au. The lens is only DLS = 0.41 0.06 kpc in front of the source, making OB140962 a bulge lens and the most distant Spitzer binary lens to date. In contrast, because the Einstein radius (θE = 0.143 0.007 mas) is unusually small, a standard Bayesian analysis, conducted in the absence of parallax information, would predict a brown dwarf binary. We compare the results of Bayesian analysis using two commonly used Galactic model priors to the measured values for a set of Spitzer lenses. We find all models tested predict lens properties consistent with the Spitzer data. Furthermore, we illustrate the methodology for probing the Galactic distribution of planets by comparing the cumulative distance distribution of the Spitzer two-body lenses to that of the Spitzer single lenses.
MACHO-97-BLG-41 is a gravitational microlensing event produced by a lens composed of multiple masses detected by the first-generation lensing experiment. For the event, there exist two different ...interpretations of the lens from independent analyses based on two different data sets: one interpreted the event as produced by a circumbinary planetary system while the other explained the light curve with only a binary system by introducing orbital motion of the lens. According to the former interpretation, the lens would not only be the first planet detected via microlensing but also the first circumbinary planet ever detected. To resolve the issue using state-of-the-art analysis methods, we reanalyze the event based on the combined data used separately by the previous analyses. By considering various higher-order effects, we find that the orbiting binary-lens model provides a better fit than the circumbinary planet model with Delta chi super(2) ~ 166. The result signifies the importance of even and dense coverage of lensing light curves in the interpretation of events.
Abstract
We complete the analysis of all 2018 sub-prime-field microlensing planets identified by the KMTNet AnomalyFinder. Among the 9 previously unpublished events with clear planetary solutions, 6 ...are clearly planetary (OGLE-2018-BLG-0298, KMT-2018-BLG-0087, KMT-2018-BLG-0247, KMT-2018-BLG-0030, OGLE-2018-BLG-1119, and KMT-2018-BLG-2602), while the remaining 3 are ambiguous in nature. The above ordering of these events is made to facilitate grouping of their Bayesian estimates: the first two are lower-mass gas giants while the last four are Jovian-class planets; the first three most likely lie in the bulge, the last in the disk, and the remaining two are equally likely to be in either population. More specifically, these six planets have host masses
M
host
=
(
0.69
−
0.30
+
0.34
,
0.10
−
0.05
+
0.14
,
0.29
−
0.14
+
0.28
,
0.51
−
0.31
+
0.43
,
0.48
−
0.28
+
0.35
,
0.66
−
0.36
+
0.42
)
M
⊙
, planet masses
M
planet
=
(
0.14
−
0.06
+
0.07
,
0.23
−
0.12
+
0.32
,
2.11
−
1.04
+
2.09
,
1.45
−
0.88
+
1.23
,
0.91
−
0.52
+
0.66
,
1.15
−
0.63
+
0.73
)
M
Jup
, and distances
D
L
=
(
6.54
−
1.23
+
0.95
,
7.02
−
1.15
+
1.03
,
6.76
−
1.24
+
0.99
,
6.48
−
1.96
+
1.28
,
5.76
−
2.48
+
1.43
,
4.31
−
1.84
+
1.97
)
kpc
. In addition, there are 8 previously published sub-prime-field planets that were selected by the AnomalyFinder algorithm. Together with a companion paper on 2018 prime-field planets, this work lays the basis for comprehensive statistical studies. We carry out two such studies, one on caustic topologies and the other on the role of Gaia data. From the first, as expected, half (17/33) of the 2018 planets likely to enter the mass-ratio analysis have non-caustic-crossing anomalies. However, only 1 of the 5 noncaustic anomalies with planet-host mass ratio
q
< 10
−3
was discovered by eye (compared to 7 of the 12 with
q
> 10
−3
), showing the importance of the semiautomated AnomalyFinder search. From the second, we find that Gaia has played a major role in the interpretation of 16% of the sample and a supplementary role in 6%.
ABSTRACT Recently, the discovery of a Venus-mass planet orbiting a brown-dwarf host in a binary system was reported from the analysis of the microlensing event OGLE-2013-BLG-0723. We reanalyze the ...event considering the possibility of other interpretations. From this, we find a new solution where the lens is composed of two bodies, in contrast to the three-body solution of the previous analysis. The new solution better explains the observed light curve than the previous solution with Δχ2 ∼ 202, suggesting that the new solution is a correct model for the event. From the estimation of the physical parameters based on the new interpretation, we find that the lens system is composed of two low-mass stars with ∼0.2 M and ∼0.1 M and located at a distance of ∼3 kpc. The fact that the physical parameters correspond to those of the most common lens population located at a distance with a large lensing probability further supports the likelihood of the new interpretation. Considering that two dramatically different solutions can approximately explain the observed light curve, the event suggests the need for carefully testing all possible lens-system geometries.
Abstract
We analyze the microlensing event OGLE-2019-BLG-0304, whose light curve exhibits two distinctive features: a deviation in the peak region and a second bump appearing ∼61 days after the main ...peak. Although a binary-lens model can explain the overall features, it leaves subtle but noticeable residuals in the peak region. We find that the residuals can be explained by the presence of either a planetary companion located close to the primary of the binary lens (3L1S model) or an additional close companion to the source (2L2S model). Although the 3L1S model is favored over the 2L2S model, with Δ
χ
2
∼ 8, securely resolving the degeneracy between the two models is difficult with the currently available photometric data. According to the 3L1S interpretation, the lens is a planetary system, in which a planet with a mass
0.51
−
0.23
+
0.51
M
J
is in an S-type orbit around a binary composed of stars with masses
0.27
−
0.12
+
0.27
M
⊙
and
0.10
−
0.04
+
0.10
M
⊙
. According to the 2L2S interpretation, however, the source is composed of G- and K-type giant stars and the lens is composed of a low-mass M dwarf and a brown dwarf with masses
0.12
−
0.05
+
0.12
M
⊙
and
0.045
−
.019
+
0.045
M
⊙
, respectively. The event illustrates the need for thorough model testing in the interpretation of lensing events with complex features in light curves.
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