The four square theorem

2003 ◽  
pp. 138-157
Author(s):  
John Stillwell
Keyword(s):  
Four Square

scholarly journals Factors associated with dynamic balance in people with Persistent Postural Perceptual Dizziness (PPPD): a cross-sectional study using a virtual-reality Four Square Step Test

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Moshe M. H. Aharoni ◽  
Anat V. Lubetzky ◽  
Liraz Arie ◽  
Tal Krasovsky
Keyword(s):  
Virtual Reality ◽  
Trait Anxiety ◽  
Dynamic Balance ◽  
Step Test ◽  
Simulator Sickness ◽  
Balance Confidence ◽  
Task Duration ◽  
Head Kinematics ◽  
Perceived Disability ◽  
Four Square

Abstract Background Persistent postural-perceptual dizziness (PPPD) is a condition characterized by chronic subjective dizziness and exacerbated by visual stimuli or upright movement. Typical balance tests do not replicate the environments known to increase symptoms in people with PPPD—crowded places with moving objects. Using a virtual reality system, we quantified dynamic balance in people with PPPD and healthy controls in diverse visual conditions. Methods Twenty-two individuals with PPPD and 29 controls performed a square-shaped fast walking task (Four-Square Step Test Virtual Reality—FSST-VR) using a head-mounted-display (HTC Vive) under 3 visual conditions (empty train platform; people moving; people and trains moving). Head kinematics was used to measure task duration, movement smoothness and anterior–posterior (AP) and medio-lateral (ML) ranges of movement (ROM). Heart rate (HR) was monitored using a chest-band. Participants also completed a functional mobility test (Timed-Up-and-Go; TUG) and questionnaires measuring anxiety (State-Trait Anxiety Inventory; STAI), balance confidence (Activities-Specific Balance Confidence; ABC), perceived disability (Dizziness Handicap Inventory) and simulator sickness (Simulator Sickness Questionnaire). Main effects of visual load and group and associations between performance, functional and self-reported outcomes were examined. Results State anxiety and simulator sickness did not increase following testing. AP-ROM and HR increased with high visual load in both groups (p < 0.05). There were no significant between-group differences in head kinematics. In the high visual load conditions, high trait anxiety and longer TUG duration were moderately associated with reduced AP and ML-ROM in the PPPD group and low ABC and  high perceived disability were associated with reduced AP-ROM (|r| =  0.47 to 0.53; p < 0.05). In contrast, in controls high STAI-trait, low ABC and longer TUG duration were associated with increased AP-ROM (|r| = 0.38 to 0.46; p < 0.05) and longer TUG duration was associated with increased ML-ROM (r = 0.53, p < 0.01). Conclusions FSST-VR may shed light on movement strategies in PPPD beyond task duration. While no main effect of group was observed, the distinct associations with self-reported and functional outcomes, identified using spatial head kinematics, suggest that some people with PPPD reduce head degrees of freedom when performing a dynamic balance task. This supports a potential link between spatial perception and PPPD symptomatology.

The "Census of Four Square Feet"

Science ◽  
1907 ◽  
Vol 26 (676) ◽  
pp. 833-834
Author(s):  
W. L. McAtee
Keyword(s):  
Four Square

Proving Euler’s Four-Square Lemma using Linear Algebra

2018 ◽  
Vol 91 (5) ◽  
pp. 384-385
Author(s):  
Douglass L. Grant
Keyword(s):  
Linear Algebra ◽  
Four Square

Four square loops antenna for circular polarisation and gain enhancement

2010 ◽  
Vol 46 (7) ◽  
pp. 475 ◽  
Author(s):  
Q. Yang ◽  
X. Zhang ◽  
X. Bai ◽  
N. Wang ◽  
Y. Wang ◽  
...  
Keyword(s):  
Circular Polarisation ◽  
Gain Enhancement ◽  
Four Square

scholarly journals FEASIBILITY OF FOUR SQUARE STEP TEST IN HIP FRACTURE PATIENTS

2018 ◽  
Vol 2 (suppl_1) ◽  
pp. 518-518
Author(s):  
H Mutchie ◽  
D Orwig ◽  
B Beamer ◽  
V Conroy ◽  
J Guralnik ◽  
...  
Keyword(s):  
Hip Fracture ◽  
Step Test ◽  
Four Square

The Four Square Laundry: Participant Observation in a War Zone

2001 ◽  
Vol 91 (1/2) ◽  
pp. 414 ◽  
Author(s):  
Lorraine Dowler
Keyword(s):  
Participant Observation ◽  
War Zone ◽  
Four Square

scholarly journals Public Domain in Dispute Settlement of Cancellation of Industrial Design Rights

2020 ◽  
pp. 30-42
Author(s):  
Muchtar Anshary Hamid Labetubun
Keyword(s):  
Dispute Settlement ◽  
Industrial Design ◽  
Public Domain ◽  
Roll Forming ◽  
Economic Rights ◽  
Public Property ◽  
Four Square ◽  
Year 2000

Economic rights in Industrial Design have protection that is limited to a period of 10 years. After the expiration of protection, Industrial Designs that previously owned exclusive rights by the holders of rights to Industrial Design become public property; so that the Industrial Design has no obligation to ask permission to the rights’ holders for Industrial Design to use the Industrial Design. This is generally referred to as Public Domain, as stipulated in Article 2 paragraph (1) and (2) of Law Number 31 Year 2000 concerning Industrial Design, that "Design rights Industry is granted for a new Industrial Design, Industrial Design is considered new if on the date of Acceptance, the Industrial Design is not the same as pre-existing disclosures”. So basically, Industrial Design has a new principle. However, in reality, there are several cases of Industrial Design in resolving disputes over Industrial Design rights that have been registered, because the Industrial Design has become Public Domain, and there has been a cancellation of Industrial Designs including Cases: Industrial Design of Oil Bottles, Industrial Design of Lighters, Industrial Design of Packaging Boxes 4 (Four) Square, Industrial Design CBK 124 Cabinets, Garuda Motorcycles, Industrial Design Disk Places, Industrial Socks Design, Industrial Design Folding Iron Door Chains and Folding Iron Door Leaves, X2 Shoe Strip Industrial Designs, and Industrial Design TMS Roll Forming Machines Machine.

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